Personally I would pre-finish everything. In the event of contraction you don't want to see the tongue unfinshed. And any bordering pieces such as 1x's you wouldn't want to see any non-stained parts from contraction on that either.
Unless it's in a screened porch, or in an area where water may come in contact, I would not bother with the back. Otherwise pre-cut and finish all 6 sides. As far as material we use Sherwin Williams products.
Unless it's in a screened porch, or in an area where water may come in contact, I would not bother with the back. Otherwise pre-cut and finish all 6 sides. As far as material we use Sherwin Williams products.