plaster walls and ceiling repair

17 years ago

I have a home with plaster walls and I believe ceilings too built in 1941. They are both in pretty good shape but we want to redecorate and before painting I thought we should address any problems. The ceiling has a hairline crack running the length of it and another closer to the side wall. There is no visible gap, just a crack but I wondered if painting over that would not cover it or probably only temporarily and if so how to repair? Also the walls have what looks like indentations(though it does not feel indented) all along it's length running horizontally every 18 inches or so. This is not apparent unless you look at the wall from the side and the light is hitting it. But I don't know if this is just the way plaster walls look or is this something that needs to be repaired? I am used to drywall which is very smooth. How would I make the walls and ceiling smooth if there is a problem with this look? Anybody famililar with this?

Comments (4)

homebound
17 years ago
I don't know what it's actually called, but it sounds like you have a 1940's version of wallboard which came in shorter, thicker pieces, almost like large tiles.

I'm widening a closet in our 1947 home, and I demo'd a wall partially. It's the same stuff you're talking about. It crumbles more, and seems more concrete-like, breaks sort of like concrete, too...(and creates a fine, concrete-like dust). These pieces are stacked upward on the wall and are nailed to the studs similar to drywall - but they're almost 3/4 thick.

Anyway, I think it's safe to say you can repair them as you would drywall. Perhaps taping and mudding the ceiling hairline crack. And putting a skim coat and sand the walls to get rid of those lines you're seeing.

Good luck.
brickeyee
17 years ago
REmove the switch pkate or a receptacel plate to try and see the edge of the wall.
One of the earliest uses of gysum board was as a backer for 2 coat plaster. The backer is tyopically 16 x 48 inches and 3.8 inch thick. A gray coat was then added and a white finish coat to bring the final thickness to 3/4 of an inch for the entire wall.
The shrinkage you are seeing sounds like the edges of teh backer board where the gray coat was not supported completely.
You can use Easysand to skim the depressions if you want a prefectly flat surface. It is easier with a plasterer's trowel and some practice.
Very fine cracks with no gap may be covered with paint, but if anything is moving with the humidity they can open again through the paint film. There are products that claim to bridge and allow painting, but I normally apply mesh tape and use setting joint compound to feather out the patch to about 12-16 inches wide.
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Lead pint is possible (lead paint was gloss paint). Asbestos is not nearly as likely in old plaster. You should be able to make a decent repair and just paint the ceiling. Setting type joint compounds (Durabond and Easysand) will make an excellent repair. What type of lathe is the plaster on? Wood and expanded metal both were used. If the lath was removed you can make a good repair using drywall as the base behind setting compound. If you get a good surface finish the repair will not show once painted.
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I would imagine you could repair the cracks and sand out some of the lumps, or at least skim coat over it if it really bothers you. It really depends on whether the plaster has become severely detached from the lath. And even if that has occurred, you can re-attach the loose areas with plaster washers. Don't expect 'perfect' surfaces in an old house, or you will be constantly disappointed. A couple of our ceilings have cracked, and in one room it is because the ceiling joists have sagged. You really need to spend a little more time examining the house before you can determine what has happened and how or if it can be fixed. As I've mentioned in previous posts, plaster can seem to be in pretty bad shape and still be salvageable, and it's worth the effort to do so, IMO.
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sfsuperstar: "My husband's really doesn't like the ridge, and the rest of the ceiling is so smooth he thinks trying to blend a 3/4" deep ridge will look obvious, so his tentative plan as of this evening is to remove the ridge of mesh to try to flatten it, then try to redo the crack repair smooth." That sounds reasonable. You may have to widen the crack just a bit more and clean it out, trying to cut under the edges as much as you can so the patching material has a place to grab in to and hang on. sfsuperstar: "It seems that the sagging part isn't an edge of the mesh, but is a center part of the mesh -- like an upside-down mini-mountain ridge. Should he try to cut out just the ridge part of the mesh with an exacto knife, or does he have to remove the whole mesh tape (even the part that's not sagging)?' I would guess it depends on how easily it cuts. I've not used it before, so I can't say. If it ravels and gets frayed and stringy, then it may be hard to cover over again with whatever you use. sfsuperstar: "And should he re-repair the crack / removal damage with flat drywall tape and joint compound? Or is there something plaster-specific that he should use? I'm not familiar with the patching plaster you mentioned." It may be OK to use the drywall tape, but I would wonder how much it would give or move under changes in temp and humidity in the ceiling without breaking loose at some point. I really don't know! We got the patching plaster at the hardware store; it's dry and comes in fairly small bags, and you just add it to a small amount of water in a container and let it absorb the water, stirring or 'folding' the mixture only very gently. If memory serves, drywall compound is still water soluble after it dries, while the patching plaster is a bit more impervious to water once it dries. Drywall compound also has a tendency to crack easily as it dries if it's applied to thickly, and the patching plaster doesn't do that as readily.
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I'd recommend you get a Do-It-Yourself book on drywall repair (your library may have a few). You'll be cutting some filler strips of drywall and securing them in the gaps. (I'd use drywall screws vice nails.) You may need to fashion some backing strips to fasten the fillers to. Ensuring the surfaces line up with each other and the filler strips can be tedious, especially in an older house, but it will be hard to disguise any misallignment. You'll then force some joint compound into the gaps between the filler strips and original surfaces, apply joint tape over those gaps and more joint compound over the tape. Sponging and sanding are used to finish the surface and feather the edges of the compound. Additional thin layers of compound wil help with imperfections. It's good to know when to walk away and let the joint compound dry before applying another layer rather than trying to work it to perfection in too few steps. Trial and error is necessary to develop your 'feel' and technique.
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cateyanne
Original Author
17 years ago
Thank you for the info. I am surprised that I do not have traditional plaster walls. Everybody said that is what they were and they do look like it. I did check behind a switch plate and the wall appears to be made of some kind of board, with a similarity to modern drywall but not quite, It is covered by a layer/layers of a plaster like coating and is in total about 3/4 of a inch thick. What is Easysand? I have not heard of this, can it be purchased at any home repair place like home depot or lowe's? You mentioned "products that claim to bridge and allow painting" for the ceiling cracks, what are these products, are you referring to a type of paint or patch? Thanks again.
brickeyee
17 years ago
You have 2 coat plaster instead fo 3 coat. # coat is over wood lath or expanded metal mesh. 2 coat is over a gypsum support. It is real plaster.
Easysand is a setting type joint compound. It is in the aisle with the drywall finishing mud in paper bags.
You mix with water to whatever consistency you want (like peanut butter is good) and apply it. The number in the EAsysand label is the working time in minutes. Easysand90 is pretty good for starting. You cannot slow the hardening by adding more water since it is a plaster product.
Peel Stop is one, there are others. They claim to provide a flexable membrane over the spider cracks and allow paint to stick and not chip off. Sometimes they work, sometimes they do not.

plaster walls and ceiling repair

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