Once your concrete is sealed, you'll move on to the framing portion of your basement re-do. If you want to make sure your room doesn't lean like a fun house, then a level is an absolute necessity. Levels are inexpensive and useful for many household projects, so it's not a bad idea to have a few different sizes. A 4-foot level is a good all-around level to keep on hand, and 6-foot levels are great for setting doors and rough framing. Smaller sizes like 1-foot or 2-foot levels are great for hanging artwork on your finished walls.