Sheetrock repair isn’t too difficult. Essentially sheetrock is chalk that’s compressed between two paper surfaces. When one of the paper surfaces is torn, the chalk shows through. Simply painting over it all isn’t a good solution. You need to do more to create a good looking repair.
It's worth remembering that although sheetrock is used so widely, in many ways it's not that strong and in damp conditions can crumble quite easily.
Step 1 - Cleaning
If there are sections of paper hanging loose, you need to cut them away carefully with a utility knife. With large pieces that don’t look stable, cut around them and then gently pull the paper away to expose the chalk beneath.
Step 2 - Joint Compound
Take some of the joint compound and spread it lightly all over the area with the drywall knife. Be sure it’s only a thin coat, so you’re not raising the level too much. Try to keep it flush with the rest of the wall wherever possible. After it’s dried completely, sand it down smooth with the wall and check to be certain you’ve covered all the exposed chalk.
Step 3-Large Area
If the problem covers a large area, you need to not only use joint compound, you also need to cover all this with drywall tape. This will keep it in place. Again, it will need to be covered in joint compound and sanded.
Step 4 - Second Coat
Now, apply a second thin coat of joint compound. Again, try to make it as flat as possible, but this time cover a slightly larger area, so you’re feathering into regions where the paper covering is good. Give it ample time to dry before sanding smooth and then taking off all the dust with a clean cloth.
Step 5 - Sealing Primer
With the joint compound dry and smooth, apply a thin coat of sealing primer on top of all the area covered by the compound. A single coat should work well. Give it time to dry. In this sheetrock repair, most of time is taken up by waiting for areas to dry, rather than in the actual work. Once dry, inspect the work to ensure everything is properly primed and smooth.
Step 6 - Paint
To finish the sheetrock repair, paint the area of the wall that’s been affected. Make sure that you have a color that matches completely. If you don’t, you’ll need to repaint the entire wall (and possibly the whole room).
Start on the affected area and work outward. Use a thin coat of paint and feather it into the existing color on the wall to give a good blend. Give the paint time to dry and then apply a second thin coat of paint. Once again, work it in lightly to the existing paint so you can’t see a difference between the two areas. Let it dry, and then apply a final coat of paint only if it’s needed.