Fiberglass Roof

Having had a membrane roof on a TT and a fiberglass one on our View, it is no contest. Fiberglass is the way to go.

One piece is advertising words of art. Yes it is "usually" one piece fro fromt cap to rear cap on shortish RVs..... but it has a bunch of holes cut in it for the A/C, vent stacks, moon lights and sky lights, fans, antennas, etc..

It is not about "one piece", it is about how well it is sealed.

Modern WBGOs have rolled edges that come down over the sides and join at a small gutter so water runs off the side below the top/side interface.

You want to be VERY careful getting on top of a FG roof. I use big fat bathroom/kitchen rugs grippy side down to spread out pressure points of feet and knees. If you are uncomfortable working above ground....stay off the roof!

I was told that the fiberglass on a Bounder is 3/8 thick. I know the fiberglass on my 2017 Jayco is not anywhere near that. The fiberglass roofs are superior in that you do not get black streaking down the side of the coach, but you need to be careful with the edge area's from limbs or impact damage. I walk on mine without any problem but not near the round over edge area. On my rig the roof is crowned. Another bonus is you don't get that dirty moldy look that the elastic roofs have. I think that it would lighter too.

As mentioned fiberglass covers a wide range of materials, from thin roll materials like Filon, to thick solid boat hull like fiberglass. Of course the thicker it is, the heavier it is, and being the roof it is at the top of the coach, potentially making it more top heavy and less stable.

Some fiberglass roofs are basically taped down along the side walls, and this seal must be checked and maintained or else the wind might get under it and peel the entire roof off. So while fiberglass may be more durable than the TPO and EPDM rubber roof material, it is not maintenance free.

I think all class C roofs, no matter what the material, would qualify as one-piece. I would be shocked if any maker pieced together multiple pieces of material for the roof covering these days. (That's not to say that, for instance, the front cabover section and the roof are a continuous piece without a seam.)

There are differences in how thick the fiberglass is, but finding out that information between manufacturers is tricky at best. There are also differences in how the edges are sealed and assembled to the walls, and possibly in whether the roof is crowned at all or perfectly flat (crowned, at least slightly, being decidedly better).