Cracked plaster walls


Old 12-23-04, 09:50 AM
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Cracked plaster walls

I'm planning on taking down cracked old plaster and putting up drywall. My question is what thickness should I go with. I would like to remove the old wood lathes and put at least 5/8 drywall. Another option would probably put up 1/2 (or 3/8) inch over the wood lathes. Tell me what you guys think. Also what R value should I insulate with? 1 wall is shared with a bathroom and another wall is an exterior wall, the rest interior walls. My last question and most difficult is the ceiling plaster is in perfect condition should I take it down and drywall it anyway or leave as is? Any and all comments appreciated.
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Old 12-24-04, 12:16 AM
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Keeping the ceiling depends on whether you are satisfied with the texture pattern, lighting, ect. If you what to add lighting, venting, and/or significantly change the texture pattern, you will likely want to take it out.

The main differences between sheetrock thicknessess have to do with fire control, sound dampening, and insulating quality. Obviously, 5/8" will do all of these things better.

Depending on the type of insulation you plan to use, and the R-value you want, you may need to remove the lathe. In situations where sheetrock is installed over lathe, and there is no existing insulation, blown-in insulation is generally used to fill in behind the lathe. Also, many people like to insulate interior walls that abut bathrooms for privacy and plumbing noise control.

There are a few things that you may want to think about: what caused the walls to crack in the first place? You should know the answer to this before you proceed, since the factors causing the initial problem may still exist - for example, is there a shifting foundation problem? Is there poor moisture control on exterior walls? This is important if you plan to leave the lathe in place on the exterior walls.

Best wishes and Merry Christmas!
Old 12-24-04, 01:50 PM
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Thanks for the reply. Lots to consider but at least I'm moving forward. Thanks for the post.

Have a Merry Christmas!
Old 12-24-04, 02:47 PM
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Hello & welcome to the forums.

rdn2113 has pretty well got you on the right track. I would just throw out my opinion, the odds are that the studs in your wall will not all be true & plumb, back when house were built with plaster & wood lath, it really wasn't all that important, because the plasterman took care of this with the plaster. So in order to get an acceptable finish product with the new drywall you will most likely have to shim some of the studs and you may actuallly have to shave one or two of them down a bit to get a true smooth wall. Because of this I would recommend doing away with the lath along with the plaster.

As to the ceiling, good luck removing the wall plaster w/o damaging the ceiling, best way is to cut thru the plaster all the way to the lath about an inch or so below the corner with the ceiling and then carefully by hand removing the narrow strip right next to the corner. If you just start ripping plaster off the wall without doing this first, chances are you will end up damaging the ceiling plaster even if you don't mean to. An if you happen to have blown-in insulation in the attic above this area, alot of it will end up in the floor. Walls are generally hung with 1/2" drywall, like was previously stated 5/8" is better, but if you're planning on insulating the wall cavity, it would be a bit of overkill IMO.

Here's a link to the DOE's insulation facts page, you will find good info located here for proper inulation values for your specific region.

Good luck with your project & Merry Christmas! :glocke:
Old 12-24-04, 07:41 PM
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cracked plaster walls

I have a related problem - just moved into a house where the stairs to the basement have a landing and 90-degree turn and the landing was noticeably slanting. Looking from the basement, it was clear why - one corner of the landing was just hanging out in space, unsupported...since 1934 it would seem. A friend helped to hammer some 2x4 support beams underneath and we managed to raise the landing about 1 1/2" to almost level.
Only thing, the plaster wall above the landing cracked big time. After cleaning out the obviously cracked area, approximately 2 ft. x 2 ft., it became clear that much of the rest of the plaster along that wall was no longer well attached to the lath underneath.
Long way of getting around to asking - is there some way of re-adhering the plaster that remains before repairing the large hole (plaster board insert and topcoat or Structolite base coat and topcoat? recommendations?) or should I take all the remaining plaster off along that wall and install plaster board rather than plaster to repair. Reading the previous response, should I then take all the lath off as well?
Old 12-25-04, 06:54 PM
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Quote: "My question is what thickness should I go with."

As mentioned, 1/2" minimum - but 5/8" is better. But there are a couple of things to consider before deciding.

'awesomedell' has pretty much explained what you may run into when gutting walls - relative to the studding. As he said, some of those old-time framers didn't go crazy plumbing the studs. And if the studs were slightly bowed, that didn't seem to bother them either. Again - as awesomedell explained, they relied on the plasterers to flatten the walls, and they (the plasterers) did so quite effectively. This is evident when you tear down the plaster. You'll find some sections thicker than others.

Because I own income property, I've remodeled a number of homes. Sometimes a complete gutting - room by room by room. I always remove the lathing, because for one thing I use rolled insulation, and another reason is because upgrading the electrical is relatively easy because the walls are completely exposed. This is the time to add outlets, fixtures, etc. And another is when shimming or planing studs, you obviously can't do it with lathing in the way.

By the way, when shimming I use the fairly common method of running strings across each wall. Sometimes shim here or there will be enough. Other times I've attached vertical wooden strips against the studs from top to bottom and shimmed in back of that. My only point here is that you don't always know what you're in for until the walls are gutted. This goes for the ceiling as well. Remember that you're shimming in order to make the studding in the same plane. The drywall will follow the studding so if the studs are out of plane, your walls can end up noticeably wavy.

I happen to be finishing up a 'sun room' right now. Only 10'x14' with 7 windows. 2 on one side, 3 in front, and 2 adjoining an open porch. Lots of woodwork. Now the problem: this room needed lots of "fill" because take away the lathing plus very thick plaster, and wanting the final wall to meet up evenly with the window and french door jambs, it made it particularly challenging to match because they all differed. My solution was to shim the studding to 'flatten' them out, hang 2 layers of 1/2" - which brought me close to the window jambs. (Note: another method could be to rip the jambs, but since all 7 were replacement windows already installed, it was an option I didn't care to take because it would have meant taking them out and then reinstalling them.)

Anyway, the 1" drywall came out perfect on the wall with the french doors. No problem. The other three walls were different. If the casings were attached to the jambs as is, there would have been a space between the outside casing and the walls. A space as much as 1/4". This is AFTER regaining an inch with the drywall. Anyway, the solution was relatively simple. I put my adjustable dado on my table saw and trimmed the 1/4" off the backside so the casing met both the window jamb and the wall. The head casings were stopped just short of the ends - so as not to be seen. If all of this sounds scary, believe me it's a lot easier to do than it sounds. Further, you may not need to do the above. I'm offering it only as a "just in case."

Like yours, this ceiling was in good shape (unlike the walls). The plaster was tight to the lathing and the lathing was tight to the ceiling joists. But to get it to conform to the new walls, I simply skim coated it. Looks as good as new.

Also - the way awesomedell described removing the wall plaster where it meets the ceiling is exactly how I do/did it. And when hanging the drywall, you jam it snug to the ceiling. I use the paper covered metal corner strips for a very crisp look - as well as for strength.

And one final tip. When hanging dual layers of drywall, I screw the first layer to the studs as usual. However, I don't fuss with it 'cause there's no need to. When hanging the second layer, I use either construction adhesive or drywall compound. Either one will lock the layers together and will nearly eliminate any need for screws. (Never had a wall fall - yet. )


Last edited by Aarno; 12-25-04 at 07:09 PM.
Old 12-29-04, 04:20 PM
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Question cracked plaster walls

My house was built in 1940 and has plaster walls and ceilings on wood lath. there are full length cracks in the ceilings. Prior owner tried to patch with drywall mesh tape. I went over that with drywall mud. Now the mesh tape is coming lose and separating from the plaster. What can I do to patch the cracks?

Also, I have heard there is a bonding substance that can be applied to cover the crack and then add new layer of plaster or mud. True?

Last edited by bzrnole; 12-29-04 at 04:22 PM. Reason: add question
Old 12-30-04, 07:36 AM
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Megann-- there is no way to get that plaster to stay up. Rip it out and re do with drywall.
Old 01-16-05, 04:55 PM
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cracked plaster walls and ceiling

Help folks! I have cracks in the plaster and hoped to get on the repair tomorrow. But, I have not heard from the experts. What do I do? Thanks

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