Frost on inside of attic sheathing

[Peter C. Russell]

Originally Posted by lrollins

All this talk of proper insulation and stopping moisture infiltration into the attic..... Proper insulation is important but has nothing to do with this problem. It is important that the insulation does not have a vapor barrier however, especially in ceilings and attics.
More importantly, you can not, and should not, stop moisture infiltration into the attic. Moisture is generated in a home every day... all winter. This moisture has to go somewhere, or the home will become laden with moisture. I remember the 70's when polyethelene plastic was recommended to cover the complete exterior of homes. This was done to stop air infiltration. Instead it stopped moisture from moving thru the walls and ceilings to escape. I have drilled the sheetrock at the bottoms of walls in these homes only to have gallons of water drain out of the wall cavities. Moisture is coming into the home from somewhere (cooking, showering, crawlspace, etc.) Allow it to naturally move to the attic and then insure proper ventilation. If it is coming from the crawlspace you can help by insuring a good ground vapor barrier.

Actually in NH we move moisture laden air by mechanical means to the exterior of the home. Along with air sealing you must get that moisture from kitchen and baths out of the house.
If you have moisture in the attic, it got there by air movement, therefore, in my area, you have not installed the insulation correctly or you may have other air sealing issue's

[Larry F. Rollins]

Good Point David. By the way, I originally come from Freedom, New Hampshire in the Mt. Washington Valley. The Mount holds the record for the highest windspeed ever recorded on earth... I believe it is 232 mph. Tuckerman's ravine on the mount has recieved over 200 feet of snow in a winter. They ski into August there. I'd say that's in the running for most hostile weather in the entire United States.

[David A. Andersen]

-47F is not the lowest temp in the lower 48, but add 231mph and you have one heck of a wind chill!

[Peter C. Russell]

Originally Posted by dandersen

-47F is not the lowest temp in the lower 48, but add 231mph and you have one heck of a wind chill!

Today we are going to have high temperatures in the mid 20s with 15-20 mph winds.

Good recipe for wind washing in a drafty home.