Ok I’m trying my luck here hopefully trying to find answer. I have a 1930’s detached house, which has suspended wooden floors With joists that sit on timbers laid across small sleeper walls which are one / two bricks and a piece of slate (acting as DPC I guess). My issue is that all my air bricks run level with the joist height. So if I insulate between the joists with 100mm celotex (or similar). Should I fill the edges with expanding foam and try and make a piece of foam fit that divert’s air down slightly? Any help greatly appreciated.