Good building practice in Finland is to insulate the basement from the outside. We don't have many basements nowadays because it's cheaper to insulate the perimeter of the house with EPS or XPS rather than to build the basement below the frost line. Also post WW2 basements had inadequate drainage so there were a lot of issues with flooding so basements have bad reputation.
this. plus... doing a building with eps around the peremiter now. it's like -10*C for a month now... was sprayed -5*C. no heating what so ever, and it's been a constant 5*C inside. i imagine if it was underslab insulation, none of that free geo thermal heat would come through and it would be -10*C inside right now.
I'm building a new house now. We just finished the foundation. My wife's uncle is doing the site work and he's pushing hard for me to insulate under the slab before we pour in 2 weeks. I've been fighting against it thinking its a waste of a few thousand dollars. This video has me re-thinking my position.
From what i have seen and heard it is best to not have the foam directly to the concrete. They make a special drain mat you are supposed to attach to the wall behind the foam to allow the concrete to breath. The same style drain mat is attached to the outside of the foundation to direct moisture to the drain tile at the footings.
That "interior weeping tile" solution is designed for basement walls that still have some water leakage from outside. In such situations it is better to permanently fix the water infiltration problem on the outside of the wall. When you can't dig up the outside on a cost effective basis, e.g. due to a shared driveway with a nearby neighbor, then the interior weeping system can be used with a connection to a sump pump pit.
@@paulsp6371 I have done a lot of remodeling on houses that have open cell and closed-cell they have been holding water and rotting box plates sill plates top plates and is a climate for post beetles and termites what's on paper is one thing what's going on in the field is completely 100% true Owens Corning opening letterhead stated they will not get involved with spray Foams because they feel that it's the next asbestos material and we don't have enough technology to understand it at this point
@@gaylehiner9511 I could not find that letter. Do you have a link? I have seen another video where the foam needed to be removed/replaced due to poor application and serious air quality issues. Risky when you see some of the people that are installing this stuff. Not all are quality people.
German Architect/Construction Engineer/Prefab Construction Contractor here. Your videos are very informative about the US construction scene. But surely we wouldn’t ever do, what u guys are praising here. I advice anybody to check out the Eurocode Building Code on theese issues (available in Eng!). They are mostly created by German universities and Institutes, so they are pretty sound. For example interior insulation is something, everybody try’s to avoid for good reasons. U have literally no active Thermal mass and u will always have a dependency on artificial ventilation/dehydration methods, since there will always be a humidity problem as well. Also nobody is using oil based Foaminsulations in the interiors, for health reasons (except for slabs without possible connection to the air). IF u realy need to have a interior insulation, you always go here for a mineral based insulation like foamglass, which can be plastered with lime-cement plaster (natural desinfection of the wallsurface) and is beeing able to „breath“ humidity in‘n‘out to a certain degree. But if u build new, always try to avoid this stuff by using perimeter insulation on the outside of the basement, incl. a drainage plate and geotextile against the refill.
I’m a spray foam contractor in Canada and we usually spray foam on top of the grave with closed cell foam it acts as the vapour barrier as well as the insulating factor. The big benefit of spray foaming rather than using insulation board is if there’s any voids it fills them in rather than spanning over
@@zzzzzzzzzzzzzzzz8635 think about it your right.the company's get the spray foam in large quantities at a discount then stiff the customers because they can.
What happens when the foam starts to degrade????? I don't get it, a foundation should last 150 years at least, that foam is good for 15-20 years... then what. Your foundation will either be floating and weak or completely collapsed... no?
About to start work on a basement remodel in mixed humid climate. 50s house no slab insulation. Laying down deltaFL taped air tight - 3/4 iso foam - cement board. Steel studs 1” from wall, 2” closed cell up over band joist. Watching this - sounds like we’re pretty close. Matt and Steve, thank you.
keep in mind, a closed cell insulation, below grade, on an exterior wall is illegal in the Midwest which is why it is also illegal to use a vapor barrier or in some cases, not even faced insulation under those circumstances. The moisture needs to be able to evaporate vs. being trapped.
Yep, that wall has 2 sides, and there is no way to guarantee that they can keep moisture out of the concrete wall, thus it has to be able to dry to the inside.
I wondered about this...check some of the articles Building Science Corp and Fine Homebuilding about why this works. According to Joe Lstibirek, PhD, 3.5” of closed cell still has enough vapor transmission to allow it to dry to the inside. Anything over that could be an issue.
@@Shad0wC0mpany2 That's because I believe in airtightness, water management, and surface temps of condensing surfaces - with that vapor doesn't scare me at all
Many homes in New England have issues with radon. It's easily solved with a mitigation system that could have been installed in the basement and home walls before this project was wrapped up. it's basically just a vent tube with an air pump.
I'm confused about the closed cell on the basement walls. In the floor you have EPS then poly then the slab. Why not have EPS and poly on the outside of the walls to decouple the foundation walls from the earth outside, insulate the walls, and keep the moisture barrier on the outside of the walls instead of the inside. Aside from the thermal issues, it seems that hydraulic pressure from moisture coming through the foundation walls is eventually going to push the closed cell away from the walls, and pool water between the walls and the foam. Looks like the right idea in the floor, but backwards in the walls.
Patrick It's a terrible construction, but the US can't build concrete housings. Look how it's done in Germany, they know how to build massive. Never use sprayed PU foam on the inside. It contains harmful substances. Keep the concrete on the inside, it will hold the temperature and moisture constant for good room climate.
My guess is the outside foundation walls were also waterproofed. The issue with eps on outside is in cool climates the earth expands and contracts and eventually will destroy the foam. This is why it is now required in many areas to have a 6 mil Poly between earth and eps to act as a slip but this never works in reality. The technique they are using is a very good and cost effective solution if building this way. I only build with icf which solves all these issues with ease
@@paulnovak833 How is the foam exterior of an ICF block any more resistant to those foam-destroying forces than sheetfoam or sprayfoam applied to a block or form-poured basement wall?
Biggest mistake I made in my new house was not insulating under the slab! The tile floors in the bathrooms are uncomfortable in the winter due to cold radiating through the slab. Floor temps get down in the low 60's which makes the heat have to run more often. Great video!
@@stevenbaczekarchitect9431 LOL! I'm into Monolithic Domes and there the concrete is exposed on the inside. Why? Because of 3" of polyurethane insulation on the outside. It's like eating a Goose Down jacket to keep you warm... No, you put the insulation on the OUTSIDE.
dig out the perimeter of the slab, and slap some EPS boards around it. it'll do a good enough job, because soil is insulative and a thermal mass. you have infinite insulation on the bottom; it all escapes SIDE WAYS. the further down you run the eps boards, the more insulative it will be. varies a bit of course. say your soil is sand; sand has a r value of 7 per foot. run the EPS 4 feet in the ground, and the heat will have to go through R28 on the way down, and then another R28 on the way up to leak out to the surface.
Great video!! I have designed basement slab insulation systems and never stopped to consider WHY we put the poly on top of the EPS. Makes total sense! Just say no to "iceberging"!
@@rotaxrider in my area (central canada) I have never seen a code showing specific order... I typically do poly on top for this exact reason... Building inspectors never question it.. they just want to see proof of foam thickness if the plans called for a specific thickness..
Tell me about the cross section of 2x material under the floor joists above. Where I live, most contractors insulate between the floor joists and drywall directly to the floor joists above (uusing blocking to stabilize the floor joists.). What is the benefit of the 2x lumber attached and running perpendicular to the floor joists I see in most of your videos? I live in NE Pennsylvania.
my slab currently is sitting between 72 and 75, i'm mid remodel and so some portions of my concrete walls are exposed on the inside that are above ground outside on the side that gets afternoon sun, here in the middle of the night that section of concrete is just shy of 79 and I can say for sure that concrete is not insulated on either side. current outside temps around 70, yesterdays high was 90-93 and ground temp for my area is around high 70's at 8 inch deep
How do you know where the moisture is condensing in between the closed-cell foam and the foundation wall? Seems like trapping moisture in there might cause degradation of the foundation wall over time.
Matt, love the videos. Q: Is there a separate radon barrier that turns down at footing in addition to that 10 mil turning up the wall? Or does the CCF keep the gasses from infiltrating the basement?
Just a few comments from living north of 50 degrees latitude: (I'm not really an expert, so please feel free to disagree.) Bat insulation doesn't perform as well in basements as above ground, because the difference in temperature at the top and bottom of the foundation causes vertical air movement within the bat. In the dozen or so basements I've torn up, there are always some spots that have been continuously wet, even with proper vapour barrier & moisture seals, drainage, etc. Any kind of hollow wall construction in an exterior basement wall in a bathroom will cause problems. I prefer to attach foam board insulation directly to the foundation wall and drywall to the foam for these. I've only seen sub-slab insulation when there is in-floor heating, with the exception of one house about five hours north of Toronto that had full-height south windows that heated the slab in the winter.
This guy Steve, along with you Matt are absolute Geniuses when it comes to building super efficient, strong and safe homes ! I live in Ct and used to do insulation from the age of 18-27, and what a huge difference from then to now. This technique is beyond interesting and valuable and the way this house is being done should be a benchmark for all builders, thanks for showing and if you have anymore videos of this place, please show them. Thank you.
I worked making fresh salsa for several years. We ran our production line at sixty degrees and operated out of an old freezer warehouse. We chose the building exactly for that reason. The floor and related substructures were probably a little over four feet thick. Concrete, foam and stone, then another series of concrete, foam and stone. Pretty impressive construction.
Awesome educational material, here given by two guys who are "national treasures" in my opinion. So no disrespect intended by my following comments. I am deeply grateful for EVERYTHING you do, and publish, so the rest of us can WATCH and LEARN. Especially, thank you for the warning of the "iceberg" moment that will wreak havoc if layering of building materials is mindlessly wrong! Meanwhile: 1) There is no mention of how deeply placed, below grade, this basement lies. 2) There is no quantification of the hydrostatic pressure exerted upon anything. 3) Is this on hilly, or flat, terrain? I've seen another of Steve+Matt videos, shot in Texas, where the surrounding land was shown, while a huge ground-water remediation project was poured. Egad that was awesome and mindboggling, to see that such countermeasures even exist. So many people (here in SoCal) just ignore geological issues. Not to mention all the SF-Bay people who live atop a powder keg... the San Andreas Fault. 4) I love the 10 inches of gravel, and the mention of French drains etc., in other words, this is a comprehensive solution; but: 5) If that gravel ever gets silted up, by any means over the next century or two, then really nasty things are gonna happen; so 6) Anyone who believes in, or uses, dry-well-type methods of sub-foundation water removal must contemplate the importance of all those air gaps between the gravel pieces. The gravel might hold up the building, but it's those air gaps that fill with water and allow an underground river to flow. Thank you for considering my comments.
Insulation outside the slab is best, as the thermal mass remains inside the home. It’s why my 3600sqft brick Victorian only need 4 tons of in SE Iowa cooling despite tons of windows and no insulation. It just changes temperature too slowly. Most AC runtime is shifted to nighttime as the brick remains warms for hours. In the hottest part of the day the brick is still warming up.
From up north, too bad more builders don't insulate properly. Why not insulate on the outside of the basement concrete walls? Provides a thermal block and keeps the basement and main level floors way warmer...
I'm planning to (owner) build a home in northern NH next year and want to achieve a very high efficiency level. All these videos are going to serve me well. Very much appreciated.
Daniel, tread lightly. Demand MSDS sheets on all foams you consider. Most off gas, killing anyone inside during a fire. Many breaks down from the elements and time, eventually turning to dust. Some shrink as much as 36%. Others detach when sprayed on concrete. In short, if any of these problems concern you, it's best you get it in writing. If they can't show you an "aging test" or off-gassing test or shrinkage test or loss of R-value test, then assume they can't pass one.
@@larrymaloney877 Thank you for that tip, that makes complete sense. I'm guessing that extreme temperature changes like we have, would only worsen those issues. I'm also very suspicious of the tapes being used to seal exterior sheathing/foam. Unless it's chemically bonding with the substrate, I don't see how that could last a century or more.
You can insulate after. Insulating pumped screeds are available now. I wouldn't bother personally though. It's much better to pour concrete on grade than foam that will creeep.
Christopher, my thoughts exactly.. In the white north I don't know why would anyone build basement out of anything else but ICF... beats me.. O hold a second, I think I know.. TIME.. :) :) Everyone is builder these days and quality doesn't matter anymore.. Just this past January I saw a builder doing following: Day 1. - temp outside = -25 deg. C - dig a hole for basement Day 2. - 4 - temp outside= -25 deg. C - forming company doing forms Day 5 - temp outside = -25 deg. C - cistern and pump on site pumping concrete Day 6 - temp outside = -25 deg. C - forms are off by the way, no heating whatsoever was done... Now that concrete doesn't have even 10% of bearing capacity and then people are surprised that basements crack. That concrete froze the minute it hit those cold forms. I'm in the process of building my own house and it's ICF all the way to the roof. I'm not saying that everyone has to do that but for sake of insulation/thermal breaks, stable foundation etc. etc. use ICF... Building in Ontario these days is a big joke and consumers have no idea, they just keep buying..
cost is the biggest factor, cheaper and easier to just spray the wall later. also tighter this way since the spray foam wraps into the floor band
6 лет назад+3
That's what I did, (use ICFs) 18 years ago. I also used form-a-drain to pour the footings, and french drained the footings, inside and out. In western Washington we have very little radon, but that would also drain away any radon, as radon is 7x as heavy as air. The idea of insulating the slab is, at best, controversial, as the slab is a heat sink. If the heat can't escape sideways, it will just come back up into your house. My foundation walls are 4' deep, as I am in a wet location. With insulation 4' foundation walls, sideways movement of heat very unlikely.
BenjaminFranklin99 You built a good system, best is to insulate below slab because heat always goes to cold, i.e.. interior temps 68 f and grade 4' down 60-58f thus constant drain of heat to grade. The biggest factor is wet soils providing better conductivity to concrete and greater losses.
@ Yes that is the exact same system i use as well. The difference between regular forms and ICF and form a drain is that ICF can be done by anybody. In my personal home I had such a hard time with local ordinances that i just raised a 2x4 wall all the way around my basement. My spray foam guy went ahead and foamed it with rest of house so my basement is super insulated. I would never do it any other way.
My personal notes: 1: can rebar Concrete foundation walls be poured with the below grade rebar basement foundation slab as a monolithic pour to prevent air gaps? 2: for my 2x8 wall frame beams, I must learn from this video by distancing them a few inches from the concrete wall so I can pour closed cell foam exact same way as is taught to me here in this video. 3: Why does he say the walls aren’t structural? Are the concrete walls the only structural component? 4: Steve also like me thinks it’s a good idea to have a hydro break aka he pours 10 inches of leveled stone with a perimeter drain running around the foundation so that water never is in constant contact with the foundation like most houses. 5: Above the stone but under the concrete he has 4 inches of a special Type 9 EPS styrofoam that is rated for at least 25 PSI so it won’t break when the concrete above it is poured.
Thank you for insulating houses and basements and putting unfaced insulation in and covering with plastic it will keep my business going forever due to all the mold build-up you builders keep doing her and I'll just keep making my millions thanks
Being a remodel of a basement, the closed cell foam makes sense. However, if this was new construction why wouldn't the goal be to apply the insulation to the exterior prior to backfill? This complements the use of insulation under the slab. I plan to use a rockwool product because it also deters termites and does not degrade in the presence of moisture.
Also see the Insuladd interior paint additive. A guy using it inside a boat told me about it, to take up less space for existing construction. It is made from ceramic beads, a byproduct from burning coal.
I'm just doing my basement walls. spray foam was going to be about $7000.00. I put R28 batt insulation in for $1200.00. I did get the rim joists sprayed for $1700.00 so it cost me $2900 instead of $8700. The house walls are R24 and the ceilings are R55. We have triple pane windows too. I put rigid foam under the concrete floor which has heating pipes in it. It would have been good to sprayfoam but $5800 will buy a bunch of heat. Sometimes you have to do what you can afford.
I’ve got 2-3 feet of stone with tile in it , Polly and 6” of concrete on top . My coal stove is in the basement and yes it takes a day or two to heat everything up but one the concrete is warm everything evens out . In the summertime you put a box fan on the floor and it blows across that concrete - your gonna freeze ! Blankets in August !
This concept is awesome, making that basement air tight. Out west here in Colorado and SD we have issues with Radon Gas, I would think this would negate the need for a radon gas removal system saving a ton of bucks.
Radon (and radon mitigation systems) is pretty common in Boston area. I'm sure the building the foundation this way is more expensive than radon mitigation. And radon seeping through the concrete so it would need to be installed anyway.
I have an older home with cinder block walls that have seepage. I don't think this would be advised for someone in my situation. I had to break concrete and run internal drain tile and drill weep holes at the bottom of the block.
When its new construction it is less expensive to do these projects. Also, when your electricity bill for a 2000sqft house in New England is less than $200 in the winter it will be well worth it.
How much is it worth to have the room downstairs in your basement not cold if you actually want use it. I know from experience it is a real drag to have it cold. I did the math with some quotes and it would never "pay" to insulate the room from savings but it would make the room pleasurable to use versus having it virtually unusable. Of course in the summer that room is the best in the house, always nice and cool.
interesting twist on closed vs open is if you have a cinder block foundation you should think about open cell. it will potentially allow the moisture to move which could save the block and mortar from deteriorating (assuming a retro fit old block foundation which may not be well sealed on the outside.
The slab looks like it's floating. It appears as if there is a small (one or two inch) gap between the gravel and the foam layer, with the concrete poured right on top of the foam. How is this? Or is it that the is foam resting right on top of the gravel and the gravel has been moved away slightly from underneath the foam in the cutout you used to show the layers? I can't figure out why it appears this way, and if there is any significance at all.
I love the budgets Steve has to work with, my clients don't have the $'s for these luxuries also the loss of space would be problem for many referring to the shots of the double framed. I do love all he does, I just wish my customers had the money.
Todd, it is always a challenge to get clients to see the value. Most of them are not knowledgable. It is our job to make them see the light, and I know this, they ALWAYS have the money
Steve... they don’t always have the money. Not unless they are building custom with a finance of $850,000 CAD or more. To add all that extra care & work would be about $20,000 where I live (on a large home). On a large addition say 18’x40’ it would be about half that just to start. Basically building costs about $100-250/sq. ft. And that $100/square is for traditional framing meeting code with cheap Home Depot cupboards.
I live in Southern Minnesota and think about foundations and slabs a lot. This video's slab insulation process looks more complicated than it needs to be, at least from my thinking. I've been thinking about a good six inches of sand that is leveled and compacted on top of packed earth. I would then lay down one inch of dense foam and pour my slab on top of that. It's just something I've been thinking about and I'm not sure it's a good idea. What about painting the outside of the poured walls with roofing tar and glue on one inch dense foam board before back-filling with gravel and sand, finished with clay and top soil.
Question on under slab insulation! Where there is a column that is carrying load to a footing, is foam usually capable of carrying through that load from the column to the footing? Appreciate all that you guys do!
Hey Matt, can you address any questions or issues people may have with their insulated slab cracking? Apparently many people doing this are having problems with their slab cracking all over. Any info would be great. Thanks.
The concrete cures too fast from the surface and shrinks faster than on the bottom. The plastic underneath the slab slows down the curing, since the water can evaporate only upwards from the concrete. Cover the surface with a tarp to slow down the curing.
The most common concern I had when I was in redi-mix was concrete being placed too wet. Contractors were known to ask for more water added on the job. While it makes it easier to work in the moment, the loss of cured strength and shrinkage cracks are high prices to pay. The above comment about the poly seal below requiring all of the moisture to migrate upwards bears true. Keeping the surface of concrete damp as it cures is never a bad idea.
This is one of the best videos I have seen on basement insulation. Is a sump required with this setup or would it be redundant? How would a French drain be applicable?
From what I could gather was to make sure moisture never came in contact. That gap provides an escape for any water through the gravel before it can reach the foam or slab. Not an expert and only speculating.
In the South, would it be better to not insulate on the inside of the foundation wall to keep the thermal mass of the concrete wall within the conditioned space?
I'm wondering which town outside of Boston. I build in central Mass and in the basement I need a fire break every 10ft to pass inspection. Usually either PT or Roxul. Also we usually have r18 minimum so would need another r3-4 not by choice. And sometimes when using closed cell we get forced to use 5/8 sheetrock or 1/2 blueboard and plaster also for fire. Thanks for visiting the area! 😊
Matt, I don't have a basement, and I'm sure as heck not a construction expert, but these are just so informative that I can't help but watch you ONnn the BUILD SHOW :D
Check out above Matt at end of video the closed cell insulation is pulling/shrinking away from stud. This would be a major air leak. An issue I always think of where spray foam is applied and soon after gyproc covers the wall and there is over time the shrinking insulation that is allowing the air to enter building. Should a vapor barrier (plastic sealed wrap) be installed and tape sealed as an assurance against this type of incident?
Fascinating ! Did I get this right?? 8-10" rock A french drain around the floor edge 4" foam//25 psi rated 10mm moisture barrier 4" concrete pour How deep is the basement?? 10-12'? What about plumbing/sewer? Thanks Matt !!
Very well done, I know with the stone, insulation and vapor barrier being under slab there is little chance of capillary wicking of water from slab/footer. My question is since you run the spray foam insulation up into the M joist do you fully cover the M joist or leave some exposed to the inside so that in case any water wicks up in can diffuse though the m joint into the basement so the m joist doesn't rot/mold?
I was wondering the same thing. If the M joist is fully sealed inside, but not insulated and sealed on the exterior, it will wick moisture and not dry during the northern fall-winter-spring.
Hey Matt, is there any chance you can do a retrofit video for us northern homeowners who want to insulate our basement floors? I think I'm going to end up doing r5 over some seam sealed dimple mat, then a plywood subfloor over that. It should be enough to stop vapor and condensation without losing too much height in a basement without high ceilings.
mikecampanella1990 - I’m an insulation contractor in Cleveland, OH and your approach is one that we recommend and use with excellent results. Don’t know if you’ve seen the articles about this on buildingscience.com but it is well documented. Go for it, good luck with your project.
@@torstenhansen4308 great man! Thanks for chiming in! I'm glad it's a successful option because it's really all that I can do with my current home without spending entirely too much money.
@@nc3826 the only problem is that the house was made already and in 1951. Lol. So, my only option besides digging the entire yard up would be putting foam on the interior. With everything having closed cell foam on it and a full vapor seal, water shouldn't be an issue unless there was a burst water pipe down there and everything is brand new pex, in an insulated space. So, I don't see that happening. Any insulation I use in the actual stud walls will be roxul due to its no mold and fire proofing for against the foam.
@@nc3826 well, I had asked about a retrofit for the house because it's a 1951 and I'm not tearing out the slab and I'm not insulating it from the exterior. I will be putting down a dmx subfloor with 100 percent seal, then foam. The plywood will be tongue and groove and most likely floating, anchored at all wall bottom plates so no shifting will happen. I did not use pex a because I didn't have an extra fee hundred dollars for the machine. All of my own joist are accessible and ran with a manifold. I'm not worried about them at all.
I was wondering the same. I used 2in xps directly onto the concrete walls then framed over that. I was also going to insulate in the studs after running my electric, but the floor is tricky. I found some vinyl flooring that is completely water proof and goes down like a pergo floor. Just curious what i could possibly do for the floor....
interesting idea that the spray foam in the walls. But how do you deal with any moisture that's coming through the cement walls? It wouldn'thow evaporate travel down to the floor? We've always been taught to make sure that there's an air barrier between the cement and the insulation specifically for this purpose and it seems like we're totally defeating that by using closed cell foam. Is this a complete Paradigm change?
@Joe Bears yes and if you don't have an exterior one and can't add one, you should put an dimpled mat on the inside wall and an interior french drain. Water management must be done correctly before putting any insulation. If you use a peel and stick membrane or any membrane for that matter on the interior side of the wall, it won't work. The water will push the membrane from the wall instead of pushing it toward the wall like when you put it on the outside. With enough time and hydrostatic pressure, it will unglue the membrane from the wall and you'll be back to square one.
Well the correct way to do it is to have membrane and drain, AND insulation on the outside of the basement wall. Yes in the dirt. That is how we do it in Scandinavia. But the slab thing is 100% correct and how we do it here.
@@72strand Some people do it this way in Canada too but internal insulation works as well. Plus, it blocks the footing from being a thermal bridge . You just have to be really careful to not allow your warm air to reach the cold concrete wall and hope that your concrete won't crack after many cycle of freeze and thaw. Actually, I think the better solution it's to put insulation on both side.
@Joe Bears the only way is too put foam under your footings. Some people do it in Canada but I would be worried about deflection personally. I would prefer to add some interior insulation instead or to not have a basement at all and have a shallow frost protected foundation instead.
I suggest ICF for the walls for that exact reason.. totally agree with slab.. I actually put mat underneath foam but my foam has locking edges to prevent concrete coming underneath...
What is the fire rating for the foam? In a foam insulated home, more folks die from deadly foam gassing during a fire than smoke or flames. Again, what is the published fire rating? Also, does that particular foam have a published test showing how it ages? On a personal note, I had a fire in my home recently, and fortunately, came home just as it started burning from a shorted extension cord in my dining room. I had one piece of 2'x2'x1" rigid foam board in the dining room along with two sticks of foam trim, all against the wall. (The product that simulated wood baseboard trim.) The fire was still small so I drew buckets of water from the bathtub to put the fire out. That bathroom is just across the hall from the fire but I had to step outside and BREATH, before re-entering because of all the gassing from that little bit of foam. A houseful of foam would be deadly in an instant! Even my little fire was terrifying. I can't imagine being in a foam home & having a fire. I was lucky to come home and catch it in time. There was little damage from the fire, just my carpet, and sooty walls. But the gasses almost killed my kitty and me. Again, what is the fire rating? Some products claim "will not burn." And truly, the foam doesn't burn. But it melts and off-gasses deadly fumes. What is the brand of foam? And please share brand's fire rating? It's been tested by a third-party testing organization. Where is their report? Please don't be shy!
Even fireblocking foam will eventually fail in the heat, so anyone who says "will not burn" is definitely spouting stuff that's misleading at best and an all-out lie at worst
@@Regolith86 , good point, Rego...electricity and water don't mix. My fire was a carpet fire, caused by an electrical short in an extension cord. When I walked in the front door, the house was full of dark smoke. I couldn't even see the flames so I worked the light switch and the power was off. The short had finally tripped the circuit breakers so no electrical current could flow. Besides, I unplugged the defective cord. Again, the only issues were the fires burning is several spots on my carpet and the fumes from the melting burning plastic. I tend to get windy when writing but did my honest best to keep this one short. I hope these details rest your mind. I even used an IR camera to find a hotspot inside the wall. But when I drilled into it I found a was a kitty on the basement ceiling girder below. The camera was showing her body heat not more fire. It was a valuable lesson. I won't ever use trim boards made of foam again. It shouldn't even be available..too hazardous. And I'll finally get around to adding a few wall receptacles to accommodate the new service I installed...no more extension cords. Several years ago I upgraded my electrical service to 200 amps. At that time I relocated the outside masthead and while installing the new meter I added an outside circuit breaker. I have a healthy respect for electricity. I once taught electrical safety as part of an electrical course I taught to electricians, maintenance personnel, and electrical engineers. My next personal upgrade will be replacing the conventional circuit breakers in my panel with the latest electronic versions. Some detect flash, arc, and leakage.
I remember when some wall to wall carpet products were pulled off the market, performing like Napalm in a fire before some insurance company flagged it. That was last century. Polysiocyanurate is the "go to" insulating product now, due to it's high (R 6.6) insulating value and it's ready availability and inexpensiveness. But it off gasses over decades (70 years?) to where it eventually has a low R value. So what is the design life of a building? In my book, they should last hundreds of years, so polysio-based products are out. The only substitute I know of is compressed rock wool. Being organic, it never changes and being compressed, it can be applied in some places where fiberglass can't, like onto concrete and I think, under footings. R 4 per inch means you need 33% more of it. But now we have a crisis; If we re-build all the houses in America properly, not using polysiso products (they are also a petroleum by-product), we have no chance of enough beneficial effect to help with the onslaught of Global Warming. If we use them, we contribute to Global Warming but will at least have some shelters that can weather whats coming. Obviously, we'll do what we have to so Polyiso products will be used predominantly. But the rest of the house is concrete and the design life of other parts is hundreds of years, so why add critical insulation that will fail after 70 years? Stick frame house yes, concrete houses, no way. Food for thought, we'll all be in tents before the end of the next century anyway.
@@refusoagaino6824 , With your prodding, I remember the foam carpet that poisoned the homeowners who used it. Foam itself was removed from the market in 70's because of formaldehyde. Today, it's still found in small amounts. But when we mention "foam" it has several meanings because there are so many different kinds. The weak foams, like pump foam, rides on the coattails of the better foams pretending to have similar qualities. Trusting homeowners, who want to believe they are doing the right thing, pay double for an inferior product. They don't see the shrinkage going on inside. High-pressure salesmen have to lie in order to keep the product on the market. Global warming isn't the consequences of poor insulating practices in the USA. IT's the direct result of gluttonous consumption of energy. Besides, there are very adequate, and affordable techniques and materials to retrofit existing homes with excellent insulation. It's just not foam. So don't use global warming as an excuse to burn more petroleum. We have the technology but the profit in foam drives marketing which is contrary to what planet earth needs. Politicians are about creating/maintaining jobs, not doing the socially right thing.
You could also spray foam the concrete walls and the top of the gravel all in one go. Should be more impermeable and air tight. 10" of gravel is pretty nice. I've seen lots of people only use 6". I guess it depends how much sand or clay is in the soil.
Lots of good ideas here. We vary somewhat from what's done here. Poly isn't used because it has permeability. Stego or Husky as vapor barrier has zero perm. When a slab is already in place we use Radon seal for water, radon, eveything protection. No vapor of any kind gets thru. Then, after that with an existing slab we would put 2" of continuous closed cell foam as a thermal break and double layers of 1/2" plywood in opposite directions top of that. This assembly looses 3"
Are the walls not insulated on the outside? If they are, is the inside insulation needed or is it just giving you 'extra'? Wish my slab was done like this (or done in any competent way..). For our daylight basemetn foundation walls i used Insofast panels as we weren't going to spray foam and didn't want to use the space to foam panels and stud wall.
Been wondering if this same slab detail could be used with no concrete and the 2 layers of Advantek instead. And instead of Type 9 EPS, to use something like Rockwool comfortboard 80 or 110. Although that EPS is probably going to be the most cost effective.
our hydronic system rests on top of 3 inches of yellow closed cell foam board. Pex is stabled to the foam board. Perimeter foundation has 3 inches yellow foam board insulating 3 feet below grade. Our slab floats within the perimeter of the foundation walls. Has not cost us over $600 per heating season so far.
I am. Screw all the extra work in insulation. Run the floor foam on top Stone and on top of the footers budding up next to the ICF foam walls then pour the slab. Now it’s all thermo broken.
So what if you already have the slab down and want to insulate the floor? I did xps on the walls and framed on that. Next is batting and astic covering....but the floors?
Now, a few years ago a contractor friend of mine was telling me a horror story about a family that had foam insulation sprayed in their attic - very similar to this - the family kept getting sick and it was determined that the outgassing of the foam was making them sick. Do any new products address this issue?
Keep these northern climate videos coming! I love what you do, but I have been dying for some videos that pertain to the "other half" of the country. I think you will really expand your audience.
For those older homes with slabs and cinder block foundation walls, and an old but apparently functional interior (French) drain to a sump (all working… except during hurricane and freak rain storms, a bit of ground water penetrates between slab and wall plus efflorescence on some areas) what is the recommended way to make them watertight and then insulate? Assuming you have done all you can do to get water away from the foundation on the outside. Also assuming, some of the walls have been painted by previous owners with *terrible* waterproofing paint that failed after about a decade.
Alaska requires special foundation insulation detailing so you don't melt your permafrost subgrade. Everywhere else, the basement slab is a nice cool element in the summer and should only need insulation when close to an exterior face (at 2 ft from an exterior face the soil itself will give you an R-value of 12 to 24).
I insulated my basement floor with 1" of XPS foam, 5/8" OSB on top secured with concrete screws. Works well and much, much cheaper than those insulated basement floor tiles. Losing an inch and 5/8 headroom is not that big of a deal.
Love your channel, been watching for years! Our 1956 Minnesota rambler has 12" block and we will be insulating the walls with closed cell just like this. We had to install drain tile and a sump system around the entire foundation and the foam will act as a vapor and air barrier for radon and moist. However, I would never insulate under the slab in this climate since the "cold" floor is 50 to 70 degrees WARMER than the winter air outside. Makes it easier to heat the house in the winter and cool in the summer.
My only thought here is that there needs to be some planning for how much vertical space that slab system takes up. If you really want your 8 or 9 foot ceiling then you'd have to account for (conservatively) the 20-22 inches of space used up by a system like that. Really solid and good, but make sure the rest of the foundation is poured low enough to account for this loss of space.
Two question , CAn I insulate my cold cellar ? It’s under the open porch here in Toronto Canada If so , how ? What is the best option for not to have mold issue in future ? Right now suffering from condesation on cold cellar ceiling & concrete top part which is above the ground
Foam is nothing but problems with pests. These builders build the house and walk away. They do t see the aftermath of their work. Foam is designed to be air tight. But carpenter ants, termites, squirrels, and mice love foam. Make holes in it; guess what? Its not air tight any more. Now there will be problems that can lead to major problems. Foam sucks and sooner or later it will be not used anymore due to these issues
Great video. What's the purpose of the square opening in the basement floor? And why is there a gap between the foam and the rock. Shouldn't the foam be resting on the gravel?
Can you spray that green foam over concrete blocks that have had moisture in them in the basement. I have one side which needs to be graded. But instead of digging on the outside of house for a watertight seal can this technique be done on inside?
Scott Moore , Warning urethane foam being applied against moist surfaces means uncared urethane and the odor is forever with a high potential of making people sick.
Good building practice in Finland is to insulate the basement from the outside. We don't have many basements nowadays because it's cheaper to insulate the perimeter of the house with EPS or XPS rather than to build the basement below the frost line. Also post WW2 basements had inadequate drainage so there were a lot of issues with flooding so basements have bad reputation.
What if you cannot insulate a cold celler from outside? Any possibility to insulate from inside without risks of mould or moisture?
@@vickzin If I had to insulate from the inside I would leave a vented gap between the wall and insulation.
this.
plus...
doing a building with eps around the peremiter now. it's like -10*C for a month now... was sprayed -5*C.
no heating what so ever, and it's been a constant 5*C inside.
i imagine if it was underslab insulation, none of that free geo thermal heat would come through and it would be -10*C inside right now.
I'm building a new house now. We just finished the foundation. My wife's uncle is doing the site work and he's pushing hard for me to insulate under the slab before we pour in 2 weeks. I've been fighting against it thinking its a waste of a few thousand dollars. This video has me re-thinking my position.
Always worth insulating
I know you're from down south but I'm loving these segments about building strategies in the Northern climates, they really apply to me.
same here...
me too, minimum code is R-10 for basements here, and they've already beat it!
Ditto. So helpful!
From what i have seen and heard it is best to not have the foam directly to the concrete. They make a special drain mat you are supposed to attach to the wall behind the foam to allow the concrete to breath. The same style drain mat is attached to the outside of the foundation to direct moisture to the drain tile at the footings.
That "interior weeping tile" solution is designed for basement walls that still have some water leakage from outside. In such situations it is better to permanently fix the water infiltration problem on the outside of the wall. When you can't dig up the outside on a cost effective basis, e.g. due to a shared driveway with a nearby neighbor, then the interior weeping system can be used with a connection to a sump pump pit.
@@paulsp6371 I have done a lot of remodeling on houses that have open cell and closed-cell they have been holding water and rotting box plates sill plates top plates and is a climate for post beetles and termites what's on paper is one thing what's going on in the field is completely 100% true Owens Corning opening letterhead stated they will not get involved with spray Foams because they feel that it's the next asbestos material and we don't have enough technology to understand it at this point
@@gaylehiner9511 I could not find that letter. Do you have a link? I have seen another video where the foam needed to be removed/replaced due to poor application and serious air quality issues. Risky when you see some of the people that are installing this stuff. Not all are quality people.
@@gaylehiner9511 The next "asbestos" is already here it is called "fiberglass"
Owens Corning makes foamboard...
German Architect/Construction Engineer/Prefab Construction Contractor here. Your videos are very informative about the US construction scene. But surely we wouldn’t ever do, what u guys are praising here. I advice anybody to check out the Eurocode Building Code on theese issues (available in Eng!). They are mostly created by German universities and Institutes, so they are pretty sound.
For example interior insulation is something, everybody try’s to avoid for good reasons. U have literally no active Thermal mass and u will always have a dependency on artificial ventilation/dehydration methods, since there will always be a humidity problem as well. Also nobody is using oil based Foaminsulations in the interiors, for health reasons (except for slabs without possible connection to the air). IF u realy need to have a interior insulation, you always go here for a mineral based insulation like foamglass, which can be plastered with lime-cement plaster (natural desinfection of the wallsurface) and is beeing able to „breath“ humidity in‘n‘out to a certain degree.
But if u build new, always try to avoid this stuff by using perimeter insulation on the outside of the basement, incl. a drainage plate and geotextile against the refill.
I’m a spray foam contractor in Canada and we usually spray foam on top of the grave with closed cell foam it acts as the vapour barrier as well as the insulating factor. The big benefit of spray foaming rather than using insulation board is if there’s any voids it fills them in rather than spanning over
But can't it get into the gravel and stop the movement of any water.
@@robertgregory2618 I would think it would only makes its way into the gravel by an inch or two before it sets up.
I can't imagine that you would ever recoup the additional cost in energy savings over board insulation.
@@zzzzzzzzzzzzzzzz8635 think about it your right.the company's get the spray foam in large quantities at a discount then stiff the customers because they can.
What happens when the foam starts to degrade????? I don't get it, a foundation should last 150 years at least, that foam is good for 15-20 years... then what. Your foundation will either be floating and weak or completely collapsed... no?
About to start work on a basement remodel in mixed humid climate. 50s house no slab insulation. Laying down deltaFL taped air tight - 3/4 iso foam - cement board. Steel studs 1” from wall, 2” closed cell up over band joist. Watching this - sounds like we’re pretty close.
Matt and Steve, thank you.
Any exterior foundation wall installation?
keep in mind, a closed cell insulation, below grade, on an exterior wall is illegal in the Midwest which is why it is also illegal to use a vapor barrier or in some cases, not even faced insulation under those circumstances. The moisture needs to be able to evaporate vs. being trapped.
Rob Fischer I noticed that they mentioned NOTHING about moisture barriers in this video...
Yep, that wall has 2 sides, and there is no way to guarantee that they can keep moisture out of the concrete wall, thus it has to be able to dry to the inside.
I wondered about this...check some of the articles Building Science Corp and Fine Homebuilding about why this works. According to Joe Lstibirek, PhD, 3.5” of closed cell still has enough vapor transmission to allow it to dry to the inside. Anything over that could be an issue.
Why is moisture in a concrete wall a bad thing? do you think it is going to rot?
@@Shad0wC0mpany2 That's because I believe in airtightness, water management, and surface temps of condensing surfaces - with that vapor doesn't scare me at all
Steve seems to be a humble and very knowledgeable architect, thanks for sharing!
Extremely lol!!!
I've never built anything more complicated than a dresser, no idea why I watch this but I enjoy it so much!
What about off-gassing? Long term air quality studies?
I suspect that's in God's hands. ;-)
Many homes in New England have issues with radon. It's easily solved with a mitigation system that could have been installed in the basement and home walls before this project was wrapped up. it's basically just a vent tube with an air pump.
@@chrishuyler3580 Thanks. Good info
Save so many hours of extra labour and material if you use ICF walls!
I'm confused about the closed cell on the basement walls. In the floor you have EPS then poly then the slab. Why not have EPS and poly on the outside of the walls to decouple the foundation walls from the earth outside, insulate the walls, and keep the moisture barrier on the outside of the walls instead of the inside. Aside from the thermal issues, it seems that hydraulic pressure from moisture coming through the foundation walls is eventually going to push the closed cell away from the walls, and pool water between the walls and the foam. Looks like the right idea in the floor, but backwards in the walls.
Patrick It's a terrible construction, but the US can't build concrete housings. Look how it's done in Germany, they know how to build massive. Never use sprayed PU foam on the inside. It contains harmful substances. Keep the concrete on the inside, it will hold the temperature and moisture constant for good room climate.
I agree you have to keep the moisture out. With that design the concrete walls will be constantly damp.
My guess is the outside foundation walls were also waterproofed. The issue with eps on outside is in cool climates the earth expands and contracts and eventually will destroy the foam. This is why it is now required in many areas to have a 6 mil Poly between earth and eps to act as a slip but this never works in reality. The technique they are using is a very good and cost effective solution if building this way. I only build with icf which solves all these issues with ease
@@paulnovak833 How is the foam exterior of an ICF block any more resistant to those foam-destroying forces than sheetfoam or sprayfoam applied to a block or form-poured basement wall?
@James Bloom icf block isn't going to move, nor would spray foam fornthat matter
Biggest mistake I made in my new house was not insulating under the slab! The tile floors in the bathrooms are uncomfortable in the winter due to cold radiating through the slab. Floor temps get down in the low 60's which makes the heat have to run more often. Great video!
Thank you sir, I agree, if only the knuckleheads above would listen to reason...
@@stevenbaczekarchitect9431 LOL!
I'm into Monolithic Domes and there the concrete is exposed on the inside. Why? Because of 3" of polyurethane insulation on the outside.
It's like eating a Goose Down jacket to keep you warm... No, you put the insulation on the OUTSIDE.
dig out the perimeter of the slab, and slap some EPS boards around it. it'll do a good enough job, because soil is insulative and a thermal mass. you have infinite insulation on the bottom; it all escapes SIDE WAYS.
the further down you run the eps boards, the more insulative it will be. varies a bit of course. say your soil is sand; sand has a r value of 7 per foot.
run the EPS 4 feet in the ground, and the heat will have to go through R28 on the way down, and then another R28 on the way up to leak out to the surface.
It's wild how Steve seems like he's not going to do well on camera until he starts talking and then is just awesome.
Its the sign of a guy who's in his environment, and knows his shit.
@@justinclark216right on. He is a professional
Matt you jsut get it man. Love your info and tutorials. Im a DYI'er and your info helps tremendously. .
Great video!! I have designed basement slab insulation systems and never stopped to consider WHY we put the poly on top of the EPS. Makes total sense! Just say no to "iceberging"!
So poly on top of insulation and not underneath?
Is this how code wants it?
@@rotaxrider in my area (central canada) I have never seen a code showing specific order... I typically do poly on top for this exact reason... Building inspectors never question it.. they just want to see proof of foam thickness if the plans called for a specific thickness..
Was the exterior basement wall insulated? That seems to me like the place to start.
Tell me about the cross section of 2x material under the floor joists above. Where I live, most contractors insulate between the floor joists and drywall directly to the floor joists above (uusing blocking to stabilize the floor joists.). What is the benefit of the 2x lumber attached and running perpendicular to the floor joists I see in most of your videos? I live in NE Pennsylvania.
This was great, good to see more about cold climates and more about basements.
my slab currently is sitting between 72 and 75, i'm mid remodel and so some portions of my concrete walls are exposed on the inside that are above ground outside on the side that gets afternoon sun, here in the middle of the night that section of concrete is just shy of 79 and I can say for sure that concrete is not insulated on either side. current outside temps around 70, yesterdays high was 90-93 and ground temp for my area is around high 70's at 8 inch deep
How do you know where the moisture is condensing in between the closed-cell foam and the foundation wall? Seems like trapping moisture in there might cause degradation of the foundation wall over time.
Always seal the outside of your concrete walls from water penetrating down to drainage system and sleve drainage piping from sediment buildup.
@@Eger7law011 Doesn't answer the question
Curious if you wanted a cold cellar in the basement would you do this or would you not do the section of the cold cellar?
The poly is also required for radon underslab control.
Mass Code requires piping installed under slab
Matt, love the videos. Q: Is there a separate radon barrier that turns down at footing in addition to that 10 mil turning up the wall? Or does the CCF keep the gasses from infiltrating the basement?
Just a few comments from living north of 50 degrees latitude: (I'm not really an expert, so please feel free to disagree.) Bat insulation doesn't perform as well in basements as above ground, because the difference in temperature at the top and bottom of the foundation causes vertical air movement within the bat. In the dozen or so basements I've torn up, there are always some spots that have been continuously wet, even with proper vapour barrier & moisture seals, drainage, etc. Any kind of hollow wall construction in an exterior basement wall in a bathroom will cause problems. I prefer to attach foam board insulation directly to the foundation wall and drywall to the foam for these. I've only seen sub-slab insulation when there is in-floor heating, with the exception of one house about five hours north of Toronto that had full-height south windows that heated the slab in the winter.
This guy Steve, along with you Matt are absolute Geniuses when it comes to building super efficient, strong and safe homes ! I live in Ct and used to do insulation from the age of 18-27, and what a huge difference from then to now. This technique is beyond interesting and valuable and the way this house is being done should be a benchmark for all builders, thanks for showing and if you have anymore videos of this place, please show them. Thank you.
I worked making fresh salsa for several years. We ran our production line at sixty degrees and operated out of an old freezer warehouse. We chose the building exactly for that reason. The floor and related substructures were probably a little over four feet thick. Concrete, foam and stone, then another series of concrete, foam and stone. Pretty impressive construction.
Awesome educational material, here given by two guys who are "national treasures" in my opinion. So no disrespect intended by my following comments. I am deeply grateful for EVERYTHING you do, and publish, so the rest of us can WATCH and LEARN. Especially, thank you for the warning of the "iceberg" moment that will wreak havoc if layering of building materials is mindlessly wrong! Meanwhile:
1) There is no mention of how deeply placed, below grade, this basement lies.
2) There is no quantification of the hydrostatic pressure exerted upon anything.
3) Is this on hilly, or flat, terrain? I've seen another of Steve+Matt videos, shot in Texas, where the surrounding land was shown, while a huge ground-water remediation project was poured. Egad that was awesome and mindboggling, to see that such countermeasures even exist. So many people (here in SoCal) just ignore geological issues. Not to mention all the SF-Bay people who live atop a powder keg... the San Andreas Fault.
4) I love the 10 inches of gravel, and the mention of French drains etc., in other words, this is a comprehensive solution; but:
5) If that gravel ever gets silted up, by any means over the next century or two, then really nasty things are gonna happen; so
6) Anyone who believes in, or uses, dry-well-type methods of sub-foundation water removal must contemplate the importance of all those air gaps between the gravel pieces. The gravel might hold up the building, but it's those air gaps that fill with water and allow an underground river to flow.
Thank you for considering my comments.
sot he house if fucked?
Insulation outside the slab is best, as the thermal mass remains inside the home. It’s why my 3600sqft brick Victorian only need 4 tons of in SE Iowa cooling despite tons of windows and no insulation. It just changes temperature too slowly. Most AC runtime is shifted to nighttime as the brick remains warms for hours. In the hottest part of the day the brick is still warming up.
From up north, too bad more builders don't insulate properly. Why not insulate on the outside of the basement concrete walls? Provides a thermal block and keeps the basement and main level floors way warmer...
Also, imagine all the extra SPACE you get to have! [1:30 > super space hog]
That’s where my 2” rigid insulation is on my basement!
I assume it is. Under the slab is insulated, so why wouldn't the walls be? This is just a mega house
What do you insulate the outside basement walls with?
Yeah its the vest way, but cost more. People just see the price tag unfortunately
I'm planning to (owner) build a home in northern NH next year and want to achieve a very high efficiency level. All these videos are going to serve me well. Very much appreciated.
Great!!
Daniel, tread lightly. Demand MSDS sheets on all foams you consider. Most off gas, killing anyone inside during a fire. Many breaks down from the elements and time, eventually turning to dust. Some shrink as much as 36%. Others detach when sprayed on concrete. In short, if any of these problems concern you, it's best you get it in writing. If they can't show you an "aging test" or off-gassing test or shrinkage test or loss of R-value test, then assume they can't pass one.
@@larrymaloney877 Thank you for that tip, that makes complete sense. I'm guessing that extreme temperature changes like we have, would only worsen those issues. I'm also very suspicious of the tapes being used to seal exterior sheathing/foam. Unless it's chemically bonding with the substrate, I don't see how that could last a century or more.
You can insulate after. Insulating pumped screeds are available now. I wouldn't bother personally though. It's much better to pour concrete on grade than foam that will creeep.
Why not just use ICF for your Foundation Walls? Thermal Breaks/ Wall studs all in one.
Christopher, my thoughts exactly..
In the white north I don't know why would anyone build basement out of anything else but ICF... beats me.. O hold a second, I think I know.. TIME.. :) :)
Everyone is builder these days and quality doesn't matter anymore.. Just this past January I saw a builder doing following:
Day 1. - temp outside = -25 deg. C - dig a hole for basement
Day 2. - 4 - temp outside= -25 deg. C - forming company doing forms
Day 5 - temp outside = -25 deg. C - cistern and pump on site pumping concrete
Day 6 - temp outside = -25 deg. C - forms are off
by the way, no heating whatsoever was done... Now that concrete doesn't have even 10% of bearing capacity and then people are surprised that basements crack. That concrete froze the minute it hit those cold forms.
I'm in the process of building my own house and it's ICF all the way to the roof. I'm not saying that everyone has to do that but for sake of insulation/thermal breaks, stable foundation etc. etc. use ICF...
Building in Ontario these days is a big joke and consumers have no idea, they just keep buying..
cost is the biggest factor, cheaper and easier to just spray the wall later. also tighter this way since the spray foam wraps into the floor band
That's what I did, (use ICFs) 18 years ago. I also used form-a-drain to pour the footings, and french drained the footings, inside and out. In western Washington we have very little radon, but that would also drain away any radon, as radon is 7x as heavy as air. The idea of insulating the slab is, at best, controversial, as the slab is a heat sink. If the heat can't escape sideways, it will just come back up into your house. My foundation walls are 4' deep, as I am in a wet location. With insulation 4' foundation walls, sideways movement of heat very unlikely.
BenjaminFranklin99 You built a good system, best is to insulate below slab because heat always goes to cold, i.e.. interior temps 68 f and grade 4' down 60-58f thus constant drain of heat to grade. The biggest factor is wet soils providing better conductivity to concrete and greater losses.
@ Yes that is the exact same system i use as well. The difference between regular forms and ICF and form a drain is that ICF can be done by anybody. In my personal home I had such a hard time with local ordinances that i just raised a 2x4 wall all the way around my basement. My spray foam guy went ahead and foamed it with rest of house so my basement is super insulated. I would never do it any other way.
My personal notes:
1: can rebar Concrete foundation walls be poured with the below grade rebar basement foundation slab as a monolithic pour to prevent air gaps?
2: for my 2x8 wall frame beams, I must learn from this video by distancing them a few inches from the concrete wall so I can pour closed cell foam exact same way as is taught to me here in this video.
3: Why does he say the walls aren’t structural? Are the concrete walls the only structural component?
4: Steve also like me thinks it’s a good idea to have a hydro break aka he pours 10 inches of leveled stone with a perimeter drain running around the foundation so that water never is in constant contact with the foundation like most houses.
5: Above the stone but under the concrete he has 4 inches of a special Type 9 EPS styrofoam that is rated for at least 25 PSI so it won’t break when the concrete above it is poured.
Thank you for insulating houses and basements and putting unfaced insulation in and covering with plastic it will keep my business going forever due to all the mold build-up you builders keep doing her and I'll just keep making my millions thanks
Yup...i always groan when I see that in a home. So common.
This basement will not grow mold!!!
Being a remodel of a basement, the closed cell foam makes sense. However, if this was new construction why wouldn't the goal be to apply the insulation to the exterior prior to backfill? This complements the use of insulation under the slab. I plan to use a rockwool product because it also deters termites and does not degrade in the presence of moisture.
Question... is the hole left open to serve an an access hatch to the drainage bed below the insulation and floor slab?
Tub trap
Also see the Insuladd interior paint additive. A guy using it inside a boat told me about it, to take up less space for existing construction. It is made from ceramic beads, a byproduct from burning coal.
How are the horizontal poly seams sealed together below the concrete slab or are they just overlapping?
Excellent! Love to see these details and hear the the discussion of why and how it integrates into the system. 👍
i would suggest that you watch the whole video. baczek discussed the details and how it integrates into the building envelope system in the video.
I did watch the whole video
Getting some tricks for your property additions?
Thanks David! Hope you are well sir. Enjoy your IG feed and RUclips channel! Your travels are my daydreams of retirement someday. Best, Matt
Absolutely!
I'm just doing my basement walls. spray foam was going to be about $7000.00. I put R28 batt insulation in for $1200.00. I did get the rim joists sprayed for $1700.00 so it cost me $2900 instead of $8700. The house walls are R24 and the ceilings are R55. We have triple pane windows too. I put rigid foam under the concrete floor which has heating pipes in it. It would have been good to sprayfoam but $5800 will buy a bunch of heat. Sometimes you have to do what you can afford.
I’ve got 2-3 feet of stone with tile in it , Polly and 6” of concrete on top . My coal stove is in the basement and yes it takes a day or two to heat everything up but one the concrete is warm everything evens out . In the summertime you put a box fan on the floor and it blows across that concrete - your gonna freeze ! Blankets in August !
This concept is awesome, making that basement air tight. Out west here in Colorado and SD we have issues with Radon Gas, I would think this would negate the need for a radon gas removal system saving a ton of bucks.
Radon (and radon mitigation systems) is pretty common in Boston area. I'm sure the building the foundation this way is more expensive than radon mitigation. And radon seeping through the concrete so it would need to be installed anyway.
I have an older home with cinder block walls that have seepage. I don't think this would be advised for someone in my situation. I had to break concrete and run internal drain tile and drill weep holes at the bottom of the block.
Cinder on grade or below?
@@konjiki240sx below grade.
1:30 - holy cow.... what is the costing for this room; and, is it ever going to be "worth" the money put into it...?
When its new construction it is less expensive to do these projects. Also, when your electricity bill for a 2000sqft house in New England is less than $200 in the winter it will be well worth it.
How much is it worth to have the room downstairs in your basement not cold if you actually want use it.
I know from experience it is a real drag to have it cold. I did the math with some quotes and it would never "pay" to insulate the room from savings but it would make the room pleasurable to use versus having it virtually unusable. Of course in the summer that room is the best in the house, always nice and cool.
interesting twist on closed vs open is if you have a cinder block foundation you should think about open cell. it will potentially allow the moisture to move which could save the block and mortar from deteriorating (assuming a retro fit old block foundation which may not be well sealed on the outside.
The slab looks like it's floating. It appears as if there is a small (one or two inch) gap between the gravel and the foam layer, with the concrete poured right on top of the foam. How is this? Or is it that the is foam resting right on top of the gravel and the gravel has been moved away slightly from underneath the foam in the cutout you used to show the layers? I can't figure out why it appears this way, and if there is any significance at all.
How do you insulate the slab when you are using Superior Wall prefab basement walls?
Matt, Can you comment on the concerns on off gassing of closed cell foam and is there anything that can be done to reduce this concern
I love the budgets Steve has to work with, my clients don't have the $'s for these luxuries also the loss of space would be problem for many referring to the shots of the double framed. I do love all he does, I just wish my customers had the money.
Todd, it is always a challenge to get clients to see the value. Most of them are not knowledgable. It is our job to make them see the light, and I know this, they ALWAYS have the money
Steve... they don’t always have the money. Not unless they are building custom with a finance of $850,000 CAD or more. To add all that extra care & work would be about $20,000 where I live (on a large home).
On a large addition say 18’x40’ it would be about half that just to start. Basically building costs about $100-250/sq. ft.
And that $100/square is for traditional framing meeting code with cheap Home Depot cupboards.
I live in Southern Minnesota and think about foundations and slabs a lot. This video's slab insulation process looks more complicated than it needs to be, at least from my thinking. I've been thinking about a good six inches of sand that is leveled and compacted on top of packed earth. I would then lay down one inch of dense foam and pour my slab on top of that. It's just something I've been thinking about and I'm not sure it's a good idea. What about painting the outside of the poured walls with roofing tar and glue on one inch dense foam board before back-filling with gravel and sand, finished with clay and top soil.
007vsMagua the roofing tar will eat the foam. The sand will hold water and not have big enough gaps of air to dry under slab which is important.
Question on under slab insulation! Where there is a column that is carrying load to a footing, is foam usually capable of carrying through that load from the column to the footing? Appreciate all that you guys do!
Any columns go directly to a footing - structure before energy
In older New England houses with a rubble or stone foundation rather than poured concrete, spraying foam isn’t recommended. Is there another solution?
Hey Matt, can you address any questions or issues people may have with their insulated slab cracking? Apparently many people doing this are having problems with their slab cracking all over. Any info would be great. Thanks.
The concrete cures too fast from the surface and shrinks faster than on the bottom. The plastic underneath the slab slows down the curing, since the water can evaporate only upwards from the concrete. Cover the surface with a tarp to slow down the curing.
The most common concern I had when I was in redi-mix was concrete being placed too wet. Contractors were known to ask for more water added on the job. While it makes it easier to work in the moment, the loss of cured strength and shrinkage cracks are high prices to pay. The above comment about the poly seal below requiring all of the moisture to migrate upwards bears true. Keeping the surface of concrete damp as it cures is never a bad idea.
@@jamesharder5643 so it would prob be prudent to wet cure a slab that is poured over foam and plastic?
This is one of the best videos I have seen on basement insulation. Is a sump required with this setup or would it be redundant? How would a French drain be applicable?
Why is there a gap between the gravel and foam?
From what I could gather was to make sure moisture never came in contact. That gap provides an escape for any water through the gravel before it can reach the foam or slab. Not an expert and only speculating.
So the entire 4” slab is floating in the air lol?
@@landonlandon5533 So, you also don't know.
Wow, that's some nice Detail! ...but curious about the foam Between the concrete layer? 2" slab, foam, 2" additional slab?
How flammable is that insulation? Is pulling the studs off the wall a fire blocking issue?
No the vertical height of a cavity is limited to 12'
Do you put the EPS on the footing as well or do you terminate it before the footing?
2" of the 4" rides atop the footing
In the South, would it be better to not insulate on the inside of the foundation wall to keep the thermal mass of the concrete wall within the conditioned space?
I'm wondering which town outside of Boston. I build in central Mass and in the basement I need a fire break every 10ft to pass inspection. Usually either PT or Roxul. Also we usually have r18 minimum so would need another r3-4 not by choice. And sometimes when using closed cell we get forced to use 5/8 sheetrock or 1/2 blueboard and plaster also for fire. Thanks for visiting the area! 😊
This was down on the Cape, feel free to contact me thru my website if you'd like to chat more. I'm actually from Western MA
Matt, I don't have a basement, and I'm sure as heck not a construction expert, but these are just so informative that I can't help but watch you ONnn the BUILD SHOW :D
Check out above Matt at end of video the closed cell insulation is pulling/shrinking away from stud. This would be a major air leak. An issue I always think of where spray foam is applied and soon after gyproc covers the wall and there is over time the shrinking insulation that is allowing the air to enter building. Should a vapor barrier (plastic sealed wrap) be installed and tape sealed as an assurance against this type of incident?
Fascinating !
Did I get this right??
8-10" rock
A french drain around the floor edge
4" foam//25 psi rated
10mm moisture barrier
4" concrete pour
How deep is the basement?? 10-12'?
What about plumbing/sewer?
Thanks Matt !!
Very well done, I know with the stone, insulation and vapor barrier being under slab there is little chance of capillary wicking of water from slab/footer. My question is since you run the spray foam insulation up into the M joist do you fully cover the M joist or leave some exposed to the inside so that in case any water wicks up in can diffuse though the m joint into the basement so the m joist doesn't rot/mold?
I was wondering the same thing. If the M joist is fully sealed inside, but not insulated and sealed on the exterior, it will wick moisture and not dry during the northern fall-winter-spring.
Dries to the outside
is that gravel under the entire slab or just at the perimeter?
1:30. Some shelving to recover the lost space would be great.
Hey Matt, is there any chance you can do a retrofit video for us northern homeowners who want to insulate our basement floors? I think I'm going to end up doing r5 over some seam sealed dimple mat, then a plywood subfloor over that. It should be enough to stop vapor and condensation without losing too much height in a basement without high ceilings.
mikecampanella1990 - I’m an insulation contractor in Cleveland, OH and your approach is one that we recommend and use with excellent results. Don’t know if you’ve seen the articles about this on buildingscience.com but it is well documented. Go for it, good luck with your project.
@@torstenhansen4308 great man! Thanks for chiming in! I'm glad it's a successful option because it's really all that I can do with my current home without spending entirely too much money.
@@nc3826 the only problem is that the house was made already and in 1951. Lol. So, my only option besides digging the entire yard up would be putting foam on the interior. With everything having closed cell foam on it and a full vapor seal, water shouldn't be an issue unless there was a burst water pipe down there and everything is brand new pex, in an insulated space. So, I don't see that happening. Any insulation I use in the actual stud walls will be roxul due to its no mold and fire proofing for against the foam.
@@nc3826 well, I had asked about a retrofit for the house because it's a 1951 and I'm not tearing out the slab and I'm not insulating it from the exterior. I will be putting down a dmx subfloor with 100 percent seal, then foam. The plywood will be tongue and groove and most likely floating, anchored at all wall bottom plates so no shifting will happen. I did not use pex a because I didn't have an extra fee hundred dollars for the machine. All of my own joist are accessible and ran with a manifold. I'm not worried about them at all.
I was wondering the same. I used 2in xps directly onto the concrete walls then framed over that. I was also going to insulate in the studs after running my electric, but the floor is tricky. I found some vinyl flooring that is completely water proof and goes down like a pergo floor. Just curious what i could possibly do for the floor....
interesting idea that the spray foam in the walls. But how do you deal with any moisture that's coming through the cement walls? It wouldn'thow evaporate travel down to the floor? We've always been taught to make sure that there's an air barrier between the cement and the insulation specifically for this purpose and it seems like we're totally defeating that by using closed cell foam. Is this a complete Paradigm change?
@Joe Bears yes and if you don't have an exterior one and can't add one, you should put an dimpled mat on the inside wall and an interior french drain. Water management must be done correctly before putting any insulation.
If you use a peel and stick membrane or any membrane for that matter on the interior side of the wall, it won't work. The water will push the membrane from the wall instead of pushing it toward the wall like when you put it on the outside. With enough time and hydrostatic pressure, it will unglue the membrane from the wall and you'll be back to square one.
Well the correct way to do it is to have membrane and drain, AND insulation on the outside of the basement wall. Yes in the dirt. That is how we do it in Scandinavia. But the slab thing is 100% correct and how we do it here.
@@72strand Some people do it this way in Canada too but internal insulation works as well. Plus, it blocks the footing from being a thermal bridge .
You just have to be really careful to not allow your warm air to reach the cold concrete wall and hope that your concrete won't crack after many cycle of freeze and thaw.
Actually, I think the better solution it's to put insulation on both side.
@Joe Bears the only way is too put foam under your footings. Some people do it in Canada but I would be worried about deflection personally. I would prefer to add some interior insulation instead or to not have a basement at all and have a shallow frost protected foundation instead.
I suggest ICF for the walls for that exact reason.. totally agree with slab.. I actually put mat underneath foam but my foam has locking edges to prevent concrete coming underneath...
What is the fire rating for the foam? In a foam insulated home, more folks die from deadly foam gassing during a fire than smoke or flames. Again, what is the published fire rating? Also, does that particular foam have a published test showing how it ages?
On a personal note, I had a fire in my home recently, and fortunately, came home just as it started burning from a shorted extension cord in my dining room. I had one piece of 2'x2'x1" rigid foam board in the dining room along with two sticks of foam trim, all against the wall. (The product that simulated wood baseboard trim.) The fire was still small so I drew buckets of water from the bathtub to put the fire out. That bathroom is just across the hall from the fire but I had to step outside and BREATH, before re-entering because of all the gassing from that little bit of foam. A houseful of foam would be deadly in an instant! Even my little fire was terrifying. I can't imagine being in a foam home & having a fire. I was lucky to come home and catch it in time. There was little damage from the fire, just my carpet, and sooty walls. But the gasses almost killed my kitty and me.
Again, what is the fire rating? Some products claim "will not burn." And truly, the foam doesn't burn. But it melts and off-gasses deadly fumes. What is the brand of foam? And please share brand's fire rating? It's been tested by a third-party testing organization. Where is their report? Please don't be shy!
Even fireblocking foam will eventually fail in the heat, so anyone who says "will not burn" is definitely spouting stuff that's misleading at best and an all-out lie at worst
You used buckets of water to put out an electrical fire? Forget the gasses, you're lucky you didn't electrocute yourself...
@@Regolith86 , good point, Rego...electricity and water don't mix. My fire was a carpet fire, caused by an electrical short in an extension cord. When I walked in the front door, the house was full of dark smoke. I couldn't even see the flames so I worked the light switch and the power was off. The short had finally tripped the circuit breakers so no electrical current could flow. Besides, I unplugged the defective cord. Again, the only issues were the fires burning is several spots on my carpet and the fumes from the melting burning plastic. I tend to get windy when writing but did my honest best to keep this one short. I hope these details rest your mind. I even used an IR camera to find a hotspot inside the wall. But when I drilled into it I found a was a kitty on the basement ceiling girder below. The camera was showing her body heat not more fire. It was a valuable lesson. I won't ever use trim boards made of foam again. It shouldn't even be available..too hazardous. And I'll finally get around to adding a few wall receptacles to accommodate the new service I installed...no more extension cords.
Several years ago I upgraded my electrical service to 200 amps. At that time I relocated the outside masthead and while installing the new meter I added an outside circuit breaker. I have a healthy respect for electricity. I once taught electrical safety as part of an electrical course I taught to electricians, maintenance personnel, and electrical engineers. My next personal upgrade will be replacing the conventional circuit breakers in my panel with the latest electronic versions. Some detect flash, arc, and leakage.
I remember when some wall to wall carpet products were pulled off the market, performing like Napalm in a fire before some insurance company flagged it. That was last century. Polysiocyanurate is the "go to" insulating product now, due to it's high (R 6.6) insulating value and it's ready availability and inexpensiveness.
But it off gasses over decades (70 years?) to where it eventually has a low R value. So what is the design life of a building? In my book, they should last hundreds of years, so polysio-based products are out. The only substitute I know of is compressed rock wool. Being organic, it never changes and being compressed, it can be applied in some places where fiberglass can't, like onto concrete and I think, under footings. R 4 per inch means you need 33% more of it.
But now we have a crisis; If we re-build all the houses in America properly, not using polysiso products (they are also a petroleum by-product), we have no chance of enough beneficial effect to help with the onslaught of Global Warming. If we use them, we contribute to Global Warming but will at least have some shelters that can weather whats coming. Obviously, we'll do what we have to so Polyiso products will be used predominantly. But the rest of the house is concrete and the design life of other parts is hundreds of years, so why add critical insulation that will fail after 70 years? Stick frame house yes, concrete houses, no way.
Food for thought, we'll all be in tents before the end of the next century anyway.
@@refusoagaino6824 , With your prodding, I remember the foam carpet that poisoned the homeowners who used it. Foam itself was removed from the market in 70's because of formaldehyde. Today, it's still found in small amounts. But when we mention "foam" it has several meanings because there are so many different kinds. The weak foams, like pump foam, rides on the coattails of the better foams pretending to have similar qualities. Trusting homeowners, who want to believe they are doing the right thing, pay double for an inferior product. They don't see the shrinkage going on inside. High-pressure salesmen have to lie in order to keep the product on the market.
Global warming isn't the consequences of poor insulating practices in the USA. IT's the direct result of gluttonous consumption of energy. Besides, there are very adequate, and affordable techniques and materials to retrofit existing homes with excellent insulation. It's just not foam. So don't use global warming as an excuse to burn more petroleum. We have the technology but the profit in foam drives marketing which is contrary to what planet earth needs. Politicians are about creating/maintaining jobs, not doing the socially right thing.
You could also spray foam the concrete walls and the top of the gravel all in one go. Should be more impermeable and air tight. 10" of gravel is pretty nice. I've seen lots of people only use 6". I guess it depends how much sand or clay is in the soil.
steve knows his shit. thanks Matt
Lots of good ideas here. We vary somewhat from what's done here. Poly isn't used because it has permeability. Stego or Husky as vapor barrier has zero perm. When a slab is already in place we use Radon seal for water, radon, eveything protection. No vapor of any kind gets thru. Then, after that with an existing slab we would put 2" of continuous closed cell foam as a thermal break and double layers of 1/2" plywood in opposite directions top of that. This assembly looses 3"
Radon is rare. I wouldn't get too worked up over it. I guess from a marketing standpoint it's handy though.
Steve at the end made this my favorite episode!!!
Thank you!!!
Are the walls not insulated on the outside? If they are, is the inside insulation needed or is it just giving you 'extra'?
Wish my slab was done like this (or done in any competent way..). For our daylight basemetn foundation walls i used Insofast panels as we weren't going to spray foam and didn't want to use the space to foam panels and stud wall.
Been wondering if this same slab detail could be used with no concrete and the 2 layers of Advantek instead. And instead of Type 9 EPS, to use something like Rockwool comfortboard 80 or 110. Although that EPS is probably going to be the most cost effective.
Of course have done that detail a number of times
Is there any way we could get a wall view drawing of that basement slab?
our hydronic system rests on top of 3 inches of yellow closed cell foam board. Pex is stabled to the foam board. Perimeter foundation has 3 inches yellow foam board insulating 3 feet below grade. Our slab floats within the perimeter of the foundation walls. Has not cost us over $600 per heating season so far.
If doing new construction why not ICF?
I am. Screw all the extra work in insulation. Run the floor foam on top Stone and on top of the footers budding up next to the ICF foam walls then pour the slab. Now it’s all thermo broken.
So what if you already have the slab down and want to insulate the floor? I did xps on the walls and framed on that. Next is batting and astic covering....but the floors?
38tech , Call InSoFast and glue down to slab, then install subfloor and finish floor. Fast dyi.
One of the best builders.. homeowners lucky to have you on the project
Now, a few years ago a contractor friend of mine was telling me a horror story about a family that had foam insulation sprayed in their attic - very similar to this - the family kept getting sick and it was determined that the outgassing of the foam was making them sick.
Do any new products address this issue?
The outgassing is only an issue if the chemicals aren't mixed properly.
Just wondering what the blue/green foam was in the slab?
Keep these northern climate videos coming! I love what you do, but I have been dying for some videos that pertain to the "other half" of the country. I think you will really expand your audience.
Can a concrete slab also be poured on extruded polystyrene?
For those older homes with slabs and cinder block foundation walls, and an old but apparently functional interior (French) drain to a sump (all working… except during hurricane and freak rain storms, a bit of ground water penetrates between slab and wall plus efflorescence on some areas) what is the recommended way to make them watertight and then insulate? Assuming you have done all you can do to get water away from the foundation on the outside. Also assuming, some of the walls have been painted by previous owners with *terrible* waterproofing paint that failed after about a decade.
Matt, great video. Do you have a video on water sealing basement walls? Thanks!
Alaska requires special foundation insulation detailing so you don't melt your permafrost subgrade. Everywhere else, the basement slab is a nice cool element in the summer and should only need insulation when close to an exterior face (at 2 ft from an exterior face the soil itself will give you an R-value of 12 to 24).
Did they seal the outside of the foundation?
I insulated my basement floor with 1" of XPS foam, 5/8" OSB on top secured with concrete screws. Works well and much, much cheaper than those insulated basement floor tiles. Losing an inch and 5/8 headroom is not that big of a deal.
Yup..and XPS is a nice vapor barrier!
Love your channel, been watching for years! Our 1956 Minnesota rambler has 12" block and we will be insulating the walls with closed cell just like this. We had to install drain tile and a sump system around the entire foundation and the foam will act as a vapor and air barrier for radon and moist. However, I would never insulate under the slab in this climate since the "cold" floor is 50 to 70 degrees WARMER than the winter air outside. Makes it easier to heat the house in the winter and cool in the summer.
Consider insulating OUTside the foundation, That thermal mass can make a much more temp stable living space.
@@joe4324 Excavation is too costly.
To answer a question from below, the hole is either for a sump pump or a radon vent pipe. (sump pump to pump out excess water if needed)
My only thought here is that there needs to be some planning for how much vertical space that slab system takes up. If you really want your 8 or 9 foot ceiling then you'd have to account for (conservatively) the 20-22 inches of space used up by a system like that. Really solid and good, but make sure the rest of the foundation is poured low enough to account for this loss of space.
How about one of those existing slabs?? Have a method? Thanks!! Great videos!!
Two question ,
CAn I insulate my cold cellar ? It’s under the open porch here in Toronto Canada
If so , how ? What is the best option for not to have mold issue in future ? Right now suffering from condesation on cold cellar ceiling & concrete top part which is above the ground
If you cover the mudsill and rim joist with spray foam do you not get problems with termites? Isn't it supposed to be exposed for inspections.
Foam is nothing but problems with pests. These builders build the house and walk away. They do t see the aftermath of their work. Foam is designed to be air tight. But carpenter ants, termites, squirrels, and mice love foam. Make holes in it; guess what? Its not air tight any more. Now there will be problems that can lead to major problems. Foam sucks and sooner or later it will be not used anymore due to these issues
Where this project is located, termites aren't really a problem
Great video. What's the purpose of the square opening in the basement floor? And why is there a gap between the foam and the rock. Shouldn't the foam be resting on the gravel?
Maybe a sump pump? Also, it probably is, it just doesn't look like it here.
Can you spray that green foam over concrete blocks that have had moisture in them in the basement. I have one side which needs to be graded. But instead of digging on the outside of house for a watertight seal can this technique be done on inside?
Scott Moore , Warning urethane foam being applied against moist surfaces means uncared urethane and the odor is forever with a high potential of making people sick.