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Plywood thickness

PostPosted: Wed Mar 13, 2013 4:43 pm
by Irving
What thickness of plywood have you used for the interior as well as exterior walls of your build? If you have insulated - what thickness insulation foam board have you used?

After exploring the idea of a "foamie" build I am blown away that you can build almost the whole thing out of foam board and have it be structurally sound.

I am considering the idea of using just 7/32" plywood for both the interior and exterior walls and putting 1.5" foam insulation in the middle. This is a huge departure from my original plan of using 1/2" plywood on the interior and exterior.

Re: Plywood thickness

PostPosted: Wed Mar 13, 2013 7:29 pm
by Woodbutcher
The one trailer I built that was completely insulated I used 1" foam between 2 , 1/4" sides. There was a stick built frame as well. Not a foamie.

Re: Plywood thickness

PostPosted: Wed Mar 13, 2013 7:47 pm
by Irving
Woodbutcher wrote:The one trailer I built that was completely insulated I used 1" foam between 2 , 1/4" sides. There was a stick built frame as well. Not a foamie.


What do you mean by "stick built frame"?

Re: Plywood thickness

PostPosted: Wed Mar 13, 2013 8:36 pm
by OuttaHand
Mine is 3/4" exterior ply, 3/4" foam insulation, with 1/4" plywood on the interior.

Re: Plywood thickness

PostPosted: Wed Mar 13, 2013 8:38 pm
by Woodbutcher
Irving wrote:
Woodbutcher wrote:The one trailer I built that was completely insulated I used 1" foam between 2 , 1/4" sides. There was a stick built frame as well. Not a foamie.


What do you mean by "stick built frame"?





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Re: Plywood thickness

PostPosted: Wed Mar 13, 2013 10:35 pm
by Gage
I build my teardrops with 1/2" outside ply (main wall), 3/4" foam then 1/8" inside ply. That's what works for me ;)

Re: Plywood thickness

PostPosted: Thu Mar 14, 2013 7:52 am
by Bigblock352
I'm using 1/2 ply with cut outs with 1/2 foam in the cut outs for the main wall with 5 mil outside and 1/8 inside.

Re: Plywood thickness

PostPosted: Thu Mar 14, 2013 12:01 pm
by Vindi_andy
Mine is similar to woodbutchers 1/4" in and out with 1" insulation between and simple stick frame. Had even less sticks then wood butcthers. 1 either side of door and window running top to bottm and one where the galley bulkhead will be. Just enough to join the 2 faces together. Still pretty heavy things.

Re: Plywood thickness

PostPosted: Thu Mar 14, 2013 4:03 pm
by dwgriff1
1/8 almost everywhere.

Re: Plywood thickness

PostPosted: Sat Mar 23, 2013 5:02 pm
by Irving
So I am building my walls with 1.5" foam insulation and 1/8" hard fiberboard on the inside and most likely 1/4" OSB (chip board) on the outside. I am going to be covering the entire outside and bottom with canvas and tightbond 3.

I'm still a bit hung up on using the OSB board. I almost bought a bunch of 11/32" plywood but decided it was too heavy and put it back.

Should I be talked out of using 1/4" OSB board? Any good reasons not to use it? It is just so cheap at $9.50 for a 4x8 sheet and it's quite lightweight. I'm having a tough time finding inexpensive 1/4" plywood in my area.

Re: Plywood thickness

PostPosted: Sat Mar 23, 2013 5:43 pm
by 48Rob
Should I be talked out of using 1/4" OSB board? Any good reasons not to use it? It is just so cheap at $9.50 for a 4x8 sheet and it's quite lightweight. I'm having a tough time finding inexpensive 1/4" plywood in my area.


Though some have used OSB, it is a poor choice as it will break down very quickly if moisture finds a way in.
If it will be completely encapsulated, it might hold up, but it is quite a risk to take.

In my opinion, 1/4" OSB is not anywhere near as strong as 1/4" plywood.

Rob

Re: Plywood thickness

PostPosted: Sat Mar 23, 2013 7:25 pm
by Irving
48Rob wrote:
Should I be talked out of using 1/4" OSB board? Any good reasons not to use it? It is just so cheap at $9.50 for a 4x8 sheet and it's quite lightweight. I'm having a tough time finding inexpensive 1/4" plywood in my area.


Though some have used OSB, it is a poor choice as it will break down very quickly if moisture finds a way in.
If it will be completely encapsulated, it might hold up, but it is quite a risk to take.

In my opinion, 1/4" OSB is not anywhere near as strong as 1/4" plywood.

Rob


Not the answer I wanted to hear. haha Yes, it is going to be very encapsulated. The roof, walls and underbody are going to be covered in canvas that is sandwiched between layers of waterproof tightbond 3. Then primer and paint.

Re: Plywood thickness

PostPosted: Sun Mar 24, 2013 1:12 am
by Kody
My TD will be built using 1/2" ply for the sides, no insulation. The bulkheads will be 1/2" ply, the galley will be 1/2" ply and the ceiling and roof will be 4mm. All glue for woodwork will be Titebond 3.

Kody

Re: Plywood thickness

PostPosted: Sun Mar 24, 2013 8:35 am
by 48Rob
Not the answer I wanted to hear. haha Yes, it is going to be very encapsulated. The roof, walls and underbody are going to be covered in canvas that is sandwiched between layers of waterproof tightbond 3. Then primer and paint.


Hi Irving,

I may be misunderstanding your explanation/plans??

If the glue and canvas will be on both sides of the OSB, and also cover all sides and ends, you might be okay
If the glue and canvas is just on the exterior, the OSB will still absorb moisture.

If you try it, be sure to pay extreme attention to anyplace your complete seal is broken, such as window openings, vents, and especially screws or other fastener penetrations.
I'm a fan of installing fasteners, then removing a few at a time and injecting sealer in the holes before replacing them, to seal both the head and threads of the screw, and the raw material exposed by placing the hole/screw.

Rob

Re: Plywood thickness

PostPosted: Sun Mar 24, 2013 2:41 pm
by Irving
Ended up picking up 5.5mm (7/32") plywood for the exterior.

http://www.homedepot.com/p/5-5-mm-7-32-4-ft-x-8-ft-Underlayment-431178/203183022#.UU9WuDeyItY

It feels quite hard and sturdy for as thin as it is..