One of the most common of all household repairs is patching drywall. Whether you've moved a light fixture or someone's put a doorknob through the wall, closing up the resulting hole and blending it in with the rest of the wall probably seems pretty intimidating--but it's actually quite simple.
Only basic tools and materials are required, plus a little patience. Here's an old drywaller's repair trick that works great:
First, even up the edges of the hole with a drywall or keyhole saw so that it is round and all of the damaged material has been removed.
Next, cut a circle out of a piece of scrap drywall, 2 inches larger in diameter than the size of the hole. Turn the piece over, and mark out a circle on the back that is the same diameter as the hole. Use a razor knife to carefully cut through the backing paper along the edges of this smaller circle.
Crack the drywall along the circular cut by gently snapping it from back to front. Carefully peel the outer circle of gypsum off the front paper, and you will be left with a circular patch that has a one inch strip of paper all around it on the front.
Apply Second Layer
To make the repair, coat the inside edges of the hole with drywall joint compound. Using a 6-inch-wide drywall taping knife, apply a layer of joint compound to the wall around the hole also.
Push the patch into the hole, and use your taping knife to embed the paper strip in the joint compound. Smooth out the paper and remove any excess compound. Let the patch dry overnight.
When the patch is dry, apply a second layer of joint compound over it. This time, make sure the compound covers the entire patch, plus an area of the wall about 6 inches past it on all sides. A 12-inch-wide drywall blade will work best, but you can also do this with a 6-inch knife.
As you apply this second layer, try to "feather" the compound out onto the surrounding wall surface, so that the edges are fairly thin. Don't worry if there are ridges or slight irregularities in this layer, as they'll be sanded out later. Once again, allow the patch to dry overnight.
Sand the patch with 120-grit sandpaper, using either a drywall sanding pad or a 3-x-6-inch block of wood. What you're trying to achieve here is a smooth patch that tapers off onto the surrounding wall without obvious edges.
Sand carefully, so that you don't penetrate into the underlying paper. If you can't get a smooth, well-blended patch after two coats of joint compound, apply a third layer and feather it even farther out onto the surrounding wall. Let it dry and sand it smooth.
If the wall has a textured surface, you'll also need to match the texture in order to have the patch completely blend in. In older homes the texture may have been painted on, or hand applied with a trowel; newer homes typically have texturing that is blown onto the walls with an air-powered spray rig.
In either case, texturing your patch will require some patience and imagination. Begin by studying the existing texture, and try to determine how it might have been applied and how you can best duplicate it. Spray texture has the appearance of random globs when viewed closely, and can be matched by thinning joint compound with water, then flicking it onto the wall with the end of a paint brush or whisk broom.
You might also try applying regular joint compound with a trowel, a stiff brush, a sponge or some crumpled newspaper, or try thinned-down compound applied with a heavy paint roller. A little experimentation is all it takes for a perfect match.