Need a good bottom

[Tx River Rat]

A question about plywood thickness for the bottom of trailer( how thick)
I am going to build a T@B look alike or a et similar in construction to the Puffin. I also live in TX and the insulation I don't think is needed. 1/4 walls
glassed and painted. any advice is appreciated.
Ron

[madjack]

...a good grade of cabinet type ply, at 1/2", set on 24" centers should work.................................

[TPMcGinty]

...a good grade of cabinet type ply, at 1/2", set on 24" centers should work.................................

Madjack, Do you recommend cabinet grade plywood for the bottom of the trailer that is exposed to the road or just the one used as the floor of the trailer?

[Gage]

...a good grade of cabinet type ply, at 1/2", set on 24" centers should work.................................

Madjack, Do you recommend cabinet grade plywood for the bottom of the trailer that is exposed to the road or just the one used as the floor of the trailer?

Hmmmm, I think I may have screwed up. I got a 5'x9'x1/2" ply ping pong table top for my floor at the local lumber yard. One side faces the mattress and the other faces the ground. A course the underside is spread with under coating, 1/8" to 1/4" thick. Just something more to confuse you with.

[Tx River Rat]

Madjack
Why cabinet grade ply for the floor.
Ron

[madjack]

...for all...we use an 11ply cabinet grade ply for floors(1/2") and 13 ply 3/4 cabinet grade for walls...common ply...even AB grade will be 5ply and 7ply respectively(if your lucky)...the additional plys makes for a more stable product(resists warpage better)...further... we get our ply from a cabinet shop supplier and it is a Baltic Birch outer veneer with a poplar core and I have never found a void in it...this not the cheapy chi-ply stuff you get in the box stores nowadays...we also seal EVERYTHING with several coats of either a solvent based urethane or an epoxy...we consider this to be very cheap insurance for our peace of mind!!!!!!!!!!
madjack

p.s.FYI... we get this product at wholesale from our supplier...averages around 30bucks(or less) a sheet............MJ

p.s.s...TP, we don't build composite(sandwich) walls or floors...MJ

p.s.s.s. Gage, the only pingpong table material I have been able to find is made of particle board...we ship all the good stuff out Cali and up to NY...or overseas.........MJ

p.s.s.s.s....after saying all of that...use the best materials you can find/afford and a bargin is not always a bargin in the long run...as someone famous once said...the cost is forgotten as soon as the fun begins(or some such)!!!!!!!!!!!!MJ

[slipperyd12]

Hi

I found some 3/4 foam insulated grage door panels that work great. I put silicone in the two seams and lock them together. This has proved to be very water proof and I can pressure was it if I get on a dirt road. Check my album. I am just not a fan of putting plywood where water can contact it. I think it weighs less than 3/4 plywood. I am usually guilty of overkill on my projects.
Just a thought!!!
John[/img]

[Dean_A]

I used a sandwich of 1/2" ply top, rigid foam interior, 1/4" ply bottom. Bottom is coated with asphalt emulsion.

So far it is holding up quite well to the rigors of sitting in my garage!

[Esteban]

I'm building a 5'3" x10' TD and want to keep its weight down. The trailer frame has cross pieces on 2 ft. centers so that'd be the longest unsupported floor span. Would a ladder/sandwich floor of 3/8" plywood on top, 3/4" (or maybe 1 1/2") of rigid foam, and a bottom layer of 1/4" plywood (or possibly even lighter 1/8" plywood) be strong/rigid enough?

I estimate that each 1/8" of floor plywood weighs around 20 pounds for a 5'x10' floor. So each 1/8" of plywood not used is a substantial weight savings.

[Dean_A]

I'm building a 5'3" x10' TD and want to keep its weight down. Would a ladder/sandwich floor of 3/8" plywood on top, 3/4" (or maybe 1 1/2") of rigid foam, and a bottom layer of 1/4" plywood (or possibly even lighter 1/8" plywood) be strong/rigid enough? .

Steve,
In retrospect, that's the route I would have taken, I think 3/8 would be fine for a floor if it's supported by rigid foam, and you keep the dancing to a minimum.

I know some folks just leave the foam exposed on the bottom and don't use a skin at all. I would think 1/8 should be fine. Just waterproof it real well and caulk the seams where the skin meets the frame.

[Esteban]

Thanks for your quick reply Dean. I've been hesitant to use 3/8" plywood for the top of a sandwich floor fearing it might not be strong enough. I'm going to fiberglass the roof of my teardrop and epoxy the sides, I might epoxy the bottom plywood too to seal it.

Funny you replied as I was editing my question. San Diego, your home town now, is where I grew up. Once I get my tear done I'd like to visit to see how it's changed since the late 60's when I last lived there. Maybe I'd camp at Torrey Pines SP north of La Jolla.

[Dean_A]

Steve,

Assuming it's a standard teardrop, the mattress should help distribute the weight as well. I'd also put in a few cross braces that lined up with the cross braces on your trailer. I used 2x4 ripped down to 2x2s.

It's pretty amazing how solid everything becomes once it all gets glued, screwed and assembled.

The population of San Diego County was about 1 million back in 1960. Now it's about 3 million. I can't imagine anyone seeing that as an improvement. Of course, it's still beautiful, and the weather's darn near perfect. You just have to be careful what time you get on the freeways or you'll find yourself in a parking lot instead.

Luckily I'm self-employed, so that gives me the flexibility to work around the crowds. If I had to join the lemmings on the morning/evening commute I thnk I'd go insane.

[Esteban]

Dean, I'm planning to build a ladder-like inner wood floor frame that lines up with the trailer frame and cross pieces below the sandwich floor. In addition I plan to run the top 4'x8' plywood lengthwise and another 1'3" wide x 8' long piece lengthwise beside it to get a 5'3" wide floor. I'll glue them to an inner batten board lengthwise at the plywood joint, between the top and bottom plywood, that'll strengthen/stiffen that part of the floor - on "my side" of the trailer.

By using 3/8" plywood for the top of the sandwich floor, then the inner wood ladder frame and rigid foam, with a 1/8" bottom skin, it may cut down the weight by about 40 pounds compared to using 1/2" ply for the top and 1/4" for the bottom.