I am so glad I found your channel. After watching your video on a circular saw guide track I have been checking out your videos. THIS VIDEO is EXACTLY what I needed to see today. I love how you explain things. It's short, simple and very understandable. Thank you.
Very well explained, i would recommend this to all who are novices in redoing bathroom floors. Its been awhile since i redone a bathroom floor, so i do appreciate the well explained process. Thank you
Thank you so much for this video. I have an issue where my living room, dining room, and kitchen all had luxury vinyl plank flooring installed about five years ago. The installer laid 1/2 inch underlayment over the existing 5/8 inch subfloor. We recently noticed some soft spots in the floor and so I removed a few of the vinyl planks to look under them and found mold and mildew. I went into the crawl space under the house and found that the soft spot areas had mold growing on them. Our home is about 30 inches above the bare ground on stem wall and piers in Florida. I started removing the vinyl planks and found that the underlayment boards were completely rotten and saturated with moisture which was causing the mold and mildew problem. When my son and I began removing the underlayment it just crumbled, and the moisture had caused the subfloor to begin rotting. I cannot identify the type of underlayment but it is not southern yellow pine plywood. There was no felt between the two layers of wood either as I had always found in other houses. I cannot sue the installer because they went out of business during the COVID crisis. At this point my only recourse is to completely remove the subfloor and replace it, but I have the issue of the subfloor being under the walls. Any idea how to get around that problem?
Oh, boy. Well, the good news is that it is repairable, but the bad news is that it will take some effort and cost. The mold-damaged subfloor and underlayment can be removed, and it's possible all of it will need to be taken out. In areas where the wall plate sits on top of the subfloor, the plywood must be carefully cut. You may be able to leave six inches (or whatever) of subfloor around the floor plates if it isn't damaged. Then when new subfloor is installed it will go up to the remaining subfloor and the underlayment will be installed to overlap both. That will add a little strength. The bigger issue is to prevent this from happening again. You obviously have moisture coming up from the ground. There are various methods of sealing the ground and foundation from moisture. I'm not clear on whether you have a completely enclosed crawlspace or not, but either way there are methods to seal it off using thick plastic, sometimes pond liners, or other regionally favored methods. With the subflooring removed it will be easier to do the sealing and I recommend finding a local company with experience in this area. A ventilation system may be required. You may also need a mold remediation company if the problem is really bad. Once you've solved the moisture problem, the mold problem will go away. Probably the vinyl flooring acted as a moisture barrier and kept the moisture contained below the living space, but that also concentrated the moisture in the subfloor. A dew point may have been created there too, depending on your ambient temps. You need local experts to help you sort through this, and I'm sure you aren't the only homeowner to face the problem in your area.
Me and my mom are getting our kitchen done by a cheap quack. He wants to put the cabinets directly on the diagonal, hole ridden, gap filled subfloor. We thought that seemed odd. Because the subfloor is in such bad condition. This has reaffirmed said suspicions, thank you.
The cabinets should be installed over the finished flooring--on top of the tile or wood flooring. While the old cabinets are out and the room is clear the contractor should be checking and repairing the subfloor, installing new underlayment across the whole room, and preparing for the tile or other finish flooring. After the finish flooring is installed, after the walls and ceiling are repaired and painted, and after the rough electric and plumbing have been completed the cabinets can be installed. Then the countertops, the backsplash, the plumbing fixtures and the appliances. You should see this video as well: ruclips.net/video/6nAtSAMDmmc/видео.html
Hello, thanks for your video! I have a situation in which you might shine some light on. I have a 16"OC joist in a house build in the 50s. From the basement, I can see it is a 3/4" T&G plank subfloor. I took a register off the kitchen area (where I plan to work) and measured the subfloor and the underlayment. The underlayment is about 1/4". The current flooring is vinyl with a lot of squeaking sound, I am planning to install porcelain tiles. I was thinking to remove the planks and put 3/4" T&G plywood instead of reinforcing the current subfloor and then top it up with 1/4" cement backboard, but you are calling for a double 3/4" and then cement board. The kitchen connects to a living room and a hallway. I took the laminate flooring transition out, and it is about a 1/2" between the laminate (high side) and the kitchen vinyl (low side). Looking at your transition video, I will put some wood transition. The hallway and the living room will be on the lower side. Right now, the kitchen is 3/4" (plank subfloor) + 1/4" (underlayment) = 1" thickness, give or take. Living room and halfway are 3/4" plank subflooring, probably 1/4" underlayment and laminate =~1 1/2". If I put 3/4"(subfloor)+3/4"(underlayment)+1/4"(cement board)+1/4" (porcelain tiles) = 2" then I hope to have 1/2" difference which I can cover it with a reducer strips/transitions. My question is: do I need to put some subfloor glue between the first 3/4" plywood and the second one? Is there anything else you would suggest based on all the info I have provided above? Thanks in advance :)
Typically in that scenario I will attempt to save the diagonal planks. The work to remove them is long, and you can end up with problems along the wall edges. If the planks are in relatively good shape, without serious warping and without missing pieces, you can use a belt sander to flatten any high spots. Then you can apply 3/4 plywood on top, followed by the 1/4" backerboard. Or, if height with the adjoining rooms will be an issue you can scale back to 5/8 plywood. Use screws to bring the plywood and planks together. The bigger question may be the joist span and size. If the span is great or the size too small, you will get flex in the floor regardless of how much plywood you use. That deflection will crack tiles and loosen grout. There are options, such as installing a new beam midspan or perhaps sistering up new joists with the old. I would take a hard look at the deflection now. One method is to put a laser level in the middle of the floor and watch the dots on the wall as you walk across to see if there is significant deflection.
wow, I was going to place the Hardiebacker over the 1/2" subfloor then tile. but after seeing this, I just might change my mind. project: 1977 track home, 2nd floor demo and retile. thanks for the education.
Tile requires a stiff floor, so the subfloor/underlayment system must be strong enough not to deflect under the weight of people and furnishings. The backerboard is there to provide good adhesion, and it really doesn't offer any structural rigidity. I have seen may expensive tile installations ruined by cracking and delaminated tile because the installer ignored the subfloor/underlayment system and just started laying tile.
By the way, the terms "subfloor" and "underlayment" are often used too loosely or with confused intent. Whatever the term, pay attention to how the different layers work together to form a complete system.
I really thought it's the same thing like some people say "Sheet rock" and some "Dry wall", or is that too - two different things? If I find that type of situation in an old house - the plumer cut the Floor Joist - shouldn't I try to syster a board to it or some other way to make it stronger? From what I saw a few times, those weak joists are the cause for unlevel floor. In my country 90% of the buildings are built from cement blocks and concrete and alot of the wood framed houses are poorly constructed because only the builders who worked in countries like the U.S and Canada really understand Wood construction. There is no real inspection on wood construction cause the inspectors themselves dont really know enpugh. Thank you for your videos! I learnd a lot from you.
Yes, it is a good idea to sister up an additional joist or add other structure when a plumber or another person has compromised the integrity. However, budgets and circumstances may not allow this. In the case of the bathroom in this video, fixing the joist would have meant serious money and tearing apart a relatively new kitchen below.
Great explanation of the different layers of flooring!! We are installing tile in our powder room. Our layers consist(ed) of plywood subfloor, particle board underlayment, and linoleum top layer/flooring. I ripped out the linoleum and scraped out the glue. After a bunch of research, I'm struggling to find direct answers. With particle board being super absorbent, is there anway to seal or add a layer of plywood on top without having to rip out the particle board? The plan is to lay down the Ditra uncoupling membrane as the 2nd underlayment but not sure what to do with that particle board 😩.
I'm going to make this decision easy for you. The particle board must come out. It was a bad idea in the 80s for all floors, and an exceptionally bad idea in bathrooms or other wet areas. It's likely 3/4 inch thick, so set your circular saw for that depth exactly and make a series of cuts in the floor in a checkerboard pattern with each square no bigger than 2x2 feet. Then you can pry up each square. At the edges of the room where the saw can't reach the particle board will break off easily. Clean up all the small remains and leftover nails. Now you can put down a second layer of plywood, which will strengthen the floor system. Try for 3/4 or 5/8 plywood if the height transition to the other room will allow. Use coated deck screws. With the second layer of plywood down, I would recommend you consider using 1/4" hardibacker rather than the Ditra. The Hardibacker is easier to work with and the Ditra really won't buy you much in this scenario.
Thank you!! I really appreciate your help and advice! Our home was built in 2011 but have found quite a few poor choices from this cookie cutter home builder ☹️.
That's astounding that particle board was used in 2011. You do mean particle board and not OSB, which is sometimes called "wafer board"? Particle board looks like sawdust pressed together, which it is. Either one would be a no-go, but particle board is worse. Anyway, it will come up easier than you imagine and your remodel will be better for the decision. You may also find this video helpful: ruclips.net/video/vQKFdO65Qz0/видео.html
Just about to buy our first property. Looking at its pictures online, underneath the vinyl flooring in the bathroom, there appear to be planks of wood, not plywood - is it possible that planks were used as the subfloor once upon a time? Unfortunately, I can see the wood is exposed around the bathtub so I suspect it's potentially rotting because I can see leak marks in the kitchen ceiling downstairs.
Yes, if the planks you see are diagonal in relation to the room, then they could well be the subfloor. Diagonal boards were used as a subfloor in the 20th century up until the 1960s or so when plywood became predominant. If this house was built before 1960 or so that would be a clue. If the boards are not diagonal then you are probably looking at a previous finish floor.
Thank you for sharing this information, actually I'm doing DIY tiles 12x24 in bathroom on wood subfloor. Originally only one 5/8 plywood subfloor with 12" I joist, I forgot to add Any other layer of plywood on top of 5/8 and install Ditra on original 5/8. Now question is do I need to fix it or let it go like that it's small bathroom 28 sqft. Also we have heavy furniture in other rooms no problem sofar so does heavy tile will effect floor ?? Thabks
Well, there are a couple of things to think about. First, you say you have I-joists of some sort, which means the house was built in the modern era. I would be surprised if the original plywood on top of the joists is only 5/8". Are you certain it isn't 3/4", which would be typical? That aside, the problem you may have is flex. You already put the tile down, so presumably you managed to get it flat without "lippage." The Ditra decoupling membrane may help with certain types of movement. What you could find over time is that there is too much flex to the floor up and down, which could result either in cracked tiles or tiles coming loose. This movement will be as a result of people walking on the floor, not the weight of furniture or tile. The small area may work in your favor, but that depends on a number of related factors. So the short answer is that, while I would not have installed tile without the second layer of plywood, you have already done so and already rolled the dice. At this point you might as well see if you get lucky.
Need your advice please. I'm remodeling a small bathroom and installing a tile floor with 12 x 24, 3/8 " thick porcelain tiles. I removed the old tile floor and the mud base down to the subfloor. The subfloor is 1/2 " (nominal) plywood nailed to 2 x 8 joists, 16 " oc. The house was built in the 70s. The flooring adjacent to this room is 3/4 " thick solid oak flooring. (The bathroom subfloor is 3/4" below the hallway oak flooring.) The subfloor is deflecting in one spot in the room when standing on it. My options as I see it are either add a layer of plywood on top of the subfloor or tear out the subfloor and replace with 3/4 " plywood (tongue and groove?), maybe with some blocking. Either way, when estimating the resulting floor thickness, taking into account plywood, thinset layers, cement board and tile, the floor is going to be higher than the adjacent hardwood, thus requiring some type of transition piece. What direction would you suggest?
This is a common issue and one that I often have to explain to homeowners who don't really want to hear it! If you really have 1/2 inch plywood over the joists (are you certain it isn't 5/8?) then that is wholly inadequate. This is especially true with a large tile like 12x24. If you add 3x4 plywood on top, then the backerboard, then the tile, you'll have a step up of a half inch or so. Removing the 1/2 inch ply and replacing it with 3/4 buys you a little as far as deflection, but it also creates a far bigger project and could open up a can of worms. The best compromise I can think of given what you describe is to lay 5/8 plywood over the existing half inch. Use deck screws in a 6-8 inch grid to secure the layers together. Then you could use Schluter Ditra (see my video on that) as the tile base, which will decouple the tile from the plywood and allow a little bit more flex. Finally, I'd encourage you to forget the 12x24 tile and pick a smaller format porcelain tile with a PEI rating of 4 or 5. I have a video on that too! A smaller tile will have more grout lines, which will help absorb more flex without cracking tiles. In the end you'll still have a small step up from the hallway, which you'll need to cover with a custom transition strip OR you can split the step using a marble transition. Sometimes I'll bed the marble on the plywood rather than the tile base in order to split the difference and hide the step.
@@enduringcharm Thanks! Greatly appreciate your guidance and detail. I didn't realize the higher need for a proper subfloor when going with a large format tile such as the 12 x 24 that I chose... Btw, my measurement of the subfloor thickness comes to actual of 15/32 ". I've heard that in our area years ago, 1/2 " plywood was not uncommon for a subfloor.
In my area I see 5/8 ply sometimes in houses built (cheaply) in the 70s. Prior to plywood, diagonal T&G 1x boards were used, typically pine or other softwood. Once in a blue moon I come across 1/2 ply in 16 inch centers, usually in a house that used to be a chicken coop or that sort of thing. It's funny we're having this conversation. Earlier today I was faced with a similar problem on a kitchen remodel. The subfloor is 3x4 plywood over 24 inch center trusses in a townhome. The owner wanted to do a large format tile like you, but after I did the demo I found that the floor was bouncy, deflective, and wavy. Plus, I was also fighting a height problem which would prevent me from strengthening the floor. In light of this, we decided to go with a wood finish floor instead. The wood can flex and move without issue so it made the most sense.
Very well and articulated explanation for us DIY'ers. Quick question. I'm in a similar situation in my kitchen. The dining area is hardwood and the prep area was layers of crap over crap. a five layer nightmare. I need to put a layer of plywood down, then luan, before I do some vinyl so I can raise to meet the dining area. I saw another vid that said to hammer in the luan with 1.5" ring shank underlayment nails every 8" squared. What is the best way to secure the plywood to the subfloor?
I use a coated steel deck screw when installing 1/2, 5/8 or 3/4 plywood. Lauan plywood is typically put down with staples these days, using an air powered gun. Then the staples are covered with a filled before the sheet vinyl is installed.
How are you attaching the 5/8 plywood to the subfloor? Screws going all the way to the joists? I am reading that it should just be attached to the other plywood and not the joists. Help please :)
Anybody who has hard and fast rules in remodeling is going to run into trouble. Your question relates to a number of factors, including the strength of the assembly and the possibility of squeaks. Here are two examples to consider. If the first layer of plywood over the joists is 3/4, in very good condition, and well fastened to the joists then you have a great base from which to work. You can lay down your second layer of plywood and attach it to the first layer of plywood using screws which do not go into the joists. Take care not to use a long screw which might puncture wiring or pipes below, and use a 8-12 inch grid pattern. A different example would be 5/8 plywood on the first layer or maybe even diagonal boards. The wood is in poor condition with soft spots or flaking. It isn't well fastened to the joists. In that case, I'm putting down a second layer of 3/4 ply and I'm screwing into the joists. Then I'll use shorter screws to bring the two layers together in between the joists. So the answer to your question is: it depends. I make an evaluation in each case, aiming for strength stiffness and no squeaks.
Very helpful video! Question: Do you screw cement board straight to underlayment, or do you apply a thin set between underlayment and cement board and then screw down?
While some backerboard manufacturers do recommend using both thinset and screws, I prefer to just use screws. There are two reasons for this. One, the screws used alone will allow some lateral movement and allow the backerboard to decouple from the plywood underneath to a small degree, Two, I want to be kind to the guy who has to tear up the floor the next time. I have tile installations over two decades old with just screws holding down the backerboard.
1/2 inch plywood doesn't have a lot of thickness, and you can easily put the head of a screw right through. In your situation you can use a quality coated deck screw with a bugle head as long as you are careful not to drive the screws like a gorilla. Keep the head just flush with the surface. Use a pattern of every 8-10 inches or so. I generally will use a 1 5/8" length in that situation. However, that leaves the screw tip coming out below. If there are a lot of pipes or electrical wires underneath, you should use a 1 1/4" length instead, and make sure you get a solid "purchase" into the 3/4 plywood with each screw.
I am currently restoring and old 1940's barn and the 2nd floor is all old tongue and groove planks run perpendicular to the joists. Unfortunately they put the joist at 24" OC. My original plan was to put 3/4" t&g subfloor over top and run it parallel this time and framing nail it down thru into the joists. Now im thinking plan B, run the same 3/4" t&g perpendicular to the joists and put a layer of tar paper between to prevent squeeks and screw it down thru into the joists....any thoughts? Thanks in advance
Well, there's a lot to unpack here. First, are the existing t&g boards only 3/4? That could be, since the purpose of the original structure was probably just utility. On the other hand, t&g floor boards were often 5/4 or 6/4. Also, what span are the joists in their unsupported area and what dimensions are the joists? It will make a difference as far as bounce and weight bearing ability. Finally, and importantly, what use are you proposing today? Is it just a storage area? Is it living space? Will you have square dancing competitions up there?
@@enduringcharm Current floor boards are 2 1/2 wide 3/4 thick t&g. It was an old hay loft /chicken coop area. My goal is, I've gutted it out to be one large open area that is now 35'x35'. THe end goal is to just have a rec room area to frequent occasionally. Id like to lay 3/4 t&g plywood over it and just framing nail it down thru the current floor into the joists and put vinyl plank flooring over it. They are 2x10 joists, there is a supporting wall below that that divides off the 1st floor and is off set from the center of the building by 3' to the one side so the one side has a longer span than the other side. They have a lot of wooden X bracing joists on both sides of that wall beneath the floor. On that longer side span there was a corn crib i removed but left the top of that wall where it connected to the floor joists and placed a basement floor jack half along it to help with some bounce on that side
You didn't mention the spacing of the joists, but I'll assume 16 inch centers. So you have 2x10 joists spanning something like 20 feet on the longer side. That is a huge span! The other side at 15 feet is also quite long. Depending on the live load of the floor above, those spans would likely be too great to pass modern muster. I would be inclined to build a supporting wall underneath the long span, at least, which was essentially there before in the form of a corn crib. If a wall would be too invasive as far as the first floor, you could use posts and a beam instead. The advantage of a wall is that you can spread the load and probably not worry about footings. With posts, you create point loads and you may need to install footings. The cross bracing does little as far as span support. We should note, too, that these joists also prevent the exterior walls from spreading. Whether the second floor exterior walls are framed on top of a platform or it is balloon framed, the joists still hold the structure together. You should make sure the joists are well secured to the exterior walls, to each other where they cross the middle beam, and to the middle beam. Once the framing is beefed up, your plan to use 3/4 plywood and a finish floor of vinyl is fine. The vinyl will allow movement, which undoubtedly there will be. If this is a project where you are getting construction permits, the local authority will want to see an architect or engineer sign off on the drawings OR you can do the drawings yourself as long as you support your work with references to the IRC code. There are prescriptive span tables and the like, but for a support wall or support beam with posts, you may need to have a conversation with your code official about the footings. Of course, if you aren't getting permits, then all you need to do is make certain you are doing things right yourself. Either way, if you can find a local structural engineer to swing by and go over your plans with you it would be money well spent. It would be a shame to finish everything off only to determine that the structure needs more support.
Is there a 'debate' on whether to run the underlayment perpendicular (opposite direction) to the existing subfloor or in the same direction but being offset from the existing subfloor? Seems to be. Also seems to be a debate about whether to secure the new underlayment to the floor joists or not. It 'seems' to me though I see lots of thoughts both ways, to go the opposite direction as the subfloor. Any professional thoughts on what you think is the best course, or does it really matter?
First of all, it's important to understand that there is a difference between a remodeling scenario and new construction. Two different animals. In remodeling you typically remove all layers of flooring down to the subfloor and try to keep that layer, although if there is rot present then that layer goes too. Then it's a matter of building back up based on what you have, not what you wish you had. Since tile is the predominate finish flooring in a bathroom or kitchen, I'm interested in creating an installation which will be well adhered and which will not crack. To that end, my main concern is to install the thickest possible underlayment (up to 3/4 plywood), in the largest pieces I can get into the room, and put down so that there are staggered seams in relation to the subfloor. I want flat and strong. The orientation of the underlayment plywood in relation to the subfloor plywood is of lesser concern to me. And, I may go through both layers with screws into the joists if I feel the original subfloor was not well installed, or I may not if the original looks good. In both cases I screw the two layers of plywood together every 8-10 inches, and sometimes closer in areas where I know there will be heavy traffic, such as in front of a toilet or just inside a doorway. In short, I evaluate each project individually rather than go by univeral rules. That's the nature of remodeling versus new construction.
@@enduringcharm Very practical advice. I think you have a very valid point; a lot of advice given is based on new construction principles and ideals. Remodeling often does not allow for such precision and practice. You make the best improvement with the variables surrounding your situation.
I have 1/2 plywood subfloor and was going to add 3/8 plywood to make it level with another room, because the subfloor is 1/2 inch only(old house) should I screw the 3/8 directly into the joists to make it stronger (so many conflicting opinions on this) or should I just screw into the 1/2 inch to avoid movement? Also if I am to screw it into the joists directly, I am confused as where to do it at? Between the 1/2 nail spots and what size screws? appreciate your response!!
The answer about screwing to the joists versus the subfloor plywood is: it depends. When the subfloor is sub-par and I am installing 3/4 plywood over it, I will often screw both to the joists AND to the subfloor. In your case, you intend to install 3/8" plywood over 1/2" plywood. Hopefully you are not trying to tile over that combination, which would not offer enough stiffness. The 3/8 plywood offers almost no structural benefit and if you tried to screw that into the joists you would find that it buckles and bends. You are only installing a spacer with the 3/8" so screwing to the subfloor plywood is fine. You may have trouble doing that, even, since the 1/2" plywood underneath offers little resistance to screw withdrawal. Depending on the finish flooring you are using and the ability to do a transition strip between rooms, you may want to bump up to a thicker plywood.
@@enduringcharm tysm; no title just putting laminate down after pulling up a very thick, heavy, real oak hardwood floors. Would going up to a 1/2 inch on top be any better or would be the same in terms not really adding any added strength? And would nails be a better option than screws into the subfloor ? (Sorry for all the questions, 1st time home buyer doing it myself, I have very little experience here)
Laminate will be fine, that can withstand quite a bit of flex. If you can jump up to 1/2" or 5/8" plywood I would do it. The 3/8" is so thin that the screws could even deflect the plywood or pop right through. You'll have an easier experience if you go 1/2".
Thanks for the explanation. I recently gutted my shower due to a leak and discovered that my subfloor was nothing but a few untreated 2x6 nailed to the joists..
@@enduringcharm they were laid flat. Would you suggest I take them out and lay a plywood subfloor over or simply place a cut out plywood on top of the 2x6?
Well, I look at a remodel as a chance to address all the mistakes of the past. Ideally, you should have both subfloor and underlayment plywood layers under the tub and the entire bath continuous in this manner. So, yes, I would take out the mess that is there, and lay down 3/4 plywood over the joists as a start and then whatever thickness of underlayment you can manage on top of that, given the height of the floor in the adjoining room. I have a video with tricks for that transition. I know it can be tough getting larger sheets of plywood up into a small room, but the larger you can manage, the better. The underlayment should overlap the subfloor seams. After you get the tub or pan installed, the cement backerboard (if you are doing tile) will go up to the edge of the tub or pan.
@@enduringcharm, your assumption was correct. After taking out the shower we decided to do a whole bathroom remodel. Currently tile is installed (poorly from original remodeler). Planning to install lux vinyl
If you will be using an engineered wood or vinyl finish floor you are already in better shape than if you would be using tile. Wood or vinyl will be more forgiving than tile. Putting down 3/4 plywood should be fine, although you may need to use a belt sander or other tool first to take down any high spots on the T&G wood. Try to get that as flat as you can and secured so that there are no squeaks.
Do you ever glue your plywood to the subfloor. I have read several mix reviews on this on many forums. My situation: currently have 1/2" subfloor on upper level and squeaks pretty bad. I had a contractor come out and they recommended glueing 7/16" plywood and then driving screws threw plywood and subfloor to joist to "sandwich" together. What are thoughts on this? Couldn't I just add screws to current 1/2" subfloor to eliminate squek and then screw plywood to subfloor and not worry about screwing to joist?
Squeaks can be be from many different sources--nails sliding against the wood, wood sliding against other wood, etc. Screws do generally hold up better than nails as far as avoiding squeaks. If I understand you correctly you believe you have 1/2 inch plywood as your first layer over the joists? That would be unusual and unfortunate if true. 5/8 inch was used in early days and 3/4 inch is best. Are you certain it isn't 5/8? It's best to identify the source of the squeak first, since it could even be the joist(s) itself. Screwing the first layer (subfloor) down is a start. I generally do not use glue between layers, partially because I want to give the next guy a fighting chance. Gluing the subfloor to the joists is good practice, but it's too late for you on that count. If you get the subfloor squeak free, then screwing the underlayment to that should be enough.
@@enduringcharm The current subfloor is a true 1/2". Joist spacing is 16" and hoist are 2x8 or 2x10, can't measure yet but can see in a crack. I wasn't worried about having to remove glued floor in future because it's for bedrooms and I'm laying laminate down. Could be changed to carpet easily in fututure if someone wanted to. Don't see a reason to ever remove since I'm building up to reinforce original subfloor. I was thinking using 1/4" to build up to meet minimum 3/4" recommended thickness for subfloor. Do you think that should be good and what type of plywood do you recommend, ish, cdx..etc.
Well, it's tough for me to make a judgement without seeing the circumstances, but a 1/2 inch subfloor is doing almost nothing for you. It will flex and allow the joists to flex too, which may be once source of your squeaks. If you have the height available in the floor of the adjoining hallway or room I would install 3/4 plywood over what is there. I'd screw down the 3/4 after screwing down the existing 1/2 inch. I'd still skip the adhesive, which is likely to cause gaps between the layers and contribute to future squeaks when the gaps eventually sag and touch.
Corey-- there isn't a simple answer. Whether you screw through the subfloor into the joists or not can depend on the details of the situation. Just today I installed 3/4 plywood over old diagonal boards and chose to use long screws into the joists and shorter screws into the boards. Otherwise, the diagonal boards would provide little support. In your situation I would typically not screw into the joists, but use a fairly tight pattern of screws into the first layer. However, if I found that the first layer had been hacked up into small sections, or looked otherwise damaged, I might choose to go in to the joints as well.
Hi Preparing uneven subfloor for tile by adding another layer of plywood and then Detra but the floor is not level should i first use self leveler and then the plywood or installing the second layer of ply wood and then self leveler before installing Ditra and tile ? also My house is build in 1994 if i use the thick ply wood u use the floor get to high compare the the rest of the house and it would not be easy to find a translation i intend to use one Cm underlayment and then Ditra and then the granite slab {natural stone } any suggestion thanks
Level and flat are two different things. Level is important for placement of a tub or shower pan, but it's not that important for tile. Flat is very important for tile, though. You don't mention how far out of level or flat your floor might be. To need a self leveling compound the problem is generally pretty bad. The self-leveler goes down before a second layer of plywood. I'm confused about your mention of a "one Cm" underlayment. Do you mean a one centimeter thick plywood? The closest I know of to that would be 3/8 inch (actual 11/32). Such a thin plywood would add no strength to speak of, all it might do is offer a smoother surface and additional height. Generally 5/8" plywood is the thinnest I'll go for the underlayment, although once or twice I was forced to use 1/2". If getting the floor flat is your only concern, you may be able to make up some waviness with the thinset under the Ditra. But, I'd need more information to offer specific advice.
@@enduringcharm hi thanks for reply so the floor is not flat when i use leveler i see it is like a roller coaster the plywood i meant 1/2 inch by adding that new plywood the thickness of my floor get to 1.19 inch and i am trying to install natural stone so do u think is that good enough for stone ? and the other thing if i install the new plywood and than i use self leveler compound does it matter ? the reason i am asking i want to glue and screw the new plywood to sub floor if i use self leveler first than i wont be able to use carpenter glue also the screw would not crack the sell leveler if i install the plywood after ??thanks
Okay, so flatness is your concern. What does "roller coaster" mean, are the dips more than an 1/8 inch? Are the joists on 16 inch centers? Is the subfloor, the first layer of plywood, 3/4 inch? If not then it may be better to replace that than to try and make it flat. Gluing the underlayment to the subfloor really won't buy you anything. You need strong material to span the joists and not deflect with the weight of the tile. If there is one area that dips due to the joists you could certainly use self-leveling material to flatten out that dip. But, it will add no strength. For a heavy tile you need strength and stiffness. Also, for larger tiles over 12 inches in one dimension the flatness of the floor becomes more important.
Self leveling compound should be used when you have a severe falloff in an area, perhaps a corner that drops off by a half inch or three quarters of an inch in a tub area. I would be very surprised indeed if you have 3/4 inch plywood sagging in-between 16 inch centers. My guess is that you may be seeing high spots at plywood seams where a joist or beam is higher than neighbor joists. If you are using a large format tile they can rock on top of high spots like that. Sometimes a belt sander can be used to knock off the high spots like that. If the whole floor is relatively flat but you are just seeing high spots or a few areas of minor sag, then I would knock off the high spots and then put down 5/8 or 3/4 plywood as underlayment. If you have a height issue with the adjoining room you can install a tapered marble transition on top of the underlayment, then install the ditra and tile up to the transition. You might also consider skipping the Ditra and using 1/4 inch hardibacker. Screw the second layer of plywood to the subfloor every 6-8 inches and check for squeaks before you go further.
I have a 3/4” diagonal plank subfloor on 16” joists in my bathroom. My hallway floor is 3/4” hardwood, I really don’t want to use 3/4” plywood with 1/4” hardie due to the height of the threshold. Think I could skate by on 1/2” plywood with 1/4” hardie? That would make 1-1/4” base for the 12x24” ceramic tiles. Please help 🤣
While the condition of the diagonal boards and the span of the joists are part of the equation, I can tell you are already asking for trouble. A 12x24 tile, which is popular these days, is a large format tile which demands a flat substrate with little flex. If the substrate is not flat you'll end up with lippage, where one tile edge is slightly above another. If you don't eliminate flex you'll get cracked grout lines or even cracked tiles. With a large tile there isn't a lot of grout line opportunity to hide a wavy floor, either. 1/2 inch plywood provides almost no help as far as flex because it has little rigidity. You'd be relying on the diagonal boards for rigidity and the 1/2 inch plywood would potentially smooth over some board gaps. That's not much foundation for new tile. I'd prefer to see at least 5/8 plywood, generously screwed, then either the 1/4 inch hardibacker or potentially Schulter Ditra. Another option is to remove the diagonal boards and replace with 3/4 inch plywood, followed by 5/8 ply. Also, if you can use porcelain tile instead of ceramic, you'll have a better chance. There are tricks to ease the transition so the height issue isn't as bad. See my video here: ruclips.net/video/vQKFdO65Qz0/видео.html
@@enduringcharm Thank you sir, greatly appreciate your help and time! I’ve actually got some 19/32 plywood I originally bought for the job, was going to take back this morning and get 1/2”... glad I opened RUclips first 🤣 So the 5/8” plywood + 1/4” hardie and I should be fine? I really don’t wanna rip the subfloor out 😩, hell I may just put down 3/4” ply and some damn laminate or something so I don’t have to worry about it 🤣... thanks again for sharing some knowledge. The video you sent me was very helpful as well, I’m going to watch a few more now lol... def earned my sub brother!
Without being there I can't give a firm answer, but if the diagonal boards are in good shape (not cupped or cracked), and the joist span isn't a great amount, you'll probably be okay. Screw down the diagonal boards first and use a belt sander to take down any high spots. Install the 5/8 plywood with high quality deck screws every 8-10 inches. Check that for flatness and excessive bounce. Then install the hardibacker, possibly using the transition trick I showed in that other video.
I love is video, awesome. Hi, I’m want to install Carrara Marble 12 in. x 24 in. Peel and Stick Vinyl Tile to my bathroom. At the moment I only have subfloor. I’m sure I need something between my subfloor and vinyl tile I just don’t know what, please help me
Peel and stick is not something I use very often. It's a budget choice and shouldn't be expected to last very long, especially in a bath. To install it, you'll need a very flat and smooth underlayment. Lauan plywood is often used, although you might look for specialty versions of this plywood sure as SurePly, which are specifically designed for the purpose. The 1/4 inch sheets are put down with stainless steel staples and the the seams are filled so they don't telegraph through the tile. You can tile right over this, but I would suggest priming the entire surface first and letting that primer cure for several days before applying the tile.
Thanks so much for this video! I've learned more from your video and your reply comments than I have elsewhere while researching! I am redoing a small bathroom (35 sq ft) in our 60s rancher. The 5/8" underlayment has some water damage so I am replacing that and hopefully leaving the 1/2" subfloor beneath (plywood maybe). It looks to be in good condition when I look up at it in the crawl space. My question is.. will 1/4" Durock backerboard suffice for tiling if I have the 1/2" sub + 23/32" underlayment (about 1.2" total) ? I plan on doing a layer of thinset under backerboard as well. The tiles are hexagon shape approx. 8x8". Thank you!!
There's another factor to think about, which is the joists. If your floor joists are long, or not very wide, you can get more flex and movement than if you have shorter lengths and wider boards. Tile and flex don't go together very well. You have to make a judgement call, but if you feel a lot of bounce in the floor when you walk, you may have issues. Fortunately you are using a smaller tile, which will fare better with movement because of the additional grout lines. Anyway, my advice is to use the thickest plywood underlayment you can manage given the height of the floor in relation to the adjacent hallway. Sometimes you can cheat a little by ending the backerboard at the edge of the door threshold and installing your marble transition on the plywood rather than the backerboard. That buys you another 1/4 inch and if you get the right thickness of marble it will be level with the tile. I'm not a fan of Durock at all. It has no stiffness or structural rigidity to it. I'd highly encourage you to use Hardibacker instead, and just use screws--no thinset beneath. This will allow a little bit of decoupling movement. Or, if you really fear that movement will be an issue, you could use Schluter Ditra instead.
@@enduringcharm Thanks so much for your reply and all this helpful info. I think I might actually use Schluter Ditra based on your recommendation and after looking into a little more. If I use backer board instead I'll definitely use Hardie. Thanks again! I am subscribing to your channel
If you're remodeling and find a subfloor already have an underlayment on top, would you add another layer to it or replace the entire underlayment to improve the strength of the floor?
You've touched on a pet peeve of mine! People do put new layers on top of the old, including layers on top of finished flooring. Professionals do not! The only time I would leave the underlayment alone is when it is perfect shape due to the type of finish flooring originally installed. For example, if you had linoleum or vinyl sheet flooring that was installed on top of 1/4" luan plywood. Sometimes you can take up the sheet flooring and the luan plywood and discover that you have perfectly preserved 3/4 or 5/8 underlayment on top of the 3/4 subfloor. In that case you could add 1/4 cement backerboard and then tile, to give a common example. For most instances, though, you will find a beat up plywood underlayment that had tile over it, or something like that, and you should remove all the layers down to the original subfloor and build back up. Often the original layers were nailed, not screwed, which is also not ideal. In my work I always take up the old layers down to a clean starting point and build back up, and I use screws to avoid squeaks.
+enduringcharm Thanks! That answered my question. My underlayment has cracks and thinset marks all over it. I guess I won't be reusing that. If I put down plywood underlayment, can it be thicker than the actual subfloor?
As a general rule, thicker is better. Ideally you'll have two solid layers of 3/4 plywood and then you can put down your finish floor system, which may include cement backerboard and tile, or wood, or whatever. However, you have to watch the adjoining room. Measure from that room's finish floor to determine how much height you have--you want to have the two finish floors match up or come close to it. With that measurement you can determine how thick you can go with your underlayment.
@@enduringcharm how much thicker can you go with your floor compared to the adjoining room and it be reasonable. I have a problem where the finished floor in my bedrooms are the original tongue and groove three-quarter inch plank flooring, and my entire bathroom flooring rotted out. I replaced with three quarter inch pressure treated pine in the bathroom for stability and this made the joining bedroom level. The problem is I'm wanting to add tile and from everything I've seen and researched the best idea is to add half inch plywood underlayment and then a quarter inch Hardy backer before I tile. I'm thinking this is going to make the bathroom floor way larger than the adjoining room. What solution should I use? Thank you for your help!
If you are installing tile, then getting these details right is critical. if you are installing something flexible like wood flooring or laminate flooring it may be less critical. I'm guessing you need to see this video too: ruclips.net/video/vQKFdO65Qz0/видео.htmlsi=_PZXo579ziQhMjKl
Do you have any videos on how to level underlayment on an existing subfloor. Working on a house built about 1920 and the subfloor is diagonal shiplap and its very uneven. Also wondering what type of plywood to put on top of the subfloor.
Diagonal boards can be a real challenge. The boards themselves can become cupped or twisted and the edges where they line up with the next board often create a lip. One solution is to pull it all up and start over with plywood and I've had occasion to have to do that. Short of that, you can work the surface foot by foot to level and flatten it. remove protruding nails, and use a belt sander and/or planer to bring the boards closer to flat. Self leveling cement is generally not a good option for diagonal boards because it will crack with the movement of the individual boards. When you've done the best you can, install a layer of 3/4 plywood using screws, or the thickest plywood you can manage.
enduringcharm I don’t think you understand how amazing the timing of your comment is. I am dealing with this exact situation with 1 x 5 boards for a subfloor. Old house so the boards are curled up or down with some water exposure. Pulling them up isn’t an option so been trying to figure out what to do to get level them out for tile.
enduringcharm do you think it’s ok to use staples to connect the plywood underlayment to the subfloor or are screws necessary? I’ve heard there are screws with tips that cross to give extra grip. Also would you put some material in the joints between the boards? Someone suggested liquid nails. I thought kitchen and bath caulking to inhibit mold growth.
Screws are preferable, especially in this situation. The diagonal boards will want to move with the seasons, and staples will eventually work loose. Screws simply have better holding power. A high quality deck screw will work fine. As for caulking between the diagonal boards--not necessary and not helpful. The wood will continue to expand and contract and the caulking will do nothing. What you may want to do is sandwich a layer of rosin paper or tar paper (30# felt) between the diagonal boards and the new plywood. It may help prevent squeaking between the two layers and also keep them separate as far as any future moisture.
This could be clarified. Some manufacturers do specify that the backerboard be adhered to the underlayment using thinset mortar. In that case you are right--there isn't much decoupling taking place. However, I just use screws to attach the backerboard to the underlayment. In that instance, there is some decoupling because the movement of the underlayment can be absorbed by the play in the screw connections. I mean, it's not a floating floor, but some movement is absorbed by the assembly. I have seen many tiled floors without this method and there are cracked tiles right down the line of the plywood underneath.
I am so glad I found your channel. After watching your video on a circular saw guide track I have been checking out your videos. THIS VIDEO is EXACTLY what I needed to see today. I love how you explain things. It's short, simple and very understandable. Thank you.
Very well explained, i would recommend this to all who are novices in redoing bathroom floors. Its been awhile since i redone a bathroom floor, so i do appreciate the well explained process. Thank you
Thank you so much for this video. I have an issue where my living room, dining room, and kitchen all had luxury vinyl plank flooring installed about five years ago. The installer laid 1/2 inch underlayment over the existing 5/8 inch subfloor. We recently noticed some soft spots in the floor and so I removed a few of the vinyl planks to look under them and found mold and mildew. I went into the crawl space under the house and found that the soft spot areas had mold growing on them. Our home is about 30 inches above the bare ground on stem wall and piers in Florida. I started removing the vinyl planks and found that the underlayment boards were completely rotten and saturated with moisture which was causing the mold and mildew problem. When my son and I began removing the underlayment it just crumbled, and the moisture had caused the subfloor to begin rotting. I cannot identify the type of underlayment but it is not southern yellow pine plywood. There was no felt between the two layers of wood either as I had always found in other houses. I cannot sue the installer because they went out of business during the COVID crisis. At this point my only recourse is to completely remove the subfloor and replace it, but I have the issue of the subfloor being under the walls. Any idea how to get around that problem?
Oh, boy. Well, the good news is that it is repairable, but the bad news is that it will take some effort and cost. The mold-damaged subfloor and underlayment can be removed, and it's possible all of it will need to be taken out. In areas where the wall plate sits on top of the subfloor, the plywood must be carefully cut. You may be able to leave six inches (or whatever) of subfloor around the floor plates if it isn't damaged. Then when new subfloor is installed it will go up to the remaining subfloor and the underlayment will be installed to overlap both. That will add a little strength.
The bigger issue is to prevent this from happening again. You obviously have moisture coming up from the ground. There are various methods of sealing the ground and foundation from moisture. I'm not clear on whether you have a completely enclosed crawlspace or not, but either way there are methods to seal it off using thick plastic, sometimes pond liners, or other regionally favored methods. With the subflooring removed it will be easier to do the sealing and I recommend finding a local company with experience in this area. A ventilation system may be required. You may also need a mold remediation company if the problem is really bad. Once you've solved the moisture problem, the mold problem will go away. Probably the vinyl flooring acted as a moisture barrier and kept the moisture contained below the living space, but that also concentrated the moisture in the subfloor. A dew point may have been created there too, depending on your ambient temps. You need local experts to help you sort through this, and I'm sure you aren't the only homeowner to face the problem in your area.
Thanks for your quick and concise video. It has helped me make decisions on my bathroom remodel.
This is the video I was looking for, Thank you!! I learned a lot.
Thank you . This was helpful in my decision to lay 1/4 inch. Good explanation.
Thank you for explaining it in details, very informational and to the point I must say.
Me and my mom are getting our kitchen done by a cheap quack. He wants to put the cabinets directly on the diagonal, hole ridden, gap filled subfloor. We thought that seemed odd. Because the subfloor is in such bad condition. This has reaffirmed said suspicions, thank you.
The cabinets should be installed over the finished flooring--on top of the tile or wood flooring. While the old cabinets are out and the room is clear the contractor should be checking and repairing the subfloor, installing new underlayment across the whole room, and preparing for the tile or other finish flooring. After the finish flooring is installed, after the walls and ceiling are repaired and painted, and after the rough electric and plumbing have been completed the cabinets can be installed. Then the countertops, the backsplash, the plumbing fixtures and the appliances. You should see this video as well:
ruclips.net/video/6nAtSAMDmmc/видео.html
Hello, thanks for your video!
I have a situation in which you might shine some light on. I have a 16"OC joist in a house build in the 50s. From the basement, I can see it is a 3/4" T&G plank subfloor. I took a register off the kitchen area (where I plan to work) and measured the subfloor and the underlayment. The underlayment is about 1/4". The current flooring is vinyl with a lot of squeaking sound, I am planning to install porcelain tiles. I was thinking to remove the planks and put 3/4" T&G plywood instead of reinforcing the current subfloor and then top it up with 1/4" cement backboard, but you are calling for a double 3/4" and then cement board.
The kitchen connects to a living room and a hallway. I took the laminate flooring transition out, and it is about a 1/2" between the laminate (high side) and the kitchen vinyl (low side). Looking at your transition video, I will put some wood transition. The hallway and the living room will be on the lower side. Right now, the kitchen is 3/4" (plank subfloor) + 1/4" (underlayment) = 1" thickness, give or take. Living room and halfway are 3/4" plank subflooring, probably 1/4" underlayment and laminate =~1 1/2". If I put 3/4"(subfloor)+3/4"(underlayment)+1/4"(cement board)+1/4" (porcelain tiles) = 2" then I hope to have 1/2" difference which I can cover it with a reducer strips/transitions.
My question is: do I need to put some subfloor glue between the first 3/4" plywood and the second one?
Is there anything else you would suggest based on all the info I have provided above?
Thanks in advance :)
Typically in that scenario I will attempt to save the diagonal planks. The work to remove them is long, and you can end up with problems along the wall edges. If the planks are in relatively good shape, without serious warping and without missing pieces, you can use a belt sander to flatten any high spots. Then you can apply 3/4 plywood on top, followed by the 1/4" backerboard. Or, if height with the adjoining rooms will be an issue you can scale back to 5/8 plywood. Use screws to bring the plywood and planks together.
The bigger question may be the joist span and size. If the span is great or the size too small, you will get flex in the floor regardless of how much plywood you use. That deflection will crack tiles and loosen grout. There are options, such as installing a new beam midspan or perhaps sistering up new joists with the old. I would take a hard look at the deflection now. One method is to put a laser level in the middle of the floor and watch the dots on the wall as you walk across to see if there is significant deflection.
3/4" is best over a 1/2" structural subfloor...but 5/8" is good depending on the number of plys in the sheets. Good information.
wow, I was going to place the Hardiebacker over the 1/2" subfloor then tile. but after seeing this, I just might change my mind.
project: 1977 track home, 2nd floor demo and retile.
thanks for the education.
Tile requires a stiff floor, so the subfloor/underlayment system must be strong enough not to deflect under the weight of people and furnishings. The backerboard is there to provide good adhesion, and it really doesn't offer any structural rigidity. I have seen may expensive tile installations ruined by cracking and delaminated tile because the installer ignored the subfloor/underlayment system and just started laying tile.
By the way, the terms "subfloor" and "underlayment" are often used too loosely or with confused intent. Whatever the term, pay attention to how the different layers work together to form a complete system.
I really thought it's the same thing like some people say "Sheet rock" and some "Dry wall", or is that too - two different things?
If I find that type of situation in an old house - the plumer cut the Floor Joist - shouldn't I try to syster a board to it or some other way to make it stronger?
From what I saw a few times, those weak joists are the cause for unlevel floor.
In my country 90% of the buildings are built from cement blocks and concrete and alot of the wood framed houses are poorly constructed because only the builders who worked in countries like the U.S and Canada really understand Wood construction.
There is no real inspection on wood construction cause the inspectors themselves dont really know enpugh.
Thank you for your videos!
I learnd a lot from you.
Yes, it is a good idea to sister up an additional joist or add other structure when a plumber or another person has compromised the integrity. However, budgets and circumstances may not allow this. In the case of the bathroom in this video, fixing the joist would have meant serious money and tearing apart a relatively new kitchen below.
Great explanation of the different layers of flooring!! We are installing tile in our powder room. Our layers consist(ed) of plywood subfloor, particle board underlayment, and linoleum top layer/flooring. I ripped out the linoleum and scraped out the glue. After a bunch of research, I'm struggling to find direct answers. With particle board being super absorbent, is there anway to seal or add a layer of plywood on top without having to rip out the particle board? The plan is to lay down the Ditra uncoupling membrane as the 2nd underlayment but not sure what to do with that particle board 😩.
I'm going to make this decision easy for you. The particle board must come out. It was a bad idea in the 80s for all floors, and an exceptionally bad idea in bathrooms or other wet areas. It's likely 3/4 inch thick, so set your circular saw for that depth exactly and make a series of cuts in the floor in a checkerboard pattern with each square no bigger than 2x2 feet. Then you can pry up each square. At the edges of the room where the saw can't reach the particle board will break off easily.
Clean up all the small remains and leftover nails. Now you can put down a second layer of plywood, which will strengthen the floor system. Try for 3/4 or 5/8 plywood if the height transition to the other room will allow. Use coated deck screws. With the second layer of plywood down, I would recommend you consider using 1/4" hardibacker rather than the Ditra. The Hardibacker is easier to work with and the Ditra really won't buy you much in this scenario.
Thank you!! I really appreciate your help and advice! Our home was built in 2011 but have found quite a few poor choices from this cookie cutter home builder ☹️.
That's astounding that particle board was used in 2011. You do mean particle board and not OSB, which is sometimes called "wafer board"? Particle board looks like sawdust pressed together, which it is. Either one would be a no-go, but particle board is worse. Anyway, it will come up easier than you imagine and your remodel will be better for the decision. You may also find this video helpful: ruclips.net/video/vQKFdO65Qz0/видео.html
Just about to buy our first property. Looking at its pictures online, underneath the vinyl flooring in the bathroom, there appear to be planks of wood, not plywood - is it possible that planks were used as the subfloor once upon a time? Unfortunately, I can see the wood is exposed around the bathtub so I suspect it's potentially rotting because I can see leak marks in the kitchen ceiling downstairs.
Yes, if the planks you see are diagonal in relation to the room, then they could well be the subfloor. Diagonal boards were used as a subfloor in the 20th century up until the 1960s or so when plywood became predominant. If this house was built before 1960 or so that would be a clue. If the boards are not diagonal then you are probably looking at a previous finish floor.
Thank you for sharing this information, actually I'm doing DIY tiles 12x24 in bathroom on wood subfloor.
Originally only one 5/8 plywood subfloor with 12" I joist, I forgot to add Any other layer of plywood on top of 5/8 and install Ditra on original 5/8. Now question is do I need to fix it or let it go like that it's small bathroom 28 sqft.
Also we have heavy furniture in other rooms no problem sofar so does heavy tile will effect floor ??
Thabks
Well, there are a couple of things to think about. First, you say you have I-joists of some sort, which means the house was built in the modern era. I would be surprised if the original plywood on top of the joists is only 5/8". Are you certain it isn't 3/4", which would be typical?
That aside, the problem you may have is flex. You already put the tile down, so presumably you managed to get it flat without "lippage." The Ditra decoupling membrane may help with certain types of movement. What you could find over time is that there is too much flex to the floor up and down, which could result either in cracked tiles or tiles coming loose. This movement will be as a result of people walking on the floor, not the weight of furniture or tile. The small area may work in your favor, but that depends on a number of related factors. So the short answer is that, while I would not have installed tile without the second layer of plywood, you have already done so and already rolled the dice. At this point you might as well see if you get lucky.
Need your advice please. I'm remodeling a small bathroom and installing a tile floor with 12 x 24, 3/8 " thick porcelain tiles. I removed the old tile floor and the mud base down to the subfloor. The subfloor is 1/2 " (nominal) plywood nailed to 2 x 8 joists, 16 " oc. The house was built in the 70s. The flooring adjacent to this room is 3/4 " thick solid oak flooring. (The bathroom subfloor is 3/4" below the hallway oak flooring.) The subfloor is deflecting in one spot in the room when standing on it. My options as I see it are either add a layer of plywood on top of the subfloor or tear out the subfloor and replace with 3/4 " plywood (tongue and groove?), maybe with some blocking. Either way, when estimating the resulting floor thickness, taking into account plywood, thinset layers, cement board and tile, the floor is going to be higher than the adjacent hardwood, thus requiring some type of transition piece.
What direction would you suggest?
This is a common issue and one that I often have to explain to homeowners who don't really want to hear it! If you really have 1/2 inch plywood over the joists (are you certain it isn't 5/8?) then that is wholly inadequate. This is especially true with a large tile like 12x24. If you add 3x4 plywood on top, then the backerboard, then the tile, you'll have a step up of a half inch or so. Removing the 1/2 inch ply and replacing it with 3/4 buys you a little as far as deflection, but it also creates a far bigger project and could open up a can of worms. The best compromise I can think of given what you describe is to lay 5/8 plywood over the existing half inch. Use deck screws in a 6-8 inch grid to secure the layers together. Then you could use Schluter Ditra (see my video on that) as the tile base, which will decouple the tile from the plywood and allow a little bit more flex. Finally, I'd encourage you to forget the 12x24 tile and pick a smaller format porcelain tile with a PEI rating of 4 or 5. I have a video on that too! A smaller tile will have more grout lines, which will help absorb more flex without cracking tiles. In the end you'll still have a small step up from the hallway, which you'll need to cover with a custom transition strip OR you can split the step using a marble transition. Sometimes I'll bed the marble on the plywood rather than the tile base in order to split the difference and hide the step.
@@enduringcharm Thanks! Greatly appreciate your guidance and detail. I didn't realize the higher need for a proper subfloor when going with a large format tile such as the 12 x 24 that I chose... Btw, my measurement of the subfloor thickness comes to actual of 15/32 ". I've heard that in our area years ago, 1/2 " plywood was not uncommon for a subfloor.
In my area I see 5/8 ply sometimes in houses built (cheaply) in the 70s. Prior to plywood, diagonal T&G 1x boards were used, typically pine or other softwood. Once in a blue moon I come across 1/2 ply in 16 inch centers, usually in a house that used to be a chicken coop or that sort of thing. It's funny we're having this conversation. Earlier today I was faced with a similar problem on a kitchen remodel. The subfloor is 3x4 plywood over 24 inch center trusses in a townhome. The owner wanted to do a large format tile like you, but after I did the demo I found that the floor was bouncy, deflective, and wavy. Plus, I was also fighting a height problem which would prevent me from strengthening the floor. In light of this, we decided to go with a wood finish floor instead. The wood can flex and move without issue so it made the most sense.
Very well and articulated explanation for us DIY'ers. Quick question. I'm in a similar situation in my kitchen. The dining area is hardwood and the prep area was layers of crap over crap. a five layer nightmare. I need to put a layer of plywood down, then luan, before I do some vinyl so I can raise to meet the dining area. I saw another vid that said to hammer in the luan with 1.5" ring shank underlayment nails every 8" squared. What is the best way to secure the plywood to the subfloor?
I use a coated steel deck screw when installing 1/2, 5/8 or 3/4 plywood. Lauan plywood is typically put down with staples these days, using an air powered gun. Then the staples are covered with a filled before the sheet vinyl is installed.
How are you attaching the 5/8 plywood to the subfloor? Screws going all the way to the joists? I am reading that it should just be attached to the other plywood and not the joists. Help please :)
Anybody who has hard and fast rules in remodeling is going to run into trouble. Your question relates to a number of factors, including the strength of the assembly and the possibility of squeaks. Here are two examples to consider. If the first layer of plywood over the joists is 3/4, in very good condition, and well fastened to the joists then you have a great base from which to work. You can lay down your second layer of plywood and attach it to the first layer of plywood using screws which do not go into the joists. Take care not to use a long screw which might puncture wiring or pipes below, and use a 8-12 inch grid pattern. A different example would be 5/8 plywood on the first layer or maybe even diagonal boards. The wood is in poor condition with soft spots or flaking. It isn't well fastened to the joists. In that case, I'm putting down a second layer of 3/4 ply and I'm screwing into the joists. Then I'll use shorter screws to bring the two layers together in between the joists. So the answer to your question is: it depends. I make an evaluation in each case, aiming for strength stiffness and no squeaks.
@@enduringcharmThank you!
Very informative! Thank you
Very helpful video! Question: Do you screw cement board straight to underlayment, or do you apply a thin set between underlayment and cement board and then screw down?
While some backerboard manufacturers do recommend using both thinset and screws, I prefer to just use screws. There are two reasons for this. One, the screws used alone will allow some lateral movement and allow the backerboard to decouple from the plywood underneath to a small degree, Two, I want to be kind to the guy who has to tear up the floor the next time. I have tile installations over two decades old with just screws holding down the backerboard.
I have a question: to secure1/2" plywood to the 3/4" subfloor. What # of screw to use and how long should they be?
1/2 inch plywood doesn't have a lot of thickness, and you can easily put the head of a screw right through. In your situation you can use a quality coated deck screw with a bugle head as long as you are careful not to drive the screws like a gorilla. Keep the head just flush with the surface. Use a pattern of every 8-10 inches or so. I generally will use a 1 5/8" length in that situation. However, that leaves the screw tip coming out below. If there are a lot of pipes or electrical wires underneath, you should use a 1 1/4" length instead, and make sure you get a solid "purchase" into the 3/4 plywood with each screw.
I am currently restoring and old 1940's barn and the 2nd floor is all old tongue and groove planks run perpendicular to the joists. Unfortunately they put the joist at 24" OC. My original plan was to put 3/4" t&g subfloor over top and run it parallel this time and framing nail it down thru into the joists.
Now im thinking plan B, run the same 3/4" t&g perpendicular to the joists and put a layer of tar paper between to prevent squeeks and screw it down thru into the joists....any thoughts? Thanks in advance
Well, there's a lot to unpack here. First, are the existing t&g boards only 3/4? That could be, since the purpose of the original structure was probably just utility. On the other hand, t&g floor boards were often 5/4 or 6/4. Also, what span are the joists in their unsupported area and what dimensions are the joists? It will make a difference as far as bounce and weight bearing ability. Finally, and importantly, what use are you proposing today? Is it just a storage area? Is it living space? Will you have square dancing competitions up there?
@@enduringcharm
Current floor boards are 2 1/2 wide 3/4 thick t&g. It was an old hay loft /chicken coop area. My goal is, I've gutted it out to be one large open area that is now 35'x35'. THe end goal is to just have a rec room area to frequent occasionally. Id like to lay 3/4 t&g plywood over it and just framing nail it down thru the current floor into the joists and put vinyl plank flooring over it.
They are 2x10 joists, there is a supporting wall below that that divides off the 1st floor and is off set from the center of the building by 3' to the one side so the one side has a longer span than the other side. They have a lot of wooden X bracing joists on both sides of that wall beneath the floor. On that longer side span there was a corn crib i removed but left the top of that wall where it connected to the floor joists and placed a basement floor jack half along it to help with some bounce on that side
You didn't mention the spacing of the joists, but I'll assume 16 inch centers. So you have 2x10 joists spanning something like 20 feet on the longer side. That is a huge span! The other side at 15 feet is also quite long. Depending on the live load of the floor above, those spans would likely be too great to pass modern muster. I would be inclined to build a supporting wall underneath the long span, at least, which was essentially there before in the form of a corn crib. If a wall would be too invasive as far as the first floor, you could use posts and a beam instead. The advantage of a wall is that you can spread the load and probably not worry about footings. With posts, you create point loads and you may need to install footings. The cross bracing does little as far as span support.
We should note, too, that these joists also prevent the exterior walls from spreading. Whether the second floor exterior walls are framed on top of a platform or it is balloon framed, the joists still hold the structure together. You should make sure the joists are well secured to the exterior walls, to each other where they cross the middle beam, and to the middle beam.
Once the framing is beefed up, your plan to use 3/4 plywood and a finish floor of vinyl is fine. The vinyl will allow movement, which undoubtedly there will be. If this is a project where you are getting construction permits, the local authority will want to see an architect or engineer sign off on the drawings OR you can do the drawings yourself as long as you support your work with references to the IRC code. There are prescriptive span tables and the like, but for a support wall or support beam with posts, you may need to have a conversation with your code official about the footings. Of course, if you aren't getting permits, then all you need to do is make certain you are doing things right yourself. Either way, if you can find a local structural engineer to swing by and go over your plans with you it would be money well spent. It would be a shame to finish everything off only to determine that the structure needs more support.
Is there a 'debate' on whether to run the underlayment perpendicular (opposite direction) to the existing subfloor or in the same direction but being offset from the existing subfloor? Seems to be. Also seems to be a debate about whether to secure the new underlayment to the floor joists or not. It 'seems' to me though I see lots of thoughts both ways, to go the opposite direction as the subfloor. Any professional thoughts on what you think is the best course, or does it really matter?
First of all, it's important to understand that there is a difference between a remodeling scenario and new construction. Two different animals. In remodeling you typically remove all layers of flooring down to the subfloor and try to keep that layer, although if there is rot present then that layer goes too. Then it's a matter of building back up based on what you have, not what you wish you had. Since tile is the predominate finish flooring in a bathroom or kitchen, I'm interested in creating an installation which will be well adhered and which will not crack. To that end, my main concern is to install the thickest possible underlayment (up to 3/4 plywood), in the largest pieces I can get into the room, and put down so that there are staggered seams in relation to the subfloor. I want flat and strong.
The orientation of the underlayment plywood in relation to the subfloor plywood is of lesser concern to me. And, I may go through both layers with screws into the joists if I feel the original subfloor was not well installed, or I may not if the original looks good. In both cases I screw the two layers of plywood together every 8-10 inches, and sometimes closer in areas where I know there will be heavy traffic, such as in front of a toilet or just inside a doorway. In short, I evaluate each project individually rather than go by univeral rules. That's the nature of remodeling versus new construction.
@@enduringcharm Very practical advice. I think you have a very valid point; a lot of advice given is based on new construction principles and ideals. Remodeling often does not allow for such precision and practice. You make the best improvement with the variables surrounding your situation.
I have 1/2 plywood subfloor and was going to add 3/8 plywood to make it level with another room, because the subfloor is 1/2 inch only(old house) should I screw the 3/8 directly into the joists to make it stronger (so many conflicting opinions on this) or should I just screw into the 1/2 inch to avoid movement? Also if I am to screw it into the joists directly, I am confused as where to do it at? Between the 1/2 nail spots and what size screws? appreciate your response!!
The answer about screwing to the joists versus the subfloor plywood is: it depends. When the subfloor is sub-par and I am installing 3/4 plywood over it, I will often screw both to the joists AND to the subfloor. In your case, you intend to install 3/8" plywood over 1/2" plywood. Hopefully you are not trying to tile over that combination, which would not offer enough stiffness. The 3/8 plywood offers almost no structural benefit and if you tried to screw that into the joists you would find that it buckles and bends. You are only installing a spacer with the 3/8" so screwing to the subfloor plywood is fine. You may have trouble doing that, even, since the 1/2" plywood underneath offers little resistance to screw withdrawal. Depending on the finish flooring you are using and the ability to do a transition strip between rooms, you may want to bump up to a thicker plywood.
@@enduringcharm tysm; no title just putting laminate down after pulling up a very thick, heavy, real oak hardwood floors. Would going up to a 1/2 inch on top be any better or would be the same in terms not really adding any added strength? And would nails be a better option than screws into the subfloor ? (Sorry for all the questions, 1st time home buyer doing it myself, I have very little experience here)
Laminate will be fine, that can withstand quite a bit of flex. If you can jump up to 1/2" or 5/8" plywood I would do it. The 3/8" is so thin that the screws could even deflect the plywood or pop right through. You'll have an easier experience if you go 1/2".
For a corner shower, is it best to set pan on subfloor or on the finished floor?
The pan is set on the underlayment--the second layer of plywood. I have just the video for you: ruclips.net/video/PUTyeD-jyeY/видео.html
Thank you!
Thanks for the explanation. I recently gutted my shower due to a leak and discovered that my subfloor was nothing but a few untreated 2x6 nailed to the joists..
You mean the 2x6s were laid flat on the joists, or that they were installed as blocking and you had no subfloor?
@@enduringcharm they were laid flat. Would you suggest I take them out and lay a plywood subfloor over or simply place a cut out plywood on top of the 2x6?
Well, I look at a remodel as a chance to address all the mistakes of the past. Ideally, you should have both subfloor and underlayment plywood layers under the tub and the entire bath continuous in this manner. So, yes, I would take out the mess that is there, and lay down 3/4 plywood over the joists as a start and then whatever thickness of underlayment you can manage on top of that, given the height of the floor in the adjoining room. I have a video with tricks for that transition. I know it can be tough getting larger sheets of plywood up into a small room, but the larger you can manage, the better. The underlayment should overlap the subfloor seams. After you get the tub or pan installed, the cement backerboard (if you are doing tile) will go up to the edge of the tub or pan.
Actually, I was assuming that you are doing an entire remodel, not just trying to repair the shower area. Is that the case?
@@enduringcharm, your assumption was correct. After taking out the shower we decided to do a whole bathroom remodel. Currently tile is installed (poorly from original remodeler). Planning to install lux vinyl
my floor is 5/8 x 2 tongue and groove right on top of the joist , no sub floor. I plan to cover it with paper then 3/4 ply then engineered floor
If you will be using an engineered wood or vinyl finish floor you are already in better shape than if you would be using tile. Wood or vinyl will be more forgiving than tile. Putting down 3/4 plywood should be fine, although you may need to use a belt sander or other tool first to take down any high spots on the T&G wood. Try to get that as flat as you can and secured so that there are no squeaks.
Thanks, this helps.
Do you ever glue your plywood to the subfloor. I have read several mix reviews on this on many forums. My situation: currently have 1/2" subfloor on upper level and squeaks pretty bad. I had a contractor come out and they recommended glueing 7/16" plywood and then driving screws threw plywood and subfloor to joist to "sandwich" together. What are thoughts on this? Couldn't I just add screws to current 1/2" subfloor to eliminate squek and then screw plywood to subfloor and not worry about screwing to joist?
Squeaks can be be from many different sources--nails sliding against the wood, wood sliding against other wood, etc. Screws do generally hold up better than nails as far as avoiding squeaks. If I understand you correctly you believe you have 1/2 inch plywood as your first layer over the joists? That would be unusual and unfortunate if true. 5/8 inch was used in early days and 3/4 inch is best. Are you certain it isn't 5/8? It's best to identify the source of the squeak first, since it could even be the joist(s) itself. Screwing the first layer (subfloor) down is a start. I generally do not use glue between layers, partially because I want to give the next guy a fighting chance. Gluing the subfloor to the joists is good practice, but it's too late for you on that count. If you get the subfloor squeak free, then screwing the underlayment to that should be enough.
@@enduringcharm The current subfloor is a true 1/2". Joist spacing is 16" and hoist are 2x8 or 2x10, can't measure yet but can see in a crack. I wasn't worried about having to remove glued floor in future because it's for bedrooms and I'm laying laminate down. Could be changed to carpet easily in fututure if someone wanted to. Don't see a reason to ever remove since I'm building up to reinforce original subfloor. I was thinking using 1/4" to build up to meet minimum 3/4" recommended thickness for subfloor. Do you think that should be good and what type of plywood do you recommend, ish, cdx..etc.
Well, it's tough for me to make a judgement without seeing the circumstances, but a 1/2 inch subfloor is doing almost nothing for you. It will flex and allow the joists to flex too, which may be once source of your squeaks. If you have the height available in the floor of the adjoining hallway or room I would install 3/4 plywood over what is there. I'd screw down the 3/4 after screwing down the existing 1/2 inch. I'd still skip the adhesive, which is likely to cause gaps between the layers and contribute to future squeaks when the gaps eventually sag and touch.
Corey-- there isn't a simple answer. Whether you screw through the subfloor into the joists or not can depend on the details of the situation. Just today I installed 3/4 plywood over old diagonal boards and chose to use long screws into the joists and shorter screws into the boards. Otherwise, the diagonal boards would provide little support. In your situation I would typically not screw into the joists, but use a fairly tight pattern of screws into the first layer. However, if I found that the first layer had been hacked up into small sections, or looked otherwise damaged, I might choose to go in to the joints as well.
Hi Preparing uneven subfloor for tile by adding another layer of plywood and then Detra but the floor is not level should i first use self leveler and then the plywood or installing the second layer of ply wood and then self leveler before installing Ditra and tile ? also My house is build in 1994 if i use the thick ply wood u use the floor get to high compare the the rest of the house and it would not be easy to find a translation i intend to use one Cm underlayment and then Ditra and then the granite slab {natural stone } any suggestion thanks
Level and flat are two different things. Level is important for placement of a tub or shower pan, but it's not that important for tile. Flat is very important for tile, though. You don't mention how far out of level or flat your floor might be. To need a self leveling compound the problem is generally pretty bad. The self-leveler goes down before a second layer of plywood. I'm confused about your mention of a "one Cm" underlayment. Do you mean a one centimeter thick plywood? The closest I know of to that would be 3/8 inch (actual 11/32). Such a thin plywood would add no strength to speak of, all it might do is offer a smoother surface and additional height. Generally 5/8" plywood is the thinnest I'll go for the underlayment, although once or twice I was forced to use 1/2". If getting the floor flat is your only concern, you may be able to make up some waviness with the thinset under the Ditra. But, I'd need more information to offer specific advice.
@@enduringcharm hi thanks for reply so the floor is not flat when i use leveler i see it is like a roller coaster the plywood i meant 1/2 inch by adding that new plywood the thickness of my floor get to 1.19 inch and i am trying to install natural stone so do u think is that good enough for stone ? and the other thing if i install the new plywood and than i use self leveler compound does it matter ? the reason i am asking i want to glue and screw the new plywood to sub floor if i use self leveler first than i wont be able to use carpenter glue also the screw would not crack the sell leveler if i install the plywood after ??thanks
Okay, so flatness is your concern. What does "roller coaster" mean, are the dips more than an 1/8 inch? Are the joists on 16 inch centers? Is the subfloor, the first layer of plywood, 3/4 inch? If not then it may be better to replace that than to try and make it flat. Gluing the underlayment to the subfloor really won't buy you anything. You need strong material to span the joists and not deflect with the weight of the tile. If there is one area that dips due to the joists you could certainly use self-leveling material to flatten out that dip. But, it will add no strength. For a heavy tile you need strength and stiffness. Also, for larger tiles over 12 inches in one dimension the flatness of the floor becomes more important.
@@enduringcharm The dips are more then 1/8 the joist are on 16 inch and the sub floor is 3/4 thick
Self leveling compound should be used when you have a severe falloff in an area, perhaps a corner that drops off by a half inch or three quarters of an inch in a tub area. I would be very surprised indeed if you have 3/4 inch plywood sagging in-between 16 inch centers. My guess is that you may be seeing high spots at plywood seams where a joist or beam is higher than neighbor joists. If you are using a large format tile they can rock on top of high spots like that. Sometimes a belt sander can be used to knock off the high spots like that.
If the whole floor is relatively flat but you are just seeing high spots or a few areas of minor sag, then I would knock off the high spots and then put down 5/8 or 3/4 plywood as underlayment. If you have a height issue with the adjoining room you can install a tapered marble transition on top of the underlayment, then install the ditra and tile up to the transition. You might also consider skipping the Ditra and using 1/4 inch hardibacker. Screw the second layer of plywood to the subfloor every 6-8 inches and check for squeaks before you go further.
I have a 3/4” diagonal plank subfloor on 16” joists in my bathroom. My hallway floor is 3/4” hardwood, I really don’t want to use 3/4” plywood with 1/4” hardie due to the height of the threshold. Think I could skate by on 1/2” plywood with 1/4” hardie? That would make 1-1/4” base for the 12x24” ceramic tiles. Please help 🤣
While the condition of the diagonal boards and the span of the joists are part of the equation, I can tell you are already asking for trouble. A 12x24 tile, which is popular these days, is a large format tile which demands a flat substrate with little flex. If the substrate is not flat you'll end up with lippage, where one tile edge is slightly above another. If you don't eliminate flex you'll get cracked grout lines or even cracked tiles. With a large tile there isn't a lot of grout line opportunity to hide a wavy floor, either.
1/2 inch plywood provides almost no help as far as flex because it has little rigidity. You'd be relying on the diagonal boards for rigidity and the 1/2 inch plywood would potentially smooth over some board gaps. That's not much foundation for new tile. I'd prefer to see at least 5/8 plywood, generously screwed, then either the 1/4 inch hardibacker or potentially Schulter Ditra. Another option is to remove the diagonal boards and replace with 3/4 inch plywood, followed by 5/8 ply. Also, if you can use porcelain tile instead of ceramic, you'll have a better chance.
There are tricks to ease the transition so the height issue isn't as bad. See my video here: ruclips.net/video/vQKFdO65Qz0/видео.html
@@enduringcharm Thank you sir, greatly appreciate your help and time! I’ve actually got some 19/32 plywood I originally bought for the job, was going to take back this morning and get 1/2”... glad I opened RUclips first 🤣
So the 5/8” plywood + 1/4” hardie and I should be fine? I really don’t wanna rip the subfloor out 😩, hell I may just put down 3/4” ply and some damn laminate or something so I don’t have to worry about it 🤣... thanks again for sharing some knowledge. The video you sent me was very helpful as well, I’m going to watch a few more now lol... def earned my sub brother!
Without being there I can't give a firm answer, but if the diagonal boards are in good shape (not cupped or cracked), and the joist span isn't a great amount, you'll probably be okay. Screw down the diagonal boards first and use a belt sander to take down any high spots. Install the 5/8 plywood with high quality deck screws every 8-10 inches. Check that for flatness and excessive bounce. Then install the hardibacker, possibly using the transition trick I showed in that other video.
I love is video, awesome. Hi, I’m want to install Carrara Marble 12 in. x 24 in. Peel and Stick Vinyl Tile to my bathroom. At the moment I only have subfloor. I’m sure I need something between my subfloor and vinyl tile I just don’t know what, please help me
Peel and stick is not something I use very often. It's a budget choice and shouldn't be expected to last very long, especially in a bath. To install it, you'll need a very flat and smooth underlayment. Lauan plywood is often used, although you might look for specialty versions of this plywood sure as SurePly, which are specifically designed for the purpose. The 1/4 inch sheets are put down with stainless steel staples and the the seams are filled so they don't telegraph through the tile. You can tile right over this, but I would suggest priming the entire surface first and letting that primer cure for several days before applying the tile.
Thanks so much for this video! I've learned more from your video and your reply comments than I have elsewhere while researching! I am redoing a small bathroom (35 sq ft) in our 60s rancher. The 5/8" underlayment has some water damage so I am replacing that and hopefully leaving the 1/2" subfloor beneath (plywood maybe). It looks to be in good condition when I look up at it in the crawl space. My question is.. will 1/4" Durock backerboard suffice for tiling if I have the 1/2" sub + 23/32" underlayment (about 1.2" total) ? I plan on doing a layer of thinset under backerboard as well. The tiles are hexagon shape approx. 8x8". Thank you!!
There's another factor to think about, which is the joists. If your floor joists are long, or not very wide, you can get more flex and movement than if you have shorter lengths and wider boards. Tile and flex don't go together very well. You have to make a judgement call, but if you feel a lot of bounce in the floor when you walk, you may have issues. Fortunately you are using a smaller tile, which will fare better with movement because of the additional grout lines. Anyway, my advice is to use the thickest plywood underlayment you can manage given the height of the floor in relation to the adjacent hallway. Sometimes you can cheat a little by ending the backerboard at the edge of the door threshold and installing your marble transition on the plywood rather than the backerboard. That buys you another 1/4 inch and if you get the right thickness of marble it will be level with the tile. I'm not a fan of Durock at all. It has no stiffness or structural rigidity to it. I'd highly encourage you to use Hardibacker instead, and just use screws--no thinset beneath. This will allow a little bit of decoupling movement. Or, if you really fear that movement will be an issue, you could use Schluter Ditra instead.
@@enduringcharm Thanks so much for your reply and all this helpful info. I think I might actually use Schluter Ditra based on your recommendation and after looking into a little more. If I use backer board instead I'll definitely use Hardie. Thanks again! I am subscribing to your channel
If you're remodeling and find a subfloor already have an underlayment on top, would you add another layer to it or replace the entire underlayment to improve the strength of the floor?
You've touched on a pet peeve of mine! People do put new layers on top of the old, including layers on top of finished flooring. Professionals do not! The only time I would leave the underlayment alone is when it is perfect shape due to the type of finish flooring originally installed. For example, if you had linoleum or vinyl sheet flooring that was installed on top of 1/4" luan plywood. Sometimes you can take up the sheet flooring and the luan plywood and discover that you have perfectly preserved 3/4 or 5/8 underlayment on top of the 3/4 subfloor. In that case you could add 1/4 cement backerboard and then tile, to give a common example. For most instances, though, you will find a beat up plywood underlayment that had tile over it, or something like that, and you should remove all the layers down to the original subfloor and build back up. Often the original layers were nailed, not screwed, which is also not ideal. In my work I always take up the old layers down to a clean starting point and build back up, and I use screws to avoid squeaks.
+enduringcharm Thanks! That answered my question. My underlayment has cracks and thinset marks all over it. I guess I won't be reusing that. If I put down plywood underlayment, can it be thicker than the actual subfloor?
As a general rule, thicker is better. Ideally you'll have two solid layers of 3/4 plywood and then you can put down your finish floor system, which may include cement backerboard and tile, or wood, or whatever. However, you have to watch the adjoining room. Measure from that room's finish floor to determine how much height you have--you want to have the two finish floors match up or come close to it. With that measurement you can determine how thick you can go with your underlayment.
@@enduringcharm how much thicker can you go with your floor compared to the adjoining room and it be reasonable.
I have a problem where the finished floor in my bedrooms are the original tongue and groove three-quarter inch plank flooring, and my entire bathroom flooring rotted out. I replaced with three quarter inch pressure treated pine in the bathroom for stability and this made the joining bedroom level. The problem is I'm wanting to add tile and from everything I've seen and researched the best idea is to add half inch plywood underlayment and then a quarter inch Hardy backer before I tile. I'm thinking this is going to make the bathroom floor way larger than the adjoining room. What solution should I use? Thank you for your help!
@jeremiah see this video, which I think will answer your question. ruclips.net/video/vQKFdO65Qz0/видео.html
At 2:02, how necessary is the advice on screen here?
If you are installing tile, then getting these details right is critical. if you are installing something flexible like wood flooring or laminate flooring it may be less critical. I'm guessing you need to see this video too:
ruclips.net/video/vQKFdO65Qz0/видео.htmlsi=_PZXo579ziQhMjKl
Do you have any videos on how to level underlayment on an existing subfloor. Working on a house built about 1920 and the subfloor is diagonal shiplap and its very uneven. Also wondering what type of plywood to put on top of the subfloor.
Diagonal boards can be a real challenge. The boards themselves can become cupped or twisted and the edges where they line up with the next board often create a lip. One solution is to pull it all up and start over with plywood and I've had occasion to have to do that. Short of that, you can work the surface foot by foot to level and flatten it. remove protruding nails, and use a belt sander and/or planer to bring the boards closer to flat. Self leveling cement is generally not a good option for diagonal boards because it will crack with the movement of the individual boards. When you've done the best you can, install a layer of 3/4 plywood using screws, or the thickest plywood you can manage.
enduringcharm I don’t think you understand how amazing the timing of your comment is. I am dealing with this exact situation with 1 x 5 boards for a subfloor. Old house so the boards are curled up or down with some water exposure. Pulling them up isn’t an option so been trying to figure out what to do to get level them out for tile.
enduringcharm do you think it’s ok to use staples to connect the plywood underlayment to the subfloor or are screws necessary? I’ve heard there are screws with tips that cross to give extra grip. Also would you put some material in the joints between the boards? Someone suggested liquid nails. I thought kitchen and bath caulking to inhibit mold growth.
Screws are preferable, especially in this situation. The diagonal boards will want to move with the seasons, and staples will eventually work loose. Screws simply have better holding power. A high quality deck screw will work fine. As for caulking between the diagonal boards--not necessary and not helpful. The wood will continue to expand and contract and the caulking will do nothing. What you may want to do is sandwich a layer of rosin paper or tar paper (30# felt) between the diagonal boards and the new plywood. It may help prevent squeaking between the two layers and also keep them separate as far as any future moisture.
@@enduringcharm is it not recommended to shim the plywood over the diagonal subfloor.
Backer Board which is attached to the subfloor(s) is in point of fact, not de-coupled.
This could be clarified. Some manufacturers do specify that the backerboard be adhered to the underlayment using thinset mortar. In that case you are right--there isn't much decoupling taking place. However, I just use screws to attach the backerboard to the underlayment. In that instance, there is some decoupling because the movement of the underlayment can be absorbed by the play in the screw connections. I mean, it's not a floating floor, but some movement is absorbed by the assembly. I have seen many tiled floors without this method and there are cracked tiles right down the line of the plywood underneath.
@@enduringcharm Your points are well taken!
Thanks