Hi All, I'm going to be doing a bit of work on the ground floor levelling up a suspended wooded floor that is sagging. Will be replacing the old boards which are full of gaps having been ripped up too many times, with 18mm flooring grade chipboard. I would expect that the chipboard flooring will give far better insulation than the old floor boards but is it worth insulating under the floor too? Was thinking of using 50mm Celotex? Any thoughts? Thanks.