Plaster and Drywall Repair

I had an elementary school friend, Paul, who came from what you'd call a relaxed-priority family. Until my first visit to his place I'd never been to a home with dead cars on the lawn, a screen door you had to kick open, and evidence of people having slept on the floor. But when I walked into the bedroom Paul shared with two older brothers my understanding of the range of life's possibilities expanded even further. That's when I discovered a gaping hole in the drywall about the size of a door knob. Paul casually explained it had been there forever, evidence of his oldest brother's temper. Didn't every house have door knob holes?

The fact that people could get passionate enough about opening doors to cause physical damage made the whole world look different to me in a strangely attractive, dark kind of way. Childhood can be such a rich time of cultural discovery, don't you think? Over our grade-school career together I went to Paul's place many times, always drawn to the eternal gaping hole for at least one look. My last inspection came just before the family's casually-disciplined St. Bernard broke its chain on a mission to ravage my leg. Once I'd discovered that the lingering fear of a dog attack is more compelling than a fascination with household destruction, I never went back, even after the stitches came out. For all I know the door knob hole's still there.

I'm glad Paul's Dad didn't know how easy it is to patch drywall. If he had, I might have been robbed of an important childhood memory and a handy introduction to a magazine story. But the fact is, fixing all kinds of damage to drywall and plaster is easy and satisfying. And without some kind of repair strategy, the inevitable dings and craters that develop in walls will get the better of you. When standards like these start to slip, dead cars and strangers sleeping on your livingroom floor aren't far away.

Door knob-sized holes should always be filled initially with a setting-type compound for the first coat. These come as powder that you mix with water into a paste that hardens in an hour or two by chemical reaction. The strongest formulations aren't sandable after they cure, so work neatly if you use them. There are sandable setting-type compounds but these aren't as strong and may not stand up to subsequent door-flinging passions. Regardless of what you use, you'll need to begin with some kind of solid backing to support the compound as it's applied. Otherwise, the compound will simply slump down or fall into the wall cavity before it sets.

The best backing stock is 1/4-inch or 1/2-inch thick plywood. Cut a piece slightly narrower than the hole in width, and 2 inches longer than it in length. Drive a wood screw part way into the middle of the plywood for a handle, then snake the ply into the hole, holding it tightly in place against the inner face of the drywall by pulling on the screw. Secure the plywood backing to the surrounding drywall with screws while holding it in place, then remove the screw handle. A 4-inch wide drywall knife is the best tool to use for spreading compound over a repair area this large.

Expect to apply at least two, and usually three coats of compound over a repair zone before it's fully covered. Coats beyond the first should be air-drying drywall compound or a sandable setting-type product. Mix these up with a drill before application for smoothest results. A 1 1/2-inch diameter spade bit makes a great mixing paddle for batches of mud too small to be stirred with a full-size paddle.

Professional drywall people usually leave sanding until after the last coat of mud is applied, but if you're new to the wall repair business, consider sanding after each coat has dried using a foam abrasive block. You'll get smoother results more easily this way. Finish up by feathering the edges of the patch zone for a flawless repair.