I went to an Arizona Building Officials conference a couple of weeks ago and they said all disconnects should be sealed on three sides. (the top and both sides) The bottom is left open in case water gets behind the disconnect it then has a way to drain out. I asked them if they called it out as a defect and they said "yes".

However, I have never seen it done in the Phoenix area. I guess we just don't get enough rain to worry about those minor things.

When I get a chance, I'll see what I can find in the code book.

Jeff Euriech
Peoria, Arizona