Less to be certain. But just the air by itself carries a lot more water
vapor than can dissipate in cold air, and a fan will draw air from outside
the half-bath. It still will be moisture-laden air and that moisture will
collect on the insulation. Not as much or as fast, but it will affect the R
value to some extent. Best it goes outside in the winter (whenever
possible).


"Goedjn" wrote in message
...

only against code, it's also more expensive to heat the home. Bath (and
kitchen) fans carry a tremendous amount of moisture. Dump this into the
attic in cool/cold weather will cause this moisture to settle into the

It occurs to me that this isn't necessarily true of half-baths,
though.