Bumpyroad wrote:
...and if fiberglass falls apart if not painted, there are about 2.3 million unpainted fiberglass boats floating at marinas that will quickly be sinking.
Boats are made in a mold from the outside in. The first layer
(therefore the outer most) is gelcoat. As Wikipedia says
Gelcoats are designed to be durable, providing resistance to ultraviolet degradation and hydrolysis
I happen to watch a YouTube channel called Sail Life. The guy just replace the entire deck on his 32+' sailboat. He used MULTIPLE layers of 'glass and cross oriented it over all new core material. Then he applied a couple of primer coats of paint and a couple more finish coats making specific comments that the finish coats are UV resistant.
Clearly an RV roof would not need that many layers of 'glass because the roof is not going to support multiple people walking on it AND it probably has more trusses than this guys sailboat.