Originally Posted by mecfd67
I have read many of these posts and have a quick comment question. When replacing the wood it seems no one ever uses a marine grade water proof plywood. Why would you not if you have it open already for accsess?
Marine grade plywood does not mean it is waterproof. It is made using douglas fir or western larch, which are more resistant to rot than pine, which is used in most plywoods. The plies are glued using a water resistant adhesive.
Louan is made using hardwood plies, birch or mahogany, which are also resistant to moisture and rot, as well as the waterproof adhesive used.
The stronger of the two for the same thickness and number of plies would be louan because of the use of hardwoods.
Marine grade plywood 1/4" x 4' x 8' made using birch or mahogany is around $100. per sheet, and is used mostly for boat building.
The same size louan is $12. per sheet.