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Hi Y’all,
I am repairing a 50-year-old residential ceiling that was damaged by moisture.
The ceiling is plaster over a sand scratch coat over concrete.
The scratch coat is sound, and most of the plaster, but I have had to peel off some chunks of failed plaster. These sections are on the lower end of the sloped ceiling and are about 6″ wide.
The plaster varies from 1/4″ to almost 1/2″ thick.
My question is, what do I replace the plaster with?
More plaster?
Can I just use several thin layers of drywall mud?
I read the recent posts and am still not sure exactly what to do here.
Brand names would be useful if there is junk I ought to avoid.
Thanks a bunch, Weogo Reed
Replies
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There's an excellent plaster site at http://www.ornamentalplaster.com
You'll find an answer to your question there.
*Frequent debate topic. Do you repair or replace with drywall. Purists say repair and do it the traditional way. Power tool freaks say rip it out and nail up drywall. Homeowners usually stuff a bunch of fiberglass tape over the area and use drywall mud.I have never had any luck with repairing plaster. Once it has cracked, and lost the key into the lathe, it is over. When introducing new plaster to the area, the two plasters have different ingredients, and expand and contract at different rates. Even with tape and mud, the area cracks again.I now pull the whole thing off, and slap some 1/2" drywall over the lathe. I leave the lathe on, and just apply over the lathe. If there is crown molding, that usually leaves you about 1/8" to slip the drywall between the lathe and the moldinng.No crown? consider using 5/8".I have seen many contractors who simply apply thin (1/4 or 1/2) drywall over the plaster, but it tends to get sorta wavey, and knowing where to nail is real iffy.Assuming you must repair, I use stucco mix for the base coat (California One Cote), and a good quality plaster with a lot of lime for the top coat (California Top Coat). Make sure you tape the joints well.
*Does this make you a power tool freak?I'm surprised you've had so little success with patches. Maybe i haven't been through enough seasonal changes. I belive fiberglass tape helps, though someone recently said you shouldn't use it ... but a crack is obviously a point of significant stress. If the plaster is separating from the joists/studs, of course, it's going to need to be screwed back before anything will work. (Our house has buttonboard, and the joints betwen panels are apt to crack.)Weogo, you might consider fastening some metal lath to the removed ssections, tying it physically to the old lath, and replastering the old-fashioned way. It depends on your patience, desires, and skill.Drywall ... yech.
*hi Y'all,Thanks for the comments and brand/product names.And especially the link to the restoration site, which will be useful for much of the other work I do.This ceiling is concrete with a tightly adhered sand(or is it called scratch?) coat. There is no wood or metal lath.It is only the last layer that is failing in small sections, 95% of it is sound.I'm no purist, but with most of the plaster in excellent shape, no way am I going to rip it all down and put up drywall! :-0Heck, I have avoided plaster for too many years, time to have some fun!Good health, Weogo