Just planning bathroom revamp , using reclaimed floorboards, would you recommend a waterproof membrane under boards for extra protection
While membranes are great under tiles, I’m not a fan of waterproof membranes under wooden floors in wet areas. If water seeps down, it needs to get out or evaporate – good airflow and well-sealed timber are the better bet.
Trap water with a membrane, and you can accelerate timber decay. Sorry, I can’t be more specific as a lot depends on your specific application.