Attic Frost

This is an example of air leakage into an attic in a cold climate. In this example there is a false wall that was never air sealed between the conditioned space and the attic, resulting in considerable air leakage and hence humidity into the attic, which when it warms rapidly will mealt and result in
1. wet ceiling drywall and water drippping in windows and
2. coffee coloured stains on the exterior siding

Category:

Education

Tags:

• Attic frost
• Condensation
• air leakage
• building envelope

[qualistat]

The issue was an opening in the ceiling - a 2" by 5' space between the plumbing wall in front of the exterior wall was allowing humid air to leak into the attic. The temperature over the previous 3 days was -28 C and the clear sky was causing the attic to be closer to -32. Combined with a mechanical system that was pressurizing the house.

[matt0390]

Did you guys find out why it was frosting up in that spot? was it from how the insulation was installed? Thanks Matt.