external wall thickness for a bondwood

[gerrynshaz]

Hi 
Im after some advice on replacing the external lining on my bondwood.   I have maranti frame and 3 mm internal lining. 

I was looking at 3 mm external marine ply.

Thoughts? 

[tooleyau]

We used 6mm Marine ply for our restoration project for the sides only. It gives the Meranti something to bond with and provides more rigidity than 3mm.. The 3mm ply us too flexible for sides. However, for the roof we used 3mm. Its flexible enough to form the curve of the roof.

See our restoration at the bottom of this page. vintagecaravans.proboards.com/thread/13769/1940s-bondwood-caravan-originally-posted

However, having said all that you should replace like with like. If the existing external ply on the sides is 3mm, replace with 3, if its 6mm, replace with 6.

Mike

[sportsman 1]

Hi Gerry,

my Clipper had 3 mm masonite originally, I replaced it with 3 mm marine ply made into single sheets big enough to do each side in one piece, but mine is much smaller than yours.

I glued mine to the original frame, only using nails around the edges - nothing in the centre of the sheets. After 10 years it has not moved.

Leigh.

[Roehm3108]

I'm going to go out of step a bit here.

WHen I looked into building my Cino Vardo, I looked extensively into which grade of plywood to use and spoke with the technical people at Austral Plywoods who manufacture all classes of plywood in Australia.

The bottom line is that you only need to use marine ply when what you are building is below the waterline. As long as the ply is what is called Type A bonded and preservative treated, it can be used for exterior building. The best for exterior structures is what is called Premium Structural and starts at 6.5mm thickness. It has a BB surface finish, which is very good for paint finishes. I used this grade for my walls, especially as the van is only single skinned. The added feature is that this ply comes in longer lengths of 2700mm by 1200mm.

I used a 4mm AC grade exterior plywood for the roof, because I did seal that on the outside with calico material and about 8 layers of paint!! The A side is the interior "seen" side.

In all, I am pretty confident Cino Vardo will outlive me and probably the next owners!