Screws necessary in sandwich wall construction?

[eagle24]

I used Tightbond II glue and a pneumatic 18 gauge 1/4" narrow crown stapler to attach the outer (1/4") plywood to the 3/4" inner framework. The stapler sped up the assembly process and considerably reduced the need to use clamps and/or weights to hold the pieces together while glue set up. The staples are permanent mechanical fasteners that strengthen and supplement the glue bond.

Somehow missed your reply. This is a good idea for the outer plywood and I have a narrow crown stapler. I'll definitely do this if I put the outer plywood on after the wall is attached. I was mainly trying to avoid any dimpling of the outside to minimize the amount of fairing I have to do after the epoxy/glass cloth is put on. A narrow crown stapler will pull down below the surface and fill easily with epoxy.

[Esteban]

I used Tightbond II glue and a pneumatic 18 gauge 1/4" narrow crown stapler to attach the outer (1/4") plywood to the 3/4" inner framework. The stapler sped up the assembly process and considerably reduced the need to use clamps and/or weights to hold the pieces together while glue set up. The staples are permanent mechanical fasteners that strengthen and supplement the glue bond.

Somehow missed your reply. This is a good idea for the outer plywood and I have a narrow crown stapler. I'll definitely do this if I put the outer plywood on after the wall is attached. I suggest you glue or epoxy and staple the outer plywood to the inner framework before you attach the walls to the floor. Fiberglassing and fairing a horizontal plywood wall is also much easier than fiberglassing & fairing a vertical wall surface. I was mainly trying to avoid any dimpling of the outside to minimize the amount of fairing I have to do after the epoxy/glass cloth is put on. A narrow crown stapler will pull down below the surface and fill easily with epoxy. which makes fiberglassing and fairing easier.

My suggestion is to first glue, staple and attach the outer plywood to the inner framework. Fiberglass and sand/fair the walls while they're flat/horizontal on a work bench or saw horses. That way gravity helps you spread and smooth out epoxy while you fiberglass, and then sand/fair the side walls. When that's done turn over the walls and install rigid foam boards in the cut out areas. I used construction adhesive to securely adhere the foam to the frame and plywood. With the fiberglassed & insulated walls on top of sawhorses you can more easily glue on (or epoxy on) the cabin side plywood to the insulated inside framework. You can also more easily finish the inside cabin wall plywood with varnish, etc.

When all that's done install the completed walls to the floor. It will save you time and reduce the need to do construction work while inside an awkward & confined cabin space

Steve Frederick's "inside out" method of construction can/will save time and be easier on your back. I bought his Shop Manual for building a teardrop trailer and feel it was a good investment. http://www.campingclassics.com/index3.html has links on the bottom of the page to informative & beautiful photos of the trailers he built.