LSMFT wrote:
Phisherman wrote:
On Fri, 19 Mar 2010 20:14:02 -0500, "Jerry
wrote:

Would it work to connect an exhaust fan in bathroom to the main stack
(cast
pipe)?



No. The main stack contains sewer gas, possibly explosive. Exhaust
the bath fan directly to the outside (not in a crawl space, not in an
attic space, not under a deck, etc)


Why not an attic space if it's vented??


That used to be SOP in the midwest, from when bathroom fans became
common, until maybe 20-30 years ago when people started sealing houses
more tightly. And in hindsight, it was a dumb idea. Even a well-vented
attic doesn't exchange the air (other than by convection) on still days,
so the chances to have excess humidity in attic (and condensation on
bottom of roof deck dripping down into the insulation) are pretty good.
Code, pretty much everywhere, requires external venting on new
construction, and it is a strongly recommended retrofit on older homes.
Trivial to do as part of a re-roof, and a good roofer will recommend it
as part of their review of the attic ventilation. (My guy said something
about the shingle warranty requiring the venting be up to standard, but
I don't know if that is true or not.)

--
aem sends...