How To Repair Plaster Walls and Ceilings
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- Опубликовано: 19 окт 2024
- Learning how to repair plaster walls and ceilings isn't as hard as you think. But it isn't like drywall and uses very different techniques and materials.
Materials needed:
Don't use straight plaster of Paris. It will set up before you can get it out of the bucket. Use Durabond 90 instead. It's a plaster of Paris based product with premixed retardant. It will give you around an hour of working time. Use general purpose sand for your 1st and 2nd layers. Metal lath and plaster bonder are the two other things you'll need.
Plaster construction has two parts, the foundation called lath, and the plaster that is spread through it and on top of it.
Lath nowadays is metal screen-like material but earlier construction is thin strips of wood. In both cases the lath is fastened to the ceiling joists or wall studs. When repairing or restoring a plaster surface it's important that the lath is secure and sound.
Plaster can be gypsum or lime based or even a mix of the two. Lime plaster is the oldest type, made by burning limestone in a kiln. The resulting lime is used for plastering and for cement. Gypsum plaster, known as plaster of Paris is also made by heating in a kiln.
Lime plaster is the superior choice especially for kitchens and baths but it's much harder to work with. For general interior work gypsum based materials are a better choice for amateurs.
Plastering is usually done in 2 or 3 coats. You can spread the coats out over a few days or even do them all on the same day. The existing plaster and lath needs to be slightly damp. Each coat of new plaster should be misted with a squirt bottle before the next coat is applied as well.
The first coat, called the scratch coat, is a mixture of sand and plaster. In older homes it often had horse hair or other fibres to help it stick to the lath. Applying the scratch coat is tricky. The plaster is more or less squeezed through the holes or gaps in the lath. Lots of it can end up on the floor or on your head.
The second coat goes on much easier as most of the holes and gaps in the lath will already be filled in. This coat is a mix of sand and plaster as well. This coat should sit a bit below the final surface to leave room for the finish coat.
The finish coat is straight plaster. It should be fairly thin, perhaps a ¼ inch or so. Before laying this coat it's a good idea to scrape down any areas of existing plaster that have sand stuck to them. You can see me do this with the edge of my float in the video several times. Doing this will keep sand out of the finish coat. Hopefully you can get a nice smooth surface with your trowel on your first attempt. Doing so will save you a lot of very difficult sanding once everything is hard and dry.
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This is the best instructional video I’ve watched on repair my old plaster walls thank you
Thank you so much for your kind words!
What a great informative video. Thank you!
Glad you've found it useful!
Andrew Shackleton does what nobody else on RUclips DIY video does -- that I have seen -- with regard to plaster ceiling repair: he shows you a tough job. I noticed that the other DIY videos all have plaster "bubbles" or sections of ceiling that bowed out and need to be pried away and repaired/filled in with drywall. The repair is relatively easy. There are not three coats of plaster and related products. There is one coat of "mud." He also follows up with all of the comments made here. Nice work from Andrew.
I'm glad to come across this video. I just had some rewiring done and needed to patch some plaster wall and ceiling holes this video was very helpful.
I'm glad I could help you a bit. I wish I'd got footage of all three plaster layers going on. No doubt I will end up doing another repair at some point.
@@AndrewShackleton this morning I brought some metal lathe, brass screws ( for rust prevention). I brought a Dremel oscillator tool and a grout removal bit which is great for neatly removing plaster without damaging the lathe underneath so I could expose some wood lathe to screw the metal lathe on. Once again thanks.
Excellent thanks for making this video
Glad you liked it!
That works. There’s also a product USG makes called structo-lite that’s designed as a modern day base coat for plaster so u don’t have to mix and sand. Can finish over it with any material u design or use a float to finish with it
Thanks Oskar! I used structo-lite on another room 15 years ago. It does work good.
@@AndrewShackleton Whats the difference between you adding sand then just using concrete for plaster? Nice video BTW.
@@falsealarmno you could use cement and I have done so on the outside of my shower. Old school bathroom and kitchen plaster has a high percentage of lime putty (calcium hydroxide) to help deal with moisture. Modern cement is chemically quite different but older non hydraulic cement is mostly calcium hydroxide too. As I'd said in the video most inside plaster is gypsum (calcium sulfate) and it doesn't deal well with being wet. Sand or other lightweight aggregates are important for scratch coats for mechanical reasons. You are transitioning to a hard brittle finish coat to wood lath and then ultimately to the wall or ceiling structure of the home.
@@AndrewShackleton Oh! Ok. Thank U sir.
Thank you for the information! I have a similar repair. If the sides of the lathe are clear of plaster, do you recommend removing the insulation and pieces of plaster from the attic that are stuck above the lathe?
You shouldn't need to unless there are huge runs of plaster stuck in the gaps. Jsyn, the first coat had horse hair mixed in when being used with wood lath. You'll probably have a lot of waste with the mix I'm using. Not an issue, just something I'm pointing out.
Walls, Type S mortar with accelerant to speed setting. If have metal lathe it is easy. Ceilings? Originally it was generally mortar similar to modern TypeS. Waaaay cheaper than Durabond . 60 lbs sack is under $5. Around here, only Sika type R adhesive. Pressing it into the ceiling lathe is tough. I might try Durabond 20.
Thank you for the excellent suggestion. When I first tried finish plastering I was mixing up lime putty with plaster of Paris and it was going off too quick. I used structolite for my scratch and it was fine. More recently I've had great success with Durabond but a cheaper alternative is always good.
I’m getting ready to fix some holes in my house from a knob & tube removal and replacement job. Will I need to cut out more of the plaster to expose more lathe to attach the metal lathe to? Also, based on the comments would you still do your repair the same way or would you do a finish coat with easy sand or some of the premixed joint compound? Thank you for this video BTW. Super helpful.
You can fix the metal lath to any solid structure. Studs or joists or the wood lath. If attaching to wood lath just chip back some of the plaster to expose the wood. You can wire or staple the steel lath in place. I would use Durabond 90 for your repair as it's way stronger than regular drywall compound. If you've ever finished cement you'll see the cream come up on the plaster the same way. That is an opportunity to run a float over the surface and get it perfect.
Why didn’t you remove the plaster between the lathe? Isn’t the plaster supposed to get pushed up through the lathe and mushroom over the top side to give it holding strength?
Not sure you are I are looking at the same thing. The wood lath is 90% free of plaster. The metal stuff has none. The part of the video where I'm spreading plaster is the second coat. The first coat wash squished through the lath, trust me. Lots of it ends up on the floor too.
Drywall over the whole ceiling
Just saw this video. I have a home that’s about 95 years old so a lot of plaster in the house. Anyway, the back bedroom has two windows and the wall around it is roughly original plaster but I can see that roughly half the plaster is damaged or covered up with 1/4” Sheetrock. The sheetrock is mostly by the left window so the wall isn too even bc of this. Haha I ripped out the baseboard yesterday and the plaster above it is pretty mangled. A lot of it crumbled under the baseboard so I want to repair it. Would you nail in the metal lathe on top of the brick and then out cement on top of it? Would you then do a straight durabond mix and put it on top or mix durabond with sand like you did in the video? Any feedback would be highly appreciated.
Yes, your lath needs to be securely fastened. Not sure how you'd attach to brick though. You mentioned cement to fasten lath to brick? Maybe galvanized nails into the mortar joints instead? Scratch coats were made with sand and horse hair back in the day. If you don't want to muck around making your own scratch coat go buy structolite. I've used it, works great. Finish over that with durabond. If you aren't going really thick you can get away with a scratch coat and only a single finishing layer.
That doesn’t look like what plasterers use. I don’t think they’d use dura-bond. They use a product called structolite first, then they use plaster. But I’m curious if this held up.
How did it look once painted?
It's gypsum plaster or plaster of Paris. But it has a retardant in it. Regular plaster of Paris goes off in 10 minutes. Durabond 90 hardens like rock. Almost impossible to sand. Gypsum is the most common type of interior plaster. Bathrooms and kitchens are a mix of lime plaster and gypsum to deal with moisture. For the scratch coat I just mixed Durabond with sand. 2nd coat was a bit less sand, 3rd was just Durabond. Scratch coat in my house (1889) is horse hair and sand and gypsum. The structolite you mentioned is plaster of Paris and volcanic glass aggregate. My repair turned out just fine but there are trowel marks because I'm a complete amateur.
@@AndrewShackleton hey do you know if durabond 90 sands like 20 minute hot mud? I wasn’t trying to be critical of your work. Just wanted you to know that. I’ve been watching videos lately on plaster repairs and I was just curious how yours turned out using durabond.
@@wyattsdad8561 nothing wrong with asking questions. Sorry, I don't know what hot mud sands like. (apparently it is the same thing according to internet) Durabond hardens like cement. It is almost impossible to sand. It has a cream come up just like concrete. You need to be good with a float.
@@wyattsdad8561 20 min hot mud is durabond just sets faster than the 90 minute.both are considered hot muds and neither are really sandable per say. If you get the usg ez sand its a tad easier to sand once its completely cured but there is really no need to sand durabond you put it on and when mud sets you just lightly go over it with a knive or trowel to remove the high spots and fill in holes if necessary . the final coat should be with a sandable material like anything light weight plus 3 for example at home dep hope that helps
@@robre6840 I do a lot of drywall patching for work and I do sand durabond when I do a patch that involves knock down texture. I use 80 grit sand paper on a block. You cannot use a pole because it’s too difficult to apply enough pressure to sand durabond with a pole. It saves me a lot of time because I can complete the patch in one day. If I do smooth wall or imperfect smooth I use topping over the hot mud. I have done a few smooth wall patches using only twenty minute mud and I’ll sand it with 80 grit, then use 120. Usually only in an office building tho. It will then need to be painted with 3 coats of paint to hide the halo effect that appears because the durabond is slightly different in its look and feel. But if you apply three coats of paint it hides this pretty well. However I would not do this in a customers home,
I use topping for the final coat.
I don’t think you really need to use the sand for interior but I’m not expert. But I’d also use 20 and not 90. Stuff dries hard as a rock.
I used sand in the scratch coat to match the mechanical properties of the existing plaster scratch coat which has a lot of sand and horse hair in it. I think this lessens the possibility of cracking.
The big corporate companies are going to hate me after I make this comment but who cares, Never use durabond for interior walls that stuff doesn’t sand when dry and it cracks leaving hair lines on the outside edge when the house moves because it’s cementious and cement doesn’t contract and expand, if you use it at least use it for the correct application, if your making house repairs use plaster of Paris it has lime in it that withstands moisture and repairs itself when wet it sands unlike durabond but is harder than joint compound, if your using joint compound around showers or sinks don’t do it because the compound will bubble and blister it’s water soluble meaning anything that it comes in contact with that is wet or moist can dissolve it, plaster of Paris on the other hand is your best friend when it comes to interior repairs it’s the reason all the tall cathedrals in Europe are still standing after hundreds of years of weather changes.
Hi Santiago, Durabond is not cement, it's mostly Plaster of Paris with a retardant so it sets up slower. You're a bit off about the nature of Plaster of Paris. It contains no lime. It's made of gypsum, the mineral Calcium Sulphate. Lime is Calcium Hydroxide and water. This information is very easy to look up on the internet. If you are making interior plaster you will often mix lime putty and Plaster of Paris for damp areas such as kitchens and baths. I have used lime putty and Plaster of Paris to make interior plaster and it didn't set up well because I don't know what retardants professionals were using. Durabond gets around that problem nicely. Regular Plaster of Paris without a retardant sets up way too quick aside from very small jobs.
@@AndrewShackleton your confused plaster of Paris already comes with lime in it hence the reason it can suck up moisture and fix itself and is a retardant do your research before commenting I’ve worked with plaster of Paris for 25 years and have done months of research stop misleading trolling people
Sandals?
I'm barefoot around the house most of the time. I throw on sandals when I'm in the basement.
You people sure do things the hard way 🤨🤨
Would have liked to have seen from the very beginning layer to the last layer, not just everything in between. Still helpful. Thank you.
It would be Nice if you would show step by step in video
I want to redo this video next time I do a repair. Step by step for sure next time.