Old houses are appealing on any number of levels. Some of us cherish the period detailing; others appreciate the refined proportions that older buildings can have. And some people are simply charmed by the sense of history that seems to float in every nook and cranny.
One of the most common characteristics shared by old houses is their pervasive use of plaster. It may not be in the best condition, but it certainly has more style than gypsum wallboard.
Fortunately, for those of us who own an old house, plaster is highly repairable. Cracks and holes can be filled, and plaster that has pulled away from the lath can be reattached.
Since refurbishing an old house is a messy and difficult business, repairing plaster instead of replacing it improves the efficiency of the process. Time and money that would have gone into replastering a wall or ceiling can be diverted to more pressing concerns, such as fixing a leaking roof or replacing aged kitchen cabinets.
Schedule your plaster repair so that work that can affect the finished plaster is done first. You don't want to fix a plaster ceiling only to have a roof leak ruin it.
Once a plaster surface is cleaned, repaired and painted, you'll notice a significant improvement in a room's appearance.
A plaster surface is composed of three or more coats of plaster secured to a lath. In turn, the lath is fastened to the house's framing. The lath may be wood, metal, paper, or strips of gypsum similar to drywall.
As the first coat of plaster is troweled on, it's pushed through the small spaces between the lath and oozes behind it. The plaster dries and is locked to the lath. The portion of the plaster that has dried behind and around the lath is called a key.
Usually, two or more coats of plaster follow the first coat. The three coats are quite heavy, and if the plaster keys behind the wall or ceiling surface break, the plaster sags away from the lath. Sagging plaster, especially on a ceiling, is a cause for some alarm. Vibration from above can break the keys completely and let the plaster fall in chunks.
Damaged plaster can be reinforced using drywall screws and plaster washers. Three saucer-shaped washers are punched from spring steel, and are perforated to hold patching plaster or drywall compound.
Screws (with plastic washers) are driven into the lath and framing surrounding the damaged plaster. The saucer-shaped washers nearly flatten out as the screw is driven home. Like a washer and bolt, a plaster washer pulls in on the surrounding surface as the screw head bears down on it. The cupped nature of a plaster washer makes the screw head easier to cover with a skim coat of drywall compound.