For when we finish the attic? Plywood floor. Inexpensive paintable floor. A pinner said "Did this in our house...we just put the sheets of plywood down and routed out grooves...then some stain and poly...its been ten years and still looks great and we love it..." Redo floor about $60.00 - plus paint. From: Tidbits from the Tremaynes: When You Just Can't Leave Well Enough Alone.