One of the trickiest parts of installing flooring yourself is getting the floor level before installation. The subfloor, the layer (usually made of plywood) that provides you a surface over the joists, might look flat to the untrained eye. But across the width of the room, the levels can grade just a fraction of an inch, and while it might not seem too bad, it can seriously affect your finished flooring.
Without a level subfloor, your hardwood or tile flooring can buckle and crack, damaging these expensive materials. Prevent this by taking the job of levelling your floors seriously!