clmcg123

i am doing a friends bathroom floor in a couple of weeks.the house has had a large extension to the side,therefor bathroom floor extended about 2mtrs.problem-the original floor is floorboards and the new is plywood.do i cover the whole lot again with plywood,hence making a high step(especially when tiles are on),or could i just prime and adhesive it all AND would it be the same materials i would use on both floors?...ANY suggestions please!!:confused: