plaster wall cracks? help!

[rshackleford]

i have lived in a 1925 home from seven years. the walls have always had a few lines in them, but no real cracks. my wife painted right after we moved in and it seemed to hide them all. this summer i had several layers of ceder shakes taken off and ashpalt shingles installed. at the same time i had a couple of roof vents installed and a bathroom fan installed. we were in the house when they were taking the shingles up on the roof and throwing them around. we felt the house bang and shake. we noticed a couple of new cracks right away.

this was six months ago. it is now January and we well into our second full month of record cold winter (10 to 20 below on a regular basis). we have started to notice a lot of cracks in the last six weeks. i feel like i am seeing cracks grow on a daily basis noe. they almost aren't craks though. a few of them are cracks, but most of them are little ridges that are raised to the touch.

what does everyone think is happening? what should i do?
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[Gary Swart]

What is happening is simple to answer. The house is expanding and contracting with the changes in temperature. It is normal and nothing you can do to stop it. What to do with the cracks is another problem. I don't think you will ever cover them all. Paint will seal over them for a short time, but eventually the contraction/expansion will reopen the cracks. I have had some success, not 100%, patching cracks using pieces of nylon stockings under the patching plaster. Use the nylon just like you would paper or mesh tape over a joint. Those little hairline cracks are going to be with you forever.

[rburt5]

I think I've heard of people widening out the cracks with a knife, applying silicone in the crack, and painting over it. The silicone is flexible enough to expand and contract. Anybody else heard of this? I don't want to give bad advice if it won't work.

[Gary Swart]

I assume that since this house was built in 1925 the walls are lath and plaster, not modern day drywall. I have not heard the silicone solution, but it sounds like a possibility. Won't hurt to try it.

[D.Smith]

Funny you should ask this question. TOH did a segment yesterday about plaster and lathe. They did a repair where the plaster had broke away from the lathe. There is a system out there that binds the plaster back to the lathe by drilling holes.


http://plastermagic.com/

[GabeS]

If the plaster is not attached good to the lathe, then you need to remove it or just go over it with drywall.

If it's attached good, but just cracking, then you could put wire mesh tape material(comes in sheets, not the tape) and the entire surface and a few coats of compound mixed with plaster.

Or you could use a bonding agent instead of the mesh material. It's called plaster weld. Once you paint it on the wall, you could apply the skim coating to the wall.

[rshackleford]

i might try to post some pics. maybe do it this evening.