On Mon, 17 Apr 2006 01:41:02 GMT, "Moisés Nacio"
wrote:


rob wrote in message

Funny but I HAVE seen them covered on the outside and it's possible
that even those not covered might have had some covering / blockage
from inside (dunno because I can't see the attic of course). I agree
that if you don't care about cold air getting inside, then no need to
do anything. And usually moisture isn't a problem in winter for
unheated areas.

You are misinformed about moisture not being a problem in the winter. When
heat escapes from the thermal envelope into an attic, it must exit, or you
get condensation in the attic. It is simple physics of when cold meets
warm. Take for example a glass of ice cold liquid, sitting on a coffee
table at room temperature, it's not leaking fluid from the glass, but
sweats (condensation).

I have seen instances where homes had power vents and that's all. The
problem is, they don't come on in the winter. This caused thousands of

That's why the roof fan that I bought 23 years ago urged owners to
install a switch on the floor below, so they could turn the fan on
after a hot shower or something that put humidity in the attic. They
also urged people to install another switch to turn it off, when the
thermostat would turn it on.** They gave a wiring diagram, very
simple to use. I used one of those double switches on one box, but
mounted the box sideways, so the switches would be up and down.

**I use that in the early spring and the late fall to warm my house
with the daytime sun.

dollars worth of damage to the roof deck, insulation & wallboard.

Never block venting during the winter, unless you want condensation, rot,
and mildew.

This link will provide you a better explanation on how a house breathes.
http://www.airvent.com/professional/...s-iceDam.shtml