I'm replacing the old floor boards with a new 18mm oak floor in our hall and livingroom, but Im not sure if its best to just lay the new floor straight on to the joists or put down a chipboard layer first to cut down any draughts as our bungalow can be a bit cold. If I use the chipboard would the 18mm t&g loft flooring do? The local diy shed has a deal going and I have a few packs over from when I did my loft.