How to Correct a Floor Joist That Is Pushing the Floor Up?

If the floor issue sits near the walls or doors, take off the door frames and baseboards in the room. Use a putty knife to cut through the paint on the tops of the baseboards and at the tops and sides of the door frames and to pry the trim away from the walls. Use a pry bar to pull the frame and boards away from the wall if the putty knife doesn’t provide enough leverage.

Remove the walking floor in a manner that allows the flooring to be used again. Lift the outer edges of hardwood floorboards at the perimeter of the room until the boards cannot lift any further and use a hammer to pull the nails free from the other side of the floorboard where it meets the floor. With tile floors, use a chisel and hammer to break away the caulk holding the tiles together 1/4 inch at a time and pry the tile up slowly with a putty knife.

Use a tack cloth or wet mop to clean the floor underneath the walking floor, at least in the area where you need to make the repair. If you need to repair the floor near a wall or doorway, clean the floor all the way in from the walls and doorway to the area that needs repair.

Pull up the floorboards of the subfloor in the area with the joist issue by using a pry bar to get beneath the edges of the floorboards until they pull up slightly. Use a hammer to remove the nails once the boards loosen, and remove the boards the rest of the way.

Put a level down on the first joist causing the issue of the floor pushing up. Slide the level across the joist until the level finally shows that the joist sits evenly. Mark the end of the even section of the joist and the beginning of the sloped section.

Sand the sloped section of the joist with an orbital sander. Check the joist repeatedly with the level to determine when the joist sits level. Wipe the joist off with a tack cloth and apply waterproof sealant to it while it’s exposed, to try to prevent further issues.