I have offered to board my girlfriends loft so it can be used for light storage, my original plan was to cross batten a 8' x 10' section (to allow for the insulation) then board this section with 8' x 2' 18mm flooring. However tonight I have had a look up there and the joists appear to be 80mm x 35mm - I was expecting 100mm x 50mm, but these appear extremely thin. Is it still possible to cross batten and board, or is it best left well alone?