RV Repair Question

[James Baldwin]

Hi Group, I have a woodworking RV repair question. I'm in the process of repairing some rotted frame members in our 1996 Caribou truck camper. The frame members are 1 1/2 X 3/4 inch pine which is not a problem to replace. Were I'm having trouble is finding 1/8 inch plywood. The original construction had 1/8 inch Laun/mahogany glued to both sides of the frames then the fiberglass skin glued to the outside. I think that two pieces ( one on each side) of 5mm under layment is going to be too thick. Can I substitute 1/8 inch Masonite or 1/8 inch white board and get stuff to stick to it? I would probably be using construction adhesive and if that won't work then some kind of 3M product. Thanks, Jim

[Bradley Gray]

I made a camper shell out of 1/8" tempered masonite one time. I don't remember what glue I used but it worked.

[Sebastien La Madeleine]

I just went through a similar process and tried hardboard and was not happy... it kept delaminating as soon as I would try to pull it off the frame. I ended up finding some 1/8 plywood that was much better structurally and also had better water resistance. Hardboard just swelled up and would become really crumbly...

[Tom M King]

I seems like there would be FRP (fiberglass reinforced plywood) panels for that application, and I would think that's what the manufacturer would have used.

[James Baldwin]

This camper was built in 1996. The frame has 1/8 inch plywood between it and the fiberglass skin. I'm currently removing the outer fiberglass skin. It looks like I might be able to use 5mm utility plywood. Were the join is it's covered with a piece of metal trim and butyl putty seal tape. I think that the slight difference in thickness will not be noticed as it will be up near the top of the camper. I'll know more when the skin is removed. Jim
Butyl Seal Tape

[Tom M King]

I know some place used to sell repair parts for RV's online, including a big selection of FRP panels, but I forget the company name.

Here is one manufacturer just for a look of the choices: https://www.fiber-tech.net/frp-panels

There are two things that I know of that go by FRP. Fiberglass reinforced plastic, and fiberglass reinforced plywood.

[Ken Combs]

Check with a real lumber yard for door skin material. They may not have it, but maybe can put you in touch with a local door manufacturer.

[Paul F Franklin]

If the 5mm plywood is too thick, could you just make the frame members slightly thinner to compensate?

[roger wiegand]

3 mm aircraft plywood? It's proabably stronger than the original despite being a tad thinner. I buy mine from Boulter Plywood locally (they will ship anywhere) but any good plywood supply place should stock it.

[Maurice Mcmurry]

Shipping is usually a deal breaker for plywood but it is available in 1/8 (3 mm) for boat building.
https://www.clcboats.com/shop/boat-building-supplies-epoxy-fiberglass-plywood/marine-plywood-cedar-strips/?gclid=CjwKCAjwkYGVBhArEiwA4sZLuF0FvjIHCcYRVJsiwV6 sfpbhfx7C-MOP1AZq0mjEJLsU9HjIKAz7VhoCdMIQAvD_BwE

[James Baldwin]

I think that the problem is solved. One of my local Home Depot stores carries 1/8 inch utility plywood in 4 X 8 sheets at about $16 a sheet. I'll be checking on it later today. I want to thank everyone for their help and suggestions. It was the suggestion about door skins that led to Home Depot. Thanks again, Jim

[Tom M King]

Those door skins have the lowest water resistance of any "plywood" I've ever dealt with.

[James Baldwin]

Well I was able to get the 1/8 inch plywood at my local HD. I checked with a local RV repairman on reattaching the fiberglass skin. He used a 3M water base contact adhesive. Contacted 3M and the told me what to use. Just ordered a gallon. A $148 with free shipping. I don't have to replace any of the fiberglass skin as the original skin is just fine. It's the under laying plywood and some of the framing that needs replaced. Jim