NathanL wrote:The good news is you really don't need it. There are several species that can be marine plywood. Douglas fir - which is nice and the cheapest but the faces have a tendency to check if you only paint them and not glass them. Sepale is really nice but more expensive and can be more decorative. Meranti is another choice, which is probably half way between douglas fir and Sepale in price and availablity. Sometimes referred to as mahogony plywood. One brand is hydrotek.
Like everyone has said marine plywood normally has no voids in the inner plys, an A face on the outside (You can get marine play in AA, AB, and AC) with AB what you find more often, and glued with a water resistant glue. Good marine ply will normally have a higher ply count as well. Instead of say 5 plies in an exterior AC grade the same thickness of marine ply can/will often have 7 plies.
Marine plywood in a lot of sizes will come in oversize sheets (more $$) of up to 5'x10' in a single sheet or up to 5'x24' in pre scarfed sections in 2' multiples.
Another option if you are going to paint is MDO (Medium Density Overlay) which is a high quality plywood with an exterior glue, limited voids, and a resin impregnated paper face on one or both faces. Stuff is wonderful for outside exposure and it's normal use is outdoor signs. Even without painting the faces will last a long time in heavy exposure. The resin impregnated paper face is ready to paint and takes paint well and no chance of checking etc....Don't confuse it with MDF. It also can be bought in oversize sheets up to 5'x10'.
Thank you NathanL, Now I have a question... whats "checking"?
The price I saw was for the Douglas Fir, $96 for 3/8" the Sepele was higher. I definatly plan on useing red cedar for the floor. Its a wee bit heavy but very rot resistant with the bottom side being tarred. For the roof Im leaning towards useing the paulownia again, I got a nice easy way of doing the curved roof with the tongue and groove (working mostly alone it would also be easier to do a board at a time then luggin a 5x10 sheet of wood) and then covering it with EPDM... might go with white this time.
For the side walls depending on the axle I put on it how much width I can get away with. I thought useing a "plywood" wall I can go thinner then the 3/4" paulownia and be able to frame the wall and then put up a complete wall on the trailer. If I do the paulownia tounge and groove on the walls this time Im going to glue it and use the nail gun to tack the boards in place then when the whole wall is in place screw them into the supporting 1x2's... hopefully will be a little faster build time.
I do have about 3/4 of a gallon of a thinned epoxy so if I go the plywood route I can apply it. I might do the ends of the paulownia since this time Im going to be useing it vertically not horizontally so I figure it cant hurt to encapsulate the ends.
thanks
deryk
