I have a 140+ year old house in a historic district. It has first and second floor wrap-around porches. The second floor porch has no roof. The second floor porch floor is tongue & groove boards about 3" wide. They are painted with a high gloss paint. On top of the 2nd floor porch floor are the posts and railings. Underneath the floor is tar paper. The 1st floor porch ceiling is beadboard that has pulled away from the framing because of the water leaking through. When it rains, water pours through the 2nd story porch floor. What are my options in waterproofing the floor? I would prefer not to tear up the floor because the railings and posts attached to it.
One suggestion was to fiberglass coat the floor. Another option was to cover it with a waterproof underlayment like GAF Stormguard (which would have to be covered since the sun's rays will destroy it)