Question - attaching wood strips to canvas?

[daveesl77]

EDIT - I'll leave this up, just in case someone else does what I did and ignores the obvious answer. Thanks a million to Pete for seeing through my fog and yes this problem (that should not have been a problem) is SOLVED.


The time has come to where in the next few days I'll start building my walls. I've waffled back and forth on a multitude of construction ideas and techniques and now need your opinions.

I "think" I will do a hybrid. Build size is...
Floor - 5'4" x 9'
Outside cabin dimension - 10' curve to curve, 5' high, 5'4" wide.

Using minimal wood framing (wood not ply), but also doing a perimeter wood strip laminate around the outer ring of the walls for stabilization and support of spars. Wood frame members for doors and windows. There will not be an opening galley hatch, but instead a galley that slides out the side. Already did a test on the slide out system and it worked fine. Will be filling all voids with blue board. I'm still trying to decide whether to do 3/4 framing or double up to 1.5 inches depth (not including outer skins). Was told my several that 3/4 is fine, but that really looks thin to me. Anyone that has any further opinions on this, please let me know, open to all suggestions.

Here is the dilemma. My original idea was to skin the inside walls with 1/8" inch ply. On the outside I was thinking about doing 1/4" ply and then to laminate wood strips (mostly western red cedar) that I'm resawing myself to the exterior. I would then epoxy/glass and then polyurethane spar varnish to finish. However, after reading the problems some have run into with lousy plywood sheets nowadays, and having spent a substantial amount of time looking at "foamie" builds, I'm leaning more to not putting ply on the outside and instead wrapping the exterior (interior too?) in TBII 'd canvas. If I did that, then I still want to laminate the wood strips to the exterior walls.

So, if that makes any sense, here are the questions.

1) If I do a canvas wrap and not use ply on exterior, what methods of lamination of wood to canvas has worked and what has failed? I've done canvas glued over ply, then painted, but never wood over canvas. I'd rather not use brads or screws. Or should I forget canvas and just do an epoxy/fiberglass cloth wrap.

2) Without plywood skins, is a 3/4" wall just way too thin, the way I think it is? If so, would 1.5" be ok? I can get .5 and .75 xps and 2" eps, I cannot get thicker than that here (for whatever reason) unless I buy like 40 sheets (not gonna happen). So to make thicker I'll just laminate the xps, not a real fan of eps, but I do know it works well.

3) Have others here done a wood over canvas type woody and if so can you direct me to their build journal and/or photos?

Thank you all so very, very much. I am learning so much here. This old dog is learning a lot of new tricks.

dave

[KCStudly]

If I were to do it over I would have built 60 wide instead of 64. There is plenty of room inside and even with my 1-1/2 inch thick walls it would not have been a problem.

Can't speak personally for thinner walls, but IMO if you are going to strip and glass, I would glue the cedar straight to the foam and not bother with the canvas. You will get all of the puncture resistance and tensile strength you need from a single layer of 6 oz backed up by the wood strips. Why not do a small 2 ft square panel as a test? It would be a great way for you to get familiar with the materials and process, and will prove the concept.

I wouldn't worry too much about finding decent plywood. It is available or can be ordered. Buy the best materials you can afford and don't regret it. By the time you are done with this project you will have more time invested than anything else, so the quality of the materials you use and your techniques to avoid weather intrusion are your insurance policy for the time that you invest.

Build what you want.

[daveesl77]

Thank you KC, I read your entire build journal to this point, and loved the attention to detail you have done.

After I posted the original, I realized I had forgotten a test glueup I did last night, doing exactly what you said. Using raw cedar strips, titebond2 and 1/2 blueboard. Just tried to pry the wood, overhanging by 2 inches from the xps and using a luggage scale, I tore the foam apart at 28 lbs, but the wood/foam didn't budge even with the leverage. My only concern is I want to make as certain as I can that the framework inside the walls is as watertight as I can make it, thus the wrap plus the structural increase.

dave

[pchast]

Dave,

I'm a little confused. Are you planning on glassing the outside after you glue on the strips?
If so, won't that glass provide the structure and the canvas be like belt and suspenders?

[daveesl77]

Pete, you are absolutely right and I have way over thought this, without looking at the logical and most obvious. Duh.

I have honestly been racking my brain all afternoon, thinking of various ways to make this work and the obvious, most sensible answer was there all the time. Now I really feel old.

Anyway, never mind on the question...Pete answered it



dave

[Chuckles]

If I were to do it over I would have built 60 wide instead of 64. There is plenty of room inside and even with my 1-1/2 inch thick walls it would not have been a problem.

Can't speak personally for thinner walls, but IMO if you are going to strip and glass, I would glue the cedar straight to the foam and not bother with the canvas. You will get all of the puncture resistance and tensile strength you need from a single layer of 6 oz backed up by the wood strips. Why not do a small 2 ft square panel as a test? It would be a great way for you to get familiar with the materials and process, and will prove the concept.

I'll second the 60" width. I built mine at 64" kinda by accident... I originally planned on setting the walls on the floor to end up with a 62" width but changed the plan mid-stream to have the walls outside the floor. Now the interior is 64" wide and there is a pretty large gap on the sides of the mattress. Were I to build again I would make the interior 60". Maybe 61" just so its easier making the bed.

As for thinner walls, mine are 13 feet long by 6 feet tall made with 3/4 inch framing and foam. 1/4 inch ply inside and 1/4 inch cedar, glass and epoxy on the outside. when we picked them up off the bench by the ends I doubt they sagged even an inch in the center. I didn't expect them to be as stiff as they were.

Just my two cents.

Build on!

Chuck

[daveesl77]

Chuckles, thank you and others who verify what I've been told about the thickness. As to the width, the idea was (I guess like yours) to allow a standard queensize type mattress width and some variation in wall thickness. The floor width is 64" and then with the walls sitting on the floor that then gives me somewhere around 60 inches inside width. Oh, and on the walls, while the primary wall plate will sit on the floor and be through bolted, I'm making the exterior to where a wide trim piece will wrap around the floor system and also directly attach to the plate.

Love how you did your cedar, absolutely beautiful. Did you resaw it? I'm cutting mine out of several boards and will try to do a design using the various tones as well as a couple of other wood types. I think I like the 3/16 thickness best so far, have gone paper thin, 1/8", 3/16 and 1/4.

dave

[Chuckles]

Chuckles, thank you and others who verify what I've been told about the thickness. As to the width, the idea was (I guess like yours) to allow a standard queensize type mattress width and some variation in wall thickness. The floor width is 64" and then with the walls sitting on the floor that then gives me somewhere around 60 inches inside width. Oh, and on the walls, while the primary wall plate will sit on the floor and be through bolted, I'm making the exterior to where a wide trim piece will wrap around the floor system and also directly attach to the plate.

Love how you did your cedar, absolutely beautiful. Did you resaw it? I'm cutting mine out of several boards and will try to do a design using the various tones as well as a couple of other wood types. I think I like the 3/16 thickness best so far, have gone paper thin, 1/8", 3/16 and 1/4.

dave

Thanks Dave,

The finished thickness of my walls are 1-1/4 inches (1/4 + 3/4 + 1/4). Had I set them on the frame as originally intended I would have had in interior width of 61-1/2 inches.

For my walls I bought rough cut white cedar and re sawed/planed it to 1/4 inch thickness then cut alternating 1/8 inch x 1/4 inch rabbets on each edge (shiplap). I glued and nailed the cedar with copper boat nails. The trim and vertical pieces are ash. I probably would not have had to do the shiplap joints. I could have just edge glued them like a cedar strip canoe since the glass and epoxy seals everything. I'm sure 3/16" boards would work fine. I know some canoe builders use 3/16 cedar for light weight boats.

I still have some more finish work to do this summer. I have some areas of blush in the epoxy and some runs and sags so I plan on sanding it all again and putting on another coat of epoxy followed by a few coats of spar varnish. I also need to make a door that matches the trailer.

Good luck with your build