Q: I live in a condo in an old brick building in Cleveland, at the top level. The wood floors sag in the middle of the condo. It starts high on each end and slowly sags to a low spot towards the middle. It is a 3 b, 2 bath condo on the 4th floor (top floor). Old wood floors on top of a sagging frame.
What should I do to correct the wood floor sagging. Should I rip up the old wood floors, glue and screw sister floor joist to the old ones to reach level, put a new sub floor down then a new floor? Not sure what to do. The drop from highest elevation to lowest is about 2.5 inches over a span of about 30 feet.
A: You would have to remove the old flooring and sub floor to expose the joists. I think I would simply use strapping fastened to the top of the sagging joists. You would have to adjust the thickness of each piece and keep checking with your level. This would be a lot cheaper than sistering with new joists.
Follow-up Q: Can you explain strapping fastened to the top of the sagging joists?
A: I would use 1×2 or 2×2 depending what is needed. Use a level or plumb line across the floor to see on each joist how far off level it is and cut the strapping down to the appropriate height. You will need a table saw. You could likely make any fine adjustments with a belt sander and coarse abrasive or a planer.