by doug hodder » Sat Jul 30, 2011 1:29 pm
It kinda depends on your budget. Marine grade ply is wonderful stuff, but in my opinion, isn't necessary. It's pricey. I only use the thin marine stuff to skin over regular ply on a woody as I buy the mahogany stuff.
Baltic birch is great as well, but only comes in typically 5x5 sheets, so it needs to be joined. It paints up great and has tons of laminates in it so it is really stable. It's made for cabinet construction. I use a lot of it in my builds available at regular type "lumber" yards, not a big box item. It's also more expensive
Another option is MDO. It is a sign industry type ply, made for exterior uses and can be had with 1 or 2 sided laminate that takes paint great. I've used it with good results. They don't sell a lot of it so it's usually really dry. It's not sold at big box stores. Gotta go find it.
I know that Bob Henry has used OSB on his builds with decent results. I haven't done that so can't really be of help there.
Watch any "green" ply as it will want to do strange things as the moisture content drops. You might find yourself fighting warped ply and that's a real drag around the door areas. I do use it for my floor. I've done tears using the big box ply for sides, but laminated a nice birch skin for the interior and either skin in aluminum, or do epoxy and paint on the exterior.
On any of your ply, don't leave it sitting against a garage wall for storage as it will want to cup. Try to leave it flat until you get it cut into smaller pieces. If you have to leave it vertical, try to clamp it to something so that it doesn't do that. Once you cut your doors, lay them flat for sure, don't lean them. Ask me how I know this.....
I'd imagine that you'd only have outgassing problems on something like an OSB/ particle board/ MDF situation, but I'm no expert on that.
Just my opinions. Doug