Question on wall thickness and composition?

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Question on wall thickness and composition?

Postby daveesl77 » Thu Feb 26, 2015 8:33 pm

Getting ready to start the framing and build on my wall system. I went way overboard on my floor build and now see that I can definitely scale back on sizes. However, I'd like to know what you folks think about my planned wall build and what may or may not be better (worse) ideas.

Here is what I have so far...

4x8 HF 1720 trailer, welded and bolted. I also added in a 2x2 steel square tube for both a tongue stiffener and extender, bolted and welded to the 2nd crossmember back and goes 18" beyond the original length.

Way overbuilt my floor being that it is 1/2" ply, 1" wood and blueboard filled interior section, 1/2" ply. All areas are sealed, glued and screwed. Underside is canvas titebond impregnated then covered with 2 coats of Kool Seal. Top side is triple sealed poly using mineral spirits:spar poly at 75:25, then 50:50, then 25:75. Tested in a big rain overnight and what water got into my temporary garage just beaded up. Floor size is 5'4" wide x 9' long.

I've changed my initial design from a teardrop(ish) to more of a semi-standy. Curves front and back. 5' 5" outside width, 10' outside curve to curve length, 5' height. Yeah, I know that once I blew past 4x8 I should look at sizes that equate to a multiple of those type numbers, but I'm weird. :) There will be no hatch opening for galley. Instead, galley will be internal, but will be able to slide out the side . Not worried about tongue weight, as I've ramped up the tongue system and I will put things such as battery and water to the rear of the axle (if needed). I've found multiple videos on how others built similar systems and they all seem to work pretty well. Reason I'm doing this is so that if I don't want to open up the galley, say really bad weather or an overnight stop, then it works inside and I still have some floor space for my dog. If I do slide it out, then I have a pretty sizeable amount of floor space. Reason for the 5' height is so we can sit up inside if we want. Don't really care if I stand or not.

My idea on the walls construction, unless you wonderful folks think I should do something different is as follows...

I'm ripping 1 x 10 pine boards that I picked up as culls, but they are actually beautiful boards into mostly 2" width so they'll be 3/4 x 2 true size. Some, such as ones around door frame, windows and the galley structure support area will be 4 or even 6" wide. Curves will all be done using laminated 1/8 pine, bent to shape. All wood will be fully sealed. These framing members will then be glue laminated to 1/4 ply (maybe I should use 1/8 ?) for exterior. Over that I'll be gluing 3/16" thick by 1.75" wood strips I'll be resawing from dimension lumber. All voids will be fully filled with xps foamboard, laminated to the wood. Inside I want to use 1/8 ply, once again laminated to the wood framing and insulation. So the actual total wall thickness would be 1 5/16, glue-laminated, fully filled with foam and wood.

So, am I building the walls too light, too heavy, or properly? My floor system has an unsupported overhang of 7" on the width and 12" on the rear. I weigh 220 and can jump on the corner without any noticeable flex and can stand with no measurable deflection. Like I said, I way overbuilt it and don't want to repeat on the walls and ceiling, but at the same time I don't want to make it too flimsy either. Any opinions are greatly appreciated and feel free to critique all you want, I like criticism.

Thanks in advance,

dave
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Re: Question on wall thickness and composition?

Postby aggie79 » Thu Feb 26, 2015 9:19 pm

Dave,
I look forward to your build. One of friends has a 5' tall teardrop and that extra foot is really spacious.

Regarding the framing, there really is no need to go beyond 2" or so in width. It will be plenty strong. On your exterior sidewall finish, if you're going to epoxy over everything, I'd leave out the plywood. For the interior, 1/8" plywood is more than strong enough.
Take care,
Tom
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Re: Question on wall thickness and composition?

Postby daveesl77 » Thu Feb 26, 2015 10:19 pm

Thank you for the information. On the exterior wall I want to do the wood strips simply for the look, I'm trying to decide between doing shades of a single wood or a blend of multiple types. I intend to cover it with epoxy and then spar varnish exterior. I'm an old sailor and love doing wood stuff. Aluminum and paint look great, but I just love the look and feel of wood.

EDIT: I just realized you said I could leave out the ply. If so, should I increase the internal wall thickness from say 3/4 inch to 1.5 inches?

dave
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Re: Question on wall thickness and composition?

Postby Chuckles » Thu Feb 26, 2015 11:31 pm

Sounds line you are on the right track Dave.

For my walls I used 3/4 inch framing (poplar) with foam infill. 1/4 inch plywood on the inside and 1/4 inch shiplap cedar boards on the outside (no outer plywood at all). The walls are plenty strong even without the 6 oz glass and epoxy. For strength and stiffness you really don't need to go any thicker than the 3/4 inch insulation... especially if you glue it all up in a stress skin panel.

108861 108862 109631

Mine is a semi standy as well... 13 feet long x 64 inches wide.

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