Repair & paint plaster


Old 01-29-03, 09:50 AM
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Repair & paint plaster

I am attempting to patch and paint VERY OLD plaster walls.
It seems to be going OK so far. Though I am running into a lot of holes and crumbling in one room, quite bad actually. How can I repair large areas? Would it be easiest to tear off the plaster and dry wall in these areas?
Also, I have found that some walls in another room are pretty well intact, and am wondering about painting techniques to keep the old worn plaster look to it, like you might find in an old farm house I suppose.
Thank you far any and all help!
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Old 01-29-03, 06:09 PM
Join Date: Nov 2001
Location: Taylors, SC
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I have had similar problems in my 1939 house. I just fill the holes with joint compound, sand, prime, and paint. I have had some areas, one 2x2 where the plaster was crumbling. I cleaned it out, getting all the loose material, and filled it with joint compound. You can use plaster, but I did not. To finish a large area and make it flat with the rest of the wall, I made a sanding board that was longer than the width of the patch to use to sand it. This covered the area and made sure that the repaired surface was flat and level with the surronding area.

I see many recommendations for removing the plaster and installing drywall. I would not want to have to deal with rebuilding the door and window casings and moving the baseboards and replacing some of the baseboards in order to accommodate the thinner drywall. My plaster walls are 1.25 inches thick. Drywall is generally 1/2 or 5/8 inches. Restructuring the wood work would be more trouble than it is worth.
Old 01-29-03, 08:44 PM
bungalow jeff
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You could always shim under drywall patches and then skim coat over the drywall surface to bring the level up and to feather out the patch.
Old 01-30-03, 08:35 AM
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Any patch will only be as solid as the base. If the plaster is old enough to be on wood lath and the keys (the places the plaster sticks out between the lath strips) are seperated from the base coat the best solution is to pull it off. Enlarge the opening untill you get to solid plaster. Build up the wall with layers of drywall held in place with settiing coumpound and screws untill you are about 1/8 below the finished wall surface. Fill the final 1/8 inch with a setting type joint compound. I have rarely encountered plaster on metal lath that has failed unless the lath pulled away from the structure. In that case run drywall screws in and fasten the plaster back to the structure, then skim coat with setting compound. If you are forced to strip an entire wall, sister the studs with a ripped 2x4 (about a 2x2) screwed to the side of the stud and protruding far enough to be even and at whatever drywall thickness you want to use. I try to use 1/2 inch fibrebond if I can. Instead of cardboard faces the fiber is inside the material. It is heavy and sounds like a plaster wall after installation. Two layers of 3/8 works also (3/4 is available, but is very heavy and hard to handle). If I wanted 1 1/4 instead of moving the stud face with sistering, I would stack up 1/2 and 2 layers of 3/8. Stay away from premixed drywall mud for patching plaster. It is not as hard as the plaster and in thick layers takes forever to dry and shrinks horribly, requiring more coats. Setting type compounds mixed with the minimum amount of water barely shrink. Easysand will sand, Durabond is much harder (and heavier). The 'patching plaster' is not worth a darn either. Plaster walls are made of a combination of gaging plaster and lime putty. Patching plaster sets up way to fast to be usefull. You can buy retarder, but it is rarely worth the trouble unless you are trying to do a real historic restoration, and then you should use the lime putty anyway. Use Easysand90 or 120. You can apply another layer when the first one is set. You do not have to wait for it to dry.
Old 01-31-03, 10:48 AM
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One thing not mentioned so far is that you should make sure the cause of the deterioration is addressed. Since the plaster is not crumbling in adjoining rooms, it sounds like localized moisture ... is or was there a roof leak? A plumbing leak? Sprinklers hitting the outside wall?

Make sure you deal with the underlying cause(s) of the deterioration before fixing the symptoms.

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