On Apr 4, 10:36 pm, Wayne Whitney wrote:
On 2007-04-04, Lawrence wrote:

Would it be silly to finish the back face without finishing the
tongue and groove?

IMHO is is silly to finish either the back side or the grooves. Just
install the flooring and finish it in place, that's the way.

I guess what I meant was, supposing I wish to go to the extra effort
of finishing the backside, is that useful by itself, or is it only
useful if I do all six faces?

It could be damp under there so if you are worried about it then it
definitely makes sense to use a vapor barrier between the finish floor
and the joists or subfloor.

This actually strikes me as a bad idea, as the floor deck should be
able to exchange water vapor through both faces.

Felt paper or paper especially for flooring are the usual products I
see in this application.

Right, those aren't vapor barriers.

Cheers, Wayne

Good luck and good bye.