The wood floorboards of my hallway move up and down over the the cross beams. This causes creaky floor.
I can access under the house but even with full arm stretch I can't reach the gaps to put in shims. My access stops by the wall along the hallway and there are small spaces you can put your arm through.
A pressurized polyurethane foam with a long nozzle should reach and help get in the smaller gaps.
Would this product work? When people walk on the carpet this will put a lot of pressure on the wood underneath. Would that break/deform the cured foam?