Foam & Fiberglass Roof Rebuild

[flysar]

For months I have been rebuilding the roof and replacing the fabric on my pop up camper and I'm not very far along, probably because I'm not so sure of the best way to build.

Hallmark in 91' sandwiched some 1x lumber and rigid foam between 2 pieces of thin aluminum. I cant save & reuse the aluminum because of all the glue and creases while separating the skins.

I thought I'd build a frame and sandwich the frame & foam between luan and then cover the roof with EPDM or similar but thought that might get to heavy.

Searching the web last night I found a guy building a pop-up camper similar to an Alaskan but out of foam & fiberglass. I've done a little fiberglass work on wood drift boat and it will probably be a lot lighter than luan and EPDM construction. I would hand lay the resin and fabric on the wood frame/foam roof (no luan) and use 1/8" maple ply for a warm wood feel on the ceiling.

Since I don't need a walk-on roof and will only install 2 vents and the original aluminum rack for a canoe I think the original thickness of 3/4" foam should be fine. I'd use taller 1/8 ply around the edges to act as a seal for the top & main body when closed.

Any fiberglass & foam experts out there that can comment on my idea? Happy to send you my phone number in a PM to talk about it.

I'm pretty sure this is the route I want to take and now feel I can get the Hallmark back on the road in short order.

[bb_94401]

My trimaran extensively uses fiberglass covered aramid honeycomb sheets. Very light weight. Amazing sheer strength. Very rigid. No aluminum honeycomb to corrode. These were 1/2" thick. They were surplus from Boeing in the NW. Can be made even stiffer by glassing in a few stringers. Divinycell / carbon fiber sandwich used for curved deck and hulls.

Fasteners into the core material need sufficient backing plate/washers. Good practice is to drill hole, remove some of the honeycomb between the sheets and fill with epoxy. Re-drill hole or use a straw in the epoxy. Avoids compressive damage to core.

If you go the do it yourself route either DIAB divinycell (PVC closed cell foam) or Gurit corecell (Styrene Acrylo-Nitrile (SAN)) closed cell foam works well sandwiched between glass or carbon fiber. Consider learning vacuum bagging. Lower epoxy to fiber ratio, thus same strength, but lower weight.

Same approach needed to avoid compressive effect of through fasteners.

[Joe417]

There's a material called Nidacore that is a honeycomb material with any skin combination or thickness you want(probably other brands too). It was about $90 per 4'x8'x2" sheet but haven't looked in several years. You usually can find it where there are boat yards and builders.

My brother used it to make his roof for a fly bridge on his boat. There's a blog online where a guy and his wife built there own TC out of it to go on a Toyota.

You might be able to use it with aluminum angle and not have to do any fiberglass work. It's some strong and light material so should work well for a popup roof. I belive it was 32# for a 4x8x2".

Good luck with the project.