New Fiberglass Roof - 1985 Toyota Coachmen

[NCbugman]

I’ve completely torn off a damaged roof, and replaced it with laminated cambered rafters, covered with a skin of 1/8” poplar.
I now intend to cover that with fiberglass using West Systems epoxy.
My question is: What weight and type of fiberglass cloth?
I have some experience with boat hulls, but a camper roof is a different beast.

Thanks!

[wolfe10]

Look into using sheet FILON.

[Argosy]

I was going to say a layer of mat then a couple of layers of cloth then I wondered how far apart are the rafters? You want it strong enough so you can get on it without it flexing so the fiberglass delamintes from the wood.

[NCbugman]

Laminated rafters are quite strong, and about 9” apart.
I worked on top today. Distributing my 200# between two rafters was no problem.

I have boat building friends who are advising some serious $$$ fiber, but I’m thinking that a camper roof doesn’t need it.

I was hoping that someone could take me to school.

[Argosy]

I wasn't as concerned about the rafters as the spacing with a 1/8" deck. I wasn't expecting 9" centers.

I'm with you and don't see any real need for anything exotic. Keeping it sealed and protected over time would be more critical to me.

[Duck Tape]

I used 1/4" marine-grade plywood to re-side my 1992 36-foot Monaco, adding 2 layers of 4 oz. e-cloth to the outside surface, with the layers staggered so they didn't line up with the wood joints. I used West System epoxy resin.

You won't get a lot of strength from the fibreglass in compression so I wouldn't worry too much about using heavy cloth, your main goal should to make the roof waterproof and to protect the wood from the elements.

When I did my layups I used peel-ply on the top layer, it seemed to me it made the resin more water-tight and it leaves a nicely stippled surface to apply whatever UV protection layer you have in mind. If you don't use peel-ply I think you will have to manually remove the curing residue from the resin before you apply the UV protection.

Good luck,

[amosnandy]

Originally Posted by NCbugman

I’ve completely torn off a damaged roof, and replaced it with laminated cambered rafters, covered with a skin of 1/8” poplar.
I now intend to cover that with fiberglass using West Systems epoxy.
My question is: What weight and type of fiberglass cloth?
I have some experience with boat hulls, but a camper roof is a different beast.

Thanks!

I would seriously consider putting Fibron rather than trying to lay glass mat. If you use glass on something like this, you would want to use woven cloth, many gallons of resin and then when done at least 3 coats of gel coat. Un-coated fiberglass absorbs water so you need good gel coat.

Since you rafters hold you well, and you put down as skin, (I would use luan rather than poplar ) you could buy 8’ wide fibron and glue it down with two part contact adhesive, caulk the edges and it will outlive you.

Probably 1/4 the cost and 1/20 the time.