TD Sidewall Thickness

[fseider]

Newbie here. I know this has been discussed, but I'd like to try to get a more definitive answer to THESE specific question:

For a 4X9 TD:

1 - Will a wall made from 1/8 ply - 3/4 foam board - 1/8 ply (sandwich) be sufficient? (No other covering aside from a finish)

2 - Does it need to be fiberglassed on the outside?

3 - If the above is not good - what is the absolute minimum sandwich wall one should consider? (Must have some insulation)

Thanks in advance for your responses!
Fred

[john]

I built up my walls and made them 1" thick.
3/4" ply was cut out for weight savings and voids filled with styrofoam.
I them covered both sides with 1/4" masonite on one side and luan on the other.
The 1" wall turned out being a little hard to trim around the doors.
A 3/4" wall would have been easier as I would have been able to find trim to fit much easier.

[starleen2]

1 - Will a wall made from 1/8 ply - 3/4 foam board - 1/8 ply (sandwich) be sufficient? (No other covering aside from a finish)
Yes, with some added furring strips for rigidity. 1/8 ply gets a little wavy and bendy without some kind of support. (although some have done it purely with the method above.)

2 - Does it need to be fiberglassed on the outside?
Depends on how you want it weather resistant. It can be epoxy coated or painted – again – your choice. But It doesn’t absolutely HAVE to be fiberglassed

3 - If the above is not good - what is the absolute minimum sandwich wall one should consider? (Must have some insulation)
Moot question since the above are good starting points

[toypusher]

1 - Will a wall made from 1/8 ply - 3/4 foam board - 1/8 ply (sandwich) be sufficient? (No other covering aside from a finish)
Yes, with some added furring strips for rigidity. 1/8 ply gets a little wavy and bendy without some kind of support. (although some have done it purely with the method above.)

2 - Does it need to be fiberglassed on the outside?
Depends on how you want it weather resistant. It can be epoxy coated or painted – again – your choice. But It doesn’t absolutely HAVE to be fiberglassed

3 - If the above is not good - what is the absolute minimum sandwich wall one should consider? (Must have some insulation)
Moot question since the above are good starting points

I would advise against furring strips and go with standard 1x(2 or 3, etc) for framing. (I know that 'furring strips' can be of different materials, but the stuff sold as furring strips is what I am talking about) Furring strips are not a full 3/4" thick and tend to vary a bit in thickness. Standard 1 inch is really 3/4" thick and matches the 3/4" thick ridgid insulation. You will want to put solid framing in the walls where you are going to attach bulkheads, etc.

[bobhenry]

Mine is 1/4" luan only on the nose and I was seriouly concerned that it could easily be penetrated with road debris and flying gravel. If you are worried about bending 1/4 don't be. I filled a presure sprayer with hot water and soaked both sides and did a test bend to 18" diameter so my 2' radius ( 4' diameter ) was done dry. Light construction is great but is 1/8" outside really enough ? Let us know down the road. You can always veneer it later if needed.

[dmckruit]

I was thinking about doing something similar. I have 3 good sheets of masonite (dry erase type) board that I wanted to use for the interior that I have left over from another project. I figured I could sandwich foam board between these and another piece of masonite with wood strips between to hold everything together. I figured this would be a cheaper alternative to buying 10 foot plus long sheets of plywood for my Grumman 2 build. Since I am going to cover the exterior with aluminium sheet, I was thinking of also buying the thin foam underlayment used for Pergo type wooden floors between the outer masonite wall and the aluminum. This would even out any defects in the wood and or where the panels join. The inside seams would be covered by pieces of oak trim.

[del]

My trailer has 1/8 mahogany ply for a outside skin. It is covered in fiberglass and exterior latex.


I have about 7000 miles on the trailer.

del

[jimqpublic]

My Chalet's wall and roof panels have a 1" extruded polystyrene foam (XPS) with 0.045" Filon fiberglass reinforced plastic outer skin and 3 mm (1/8") inner plywood skin. There are a few pieces of wood in the panels. Since it's a folding trailer the edges all have aluminum extrusions to allow it to join.

EDIT: Corrected inner skin to say 'plywood'.

[PaulC]

My trailer has 1/8 mahogany ply for a outside skin. It is covered in fiberglass and exterior latex.


I have about 7000 miles on the trailer.

del

Can't say I'm a big fan of the trailer, Del, (sorry Mate), but I love the tow car.
Cheers
Paul