Uneven walls create a couple of important issues in your home or office. Aside from the most noticeable issue, which is that the wall may be noticeably uneven and unsightly, the other issue is that uneven walls can make it difficult to install wall coverings, like wallpaper or tile. If you have uneven walls that you would like to fix, the method you should use depends on the material from which the wall was built.
Find all of the uneven spots in the wall. One way to do this is to move a level across and down the wall, checking the wall for evenness every few inches. Mark dips in the wall with chalk or, if two full sides of the wall are uneven due to a bad drywall or plaster installation, mark the line down the wall where the unevenness begins.
Skim 1/2-inch layer of levelling compound over each dip in the wall or the uneven side of the wall using a putty knife. If you are filling in individual dips, drag the edge of the putty knife over each dip once you fill it to skim away the extra compound. Let the wall dry for 4 to 5 hours.
Sand the levelling compound with medium-grit sandpaper just until the wall feels rough and brush the dust away with a dry rag. Apply a second 1/2-inch layer of compound to the dips or low side of the wall. Allow to dry 4 to 5 hours.
Check the wall for levelness using the same process as before. If the wall is not yet level, continue adding layers to the wall, sanding the surface with medium-grit sandpaper before the application of each layer, until the wall sits level.
Sand all the filled areas of the wall with fine-grit sandpaper once the medium-grit sanding process is complete. Paint the filled areas to match the rest of the wall.
You can repair both drywall and plaster wall surfaces with levelling compound.