Thanks for the input...we live in California and the trailer will most likely be stored in desert area.  Temps in the 100's are common in summer months and the area does get snow at times in the winter. What is your climate like? 

The resins used in the fiberglass layups will degrade with UV exposure. The hotter the days and the more sun the roof is subjected to, the shorter the life span will be of the FRP layup. Unless the wax is a marine grade product with a high amount of UV protectors, waxing the roof will have little affect to prevent damage. The life span of the wax is short, and reapplication could be frequent depending on your environment.

It is easy to test for damaged resin. Wet your finger and rub it across the fiberglass surface. If this results in a whitish powder, the resin has been damaged. Depending upon the exposure, this can occur in 5-10 years. The easiest and longest lasting repair is to then sand the roof and coat it with a white paint.

There are many types of materials used in the construction of a FRP roof. Different manufacturers will use different ones, depending on their budgets and commitment to quality. It is difficult to directly compare the life span of various trailers, unless they were owned in the same location and conditions.

It takes a couple of minutes to inspect the roof. Painting a roof is a half day DIY project. Fiberglass and aluminum are excellent roofing materials. After restoring three different steel roofs, I have firm plans to not own another steel horse trailer.

Check out the SafeBump roof system, cool and durable

http://www.doubledtrailers.com/Video/technologies/safebump_and_safekick.htm

Bartley Heath
bartley@DoubleDTrailers.com
Buy Factory Direct and $ave at DoubleDTrailers.com

The life expectancy of a fiberglass roof will depend on the quality and the materials used to make it.  But go down to any marina and look at the 10-15 year old boats that sit out in the environment 365 days a year and see how the fiberglass holds up.