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Plywood Joint for Epoxy Woody Question

PostPosted: Fri Jan 30, 2015 9:23 pm
by brettstoon
Good Day,

I'm debating on stretching my teardrop to 5X10 instead of 5X8 for the extra room, but I am not sure how to join the 2 sheets of 5x5 Baltic Birch (1/8) for my exterior wall. Right now the plan is to utilize the sandwich method, with 1/8 exterior, 3/4" interior, 1/8" interior. I plan to finish with epoxy and varnish, so I want it to look good. I Know 1/8" ply is too thin to lap joint. Do you just but them up and seal it with the epoxy? I feel like that would be too easy.

I am hoping to not to have to use fiberglass tape because I want a mirror like finish.

Thanks for any suggestions.
B

Re: Plywood Joint for Epoxy Woody Question

PostPosted: Fri Jan 30, 2015 11:07 pm
by tony.latham
brettstoon wrote:Good Day,

I'm debating on stretching my teardrop to 5X10 instead of 5X8 for the extra room, but I am not sure how to join the 2 sheets of 5x5 Baltic Birch (1/8) for my exterior wall. Right now the plan is to utilize the sandwich method, with 1/8 exterior, 3/4" interior, 1/8" interior. I plan to finish with epoxy and varnish, so I want it to look good. I Know 1/8" ply is too thin to lap joint. Do you just but them up and seal it with the epoxy? I feel like that would be too easy.

I am hoping to not to have to use fiberglass tape because I want a mirror like finish.

Thanks for any suggestions.
B


B:

I did a 4x8 with 1/8" ply (5x5 BB) on the interior. I just butted the joints. I think they look fine.
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You might poke around and see if you can find 1/4" subflooring. It's cheaper than 1/4" AC and higher quality. The stuff I get here in the middle of nowhere is gorgeous –I think the face is Russian birch and has "for moist conditions" stamped on the back. You can soak a piece in a bucket and it doesn't come apart. That way you can put the seam where the rear bulkhead since it's 4x8.

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Enjoy your buid.... :thumbsup:

T

Re: Plywood Joint for Epoxy Woody Question

PostPosted: Sat Jan 31, 2015 11:26 am
by brettstoon
T,

Thanks for your response. Your teardrop looks incredible. After seeing the picture you posted with them butted together, I agree - it does look good. I was more worried about the seem leaking, or having too much of a valley to fill with epoxy - but it appears to be very snug. I also plan on offsetting seams on my sandwiched layer so there shouldn't be any worries for strength. I think I'll end up adding the extra 2ft. My thoughts are, if I already have to put in the seam, I might as well just extend it by a little bit. I think the extra few inches will pay pounds for convenience later.

Now just to find a "cheaper" epoxy over the west system.

Was skinning in alumnium very difficult? I do have access to sheets of 60" aluminum - only it is mill finished - so I imagine I will have to find a way to polish or clear to prevent corrosion. Ohhhhh so many things to think about!

Brett

Re: Plywood Joint for Epoxy Woody Question

PostPosted: Sat Jan 31, 2015 11:49 am
by tony.latham
My brain muttered over the skinning process but I found it easy. My tear has mill fininshed aluminum and I think it's fine.

You might try RAKA epoxy, I used it on a cedar strip canoe and will coat my third teardrop with it. http://www.raka.com/epoxy.html I use their pumps and have never had a problem measuring out the proper 2:1 ratio.

As far as wall strength, once the walls are attached to the floor and your ceiling is installed, the "box" is incredibly strong.

T

Re: Plywood Joint for Epoxy Woody Question

PostPosted: Sat Jan 31, 2015 1:13 pm
by KCStudly
Land the seam on a solid part of your skeleton or internal wall frame. That way the joint will lay flat, join well, it gives you plenty of glue surface at the joint, and will be easy to seal the front.

I had good luck getting decent joints by dry fitting the panels (in my case, 5 mm) up against each other and touching any high spots with a small matchbox plan until I was happy.