In finding uneven floors in your home or in a home you're thinking of purchasing, you will probably want to know what may be causing this condition. With this information you can better determine whether to expect more sagging and whether it might be possible to prevent it from worsening. Review the information below to help you determine what might be causing your uneven floors.
Check the degree of sagging by examining your floor. A floor that slopes from one side all the way to the other side indicates that a sagging foundation may have caused the sagging. To level your floor, in this case, you will need the help of a contractor.
A floor that is uneven in spots but does not have an even slope across the entire floor, is likely to be caused by bulging or loose plywood that has been used for your sub-flooring. You may need to rip up and replace existing plywood, or simply tack the existing plywood down more securely.
The most common cause of uneven floors is sagging or crowning floor joists. To remedy this problems you can either use a self-leveling product, or use shims between the joists and your plywood sub-flooring.