ShareThisQ: We live in an older home -- say, built around 1905 -- that has the old horsehair plaster on the walls and ceiling. We would like to do over the ceilings and paint the walls.
Would it be best to just screw Sheetrock on the ceiling and then plaster? As far as the walls, how would you recommend to smooth the walls so we could paint?
Maybe it would be best to stick with wallpaper to cover all the patch marks.
A: Plastered walls and ceilings have been around for hundreds of years, and when properly maintained they should last another 100 years or more. The cracks and falling plaster are most likely caused by the expansion and contraction of the wood lath that supports the plaster.
Cracked and bulged walls can be an eyesore, but a loose-plastered ceiling is very dangerous. Plaster is very heavy and if it should fall on someone it could cause serious injuries.
A new covering of drywall should be attached with screws directly to the ceiling joists. Screws attached to the wood lath and not to a structural ceiling joist could fail to hold the drywall in place.
If the ceiling joists are 16 inches apart, then I would recommend applying a minimum of 1/2-inch-thick sheets of drywall to the ceiling. If ceiling joints are 24 inches apart, use 5/8-inch-thick sheets of drywall. Use screws, not nails, to fasten the drywall to the ceiling.
The screws must be long enough to penetrate the drywall and plaster and then extend at least 5/8 inch into the ceiling joists. There should be a minimum of one screw every 12 inches over the entire surface area of the drywall.
The home's walls can be skim coated using 1/4-inch-thick drywall, but you will lose some of the aesthetic appeal of the room's finish because the added drywall will cover a portion of the woodwork's exposed edges.
There are do-it-yourself remedies for severely cracked and damaged plastered walls. One product you can try is Plaster Magic.
You'll need plaster washers and screws from the hardware store, or you can use the washers and screws included in the Plaster Magic kit if there is wood lath supporting the plaster.
To make repairs, first drill several 3/8-inch holes through the plaster on all sides of the cracks. Try to drill in between the wood lath strips. If you drill into a piece of wood lath, stop drilling and mark the hole with a pencil for identification.
Later you will install a plaster washer and screw at the marked holes. The next step is to spray a conditioner into all of the unmarked holes.
Allow the conditioner to set for 10 minutes, and then apply the Plaster Magic adhesive through the unmarked holes until they are filled. Then secure the cracked plaster to the adhesive using plastic washers and screws.
Allow the adhesive to set for a day or two, then remove the screws and washers and fill the cracks with a spackling compound. For smaller cracks, simply secure the loose plaster using a plaster washer and screw found at most home stores. Once secured, the loose plaster can be finished with a spackling compound.
(Dwight Barnett is a certified master inspector with the American Society of Home Inspectors. Write to him with home improvement questions at C. Dwight Barnett, Evansville Courier & Press, P.O. Box 286, Evansville, Ind. 47702 or e-mail him at d.Barnett(at)insightbb.com.)
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