Sheetrock, or drywall as it's technically known, is the foundational backing for most interior walls in homes and other buildings. It's relatively inexpensive, not terribly difficult to hang and finish, and is easy to paint or decorate. The process of installing drywall involves hanging it and taping and mudding the joints, which is called finishing. Only after drywall is finished can it be textured and decorated in the appropriate manner, whether with primer and paint or wallpaper. It can happen, though, that existing drywall gets damaged somehow. Perhaps blunt force knocked a hole in the wall or water damaged a certain portion of it. When this happens, it's necessary to repair it.

Size and Scope of Repair
Fortunately, small areas of damage in drywall can be fixed without having to remove and replace whole sheets. Drywall that is rotting all over needs to be completely replaced, but for the most part, sections can be cut out and patched. The first thing to do before repairing it is to determine how extensive the damage is. If it's just a small section, a patch job won't take a long time, not counting the time it takes for the mud to dry.

Drywall Repair
After you know the extent of the damage, trace around it on the wall with a pencil. Locate the studs on either side of the damaged area and mark them on the wall. Making sure your lines are level and plumb, trace a square or rectangle from stud to stud on center, being careful to fully enclose the damaged portion of drywall. You will then cut along the line with a utility knife until the portion of drywall can be pried out, revealing the inside of the wall and studs.

Drywall Patch
Cut a new piece of drywall to the exact size as the hole and set it into place. You need studs on either end so you can securely attach it at both sides. Set drywall screws every 8 inches, affixing the patch piece to the wall. Now you have to apply all purpose drywall mud in each seam on all 4 sides. Adhere a length of drywall tape over the mud and run the drywall knife lengthwise over it to press it into the mixture. Remove the excess and let it dry. You will follow this with 2 more coats using successively bigger drywall knives each time to fan the mud out and conceal both the tape and the rise it creates in the wall. Once this is done, you can re-texture, primer and paint.

Smaller holes in the drywall can be fixed with what is called a "California patch." Take a scrap square of drywall and on its backside, trace out the approximate shape of the hole. Score around it with a utility knife, but don't push the knife through the front paper. Carefully break the gypsum around the scored area and remove the back paper. What you will be left with is the entire square of front paper and the gypsum core inside the area you traced. The rest will have fallen away. Fit the gypsum into the hole and smooth out. The front paper acts as the tape. All you have to do is mud over its edges to patch the wall.