Heavy frost in attic

[ldapkus]

Originally Posted by mashburn

As it turns out, there was a leak around the flue pipe flashing. Appered ok form exterior and interior, well, the interior was so wet that it was very difficult to tell exactly where the leak was. Problem solved for now.

DUH!!!!

[ekartal6]

The insulation is upside down. The paper side always faces the conditioned space (the room where the heat is trying to escape from). When the paper is up, you trap moisture rising from the living space.

[ldapkus]

As it turns out, there was a leak around the flue pipe flashing. Appered ok form exterior and interior, well, the interior was so wet that it was very difficult to tell exactly where the leak was. Problem solved for now.

Thanks for the update.

[Mario A. Kyriacou, CHI]

WOW!!

NACHI members helping NACHI members at it's finest!!!!

Good find Michael!!

[Brian A. MacNeish]

Originally Posted by mashburn

As it turns out, there was a leak around the flue pipe flashing. Appered ok form exterior and interior, well, the interior was so wet that it was very difficult to tell exactly where the leak was. Problem solved for now.

Have seen the phenomenon in the pictures too many times to the point that the north facing roof sheathing rotted out over time while the south facing was still OK due to drying from the sun!!

Too much frost on the roof sheathing to be from a leak only!! The house needs an interior ventilation and moisture assessment........why the high rh's???

Take care of the interior moisture first and then airseal the ceiling from the attic at all penetrations (wiring, lighting, plumbing, chimney, attic hatch, tops of partition walls, pot lights [be careful here if there are any], any other air leaks). This is an energy saver as it stops warm air from leaving the dwelling uncontrolled as well as reducing/stopping moisture from leaving the house via the attic....fans should be doing this!!

See:
RE-EXAMINING ROOF VENTILATION

The world of the roofer is changing quickly. Only a year or so ago, customers blamed the roofer for ice damming and wet-attic problems. The solution was simply to add attic ventilation, in many cases beyond building code requirements. Why? Because it was the roofer's only choice. In order to provide the homeowner with a full manufacturer's warranty, ventilation had to be installed according to the requirements of the local building code: typically 1 ft2 of ventilation for every 300 ft2 of insulated attic space, and twice that amount for low-slope roofs. Unknowingly, the roofing industry was making the wet-attic situation worse. How? They were following the correct procedure for ventilation, but solving only part of the problem instead of the whole problem. Ventilating a previously unventilated attic has the effect of making the attic colder. If nothing is done to stop warm, moist air from entering the attic space from the living space, condensation on the now-cooler surfaces is a certainty. Mold, mildew, and eventually leakage into the living space will probably follow.

Insulation contractors, armed with the same lack of information about attics as the roofers, have caused similar problems. Insulating the attic floor makes the attic colder in the same way as adding ventilation. But, if contractors don't seal as well as insulate, they don't stop warm, moist air from entering the attic and causing big problems.

Now, thanks to public debate, reeducation, and the publication of Attic Venting, Moisture and Ice Dams, a report by Canada Mortgage and Housing Corporation (CMHC), roofers know much more about what's happening, why, and what to do about it.

For the rest of the article, see:
http://homeenergy.org/archive/hem.di...00/001110.html


For the CMHC article, see:
https://www03.cmhc-schl.gc.ca/b2c/b2c/init.do?language=en&shop=Z01EN&areaID=0000000026&p roductID=00000000260000000011