Possible woody wall for foamie??

[R. W. Alexander]

I have a question for for those of you who have mastered the ways of the Foam. Would it be possible to add a cedar wood exterior to the foam. And if it is possible... what would be the best way for attaching it to the exterior?
Routing into the foam on the outside after gluing the canvas? Then glue in some vertical wood strips with Gorilla glue?? Or just gluing the wood strips to the canvas with Tight Bond 2??? (I'm just throwing out some ideas) I've attached a side profile of what I am thinking about. Yes it would be more work and maintenance, but I like the look of the Woodie.

[OP827]

I've glued sheets of 1/8" baltic plywood directly to XPS foam (60-80 grit sanded surface) with TB2 or Epoxy with good results. I think you do not need canvas under the cedar strips, instead I would cover the strips with a thin fiberglass cloth and epoxy, similar to a wood strip canoe fiberglassing to achieve proper protection from elements and the wall structural integrity.
You could build a small, say 12"x12" wall piece sample to see if you like it. I am interested to see such test results being shared here

[KCStudly]

I had the same thought at the same time and typed this concurrently :

Since you will have to seal the cedar strips very well regardless of what is under them, my thinking is why bother with the canvas or extra wood? Of coarse test, but why not glue the cedar strips directly to the foam and then glass with epoxy like for a stripper canoe?

It will be strong.

[OP827]

KC, looks like we think alike

P.S. I would definetely try to do one or more samples, just to see how thin I can make the cedar strips to save wood and weight..

[OP827]

R. W. Alexander,
I think your idea is great.
It allows achieving a woodie trailer look and yet have a very light trailer. Yes, I would do a test with routing aprox. 3/8x3/8" vertical grooves in XPS foam say every 10" and then glue thin wooden stringers so that I can simply staple the cedar strips to them w/o any other means of clamping or vacuum bagging. This method should allow to relatively quickly cover the wall sandwich AND have NO foam delamination concerns in the future. A small manual stapler will do a fine job, staple holes will disappear once the glue is set, staples are removed, and wood is wiped with a damp cloth as I saw someone did that on this forum on a teardrop build. So, what do you think?

[R. W. Alexander]

Well what got me thinking about doing a wood wall was Davees77 Conch Fritters woody . I liked how he did the wood with the polyurethane mineral spirits one coat 25%75% then 50%50% then 75% 25% followed by 3 full strength coats. Simular how boats were made waterproof in years past before epoxies and fiberglass.

[OP827]

Well what got me thinking about doing a wood wall was Davees77 Conch Fritters woody . I liked how he did the wood with the polyurethane mineral spirits one coat 25%75% then 50%50% then 75% 25% followed by 3 full strength coats. Simular how boats were made waterproof in years past before epoxies and fiberglass.

Sounds good, just FYI I found hard way that mineral spirit in the mix eats the XPS foam, so when I treated some wood in my build with the mix, some of it made its way inside the foam structure and made a cavity. I repaired it with Great Stuff PU foam.

[GPW]

You sure it was mineral spirits ???

[KCStudly]

Yeah, I have not had that problem. Are you sure it wasn't acetone (which eats foam like there is no tomorrow)?

[daveesl77]

Yeah, the mix should NOT be used with the foam side! On Conch Fritter we have foam, then 2mm ply, then the cedar. Ply was glued directly to foam and wood framing, then sealed with the mix on the outside. The cedar strips (about 3/16" nominal) are then glued to the ply. The cedar is then sealed and coated with an additional 4 coats of full strength poly. I did not use epoxy, but it would have made it easier had I done so, then covered the epoxy with 1 or 2 coats of poly for the UV protection.

The cedar could have been glued directly onto the foam, but the weight of 2mm ply vs it's structural ability and seal made it a choice to use.

dave

[GPW]

We’d put the cedar boards with the coves on top , so the water will run out ... as shown would be little reservoirs ...

More testing on the Foam /Mineral spirits refutation.. Getting my “scraps” out ...

[GPW]

Tested just now ... Four different foams ... First coat of pure Mineral Spirits , then a dab of pure Poly ..... Although you can see pooling of the poly there is no signs of any melting ...

[daveesl77]

That is interesting GPW. I just assumed that since mineral spirits/paint thinner was petroleum based it would melt the foam. Keep us up on your tests, this could change things.

dave

[GPW]

All dry now ,. no signs of any melting... here’s a pic from a minute ago ...

[OP827]

I am sure it was not acetone, I'll make some pictures of the thinner and damage once I am back at home.