Use the pressure treated stuff, and add your own additional treatment to ALL cut surfaces.........This works GREAT. Also, make sure you pre-drill any holes, and swab with treatment. Don't use Thomsons, or the other watery type sealants......Use BAER, or something better.

This will GUARANTEE waterproofness for MANY, MANY years. I have refloored some boats, and rebuilt some jon boats using that method.

Later,

Geo