I'm replacing (today) the rotten chipboard on my groundfloor bathroom roof with 18mm wbp plyboard (8' x 4')
What side faces the elements/takes the felt underlay? (there is a light side and a dark side) the dark side has an origin stamp on it.
Many thanks.
What side faces the elements/takes the felt underlay? (there is a light side and a dark side) the dark side has an origin stamp on it.
Many thanks.
