Basements, Attics and Crawl Spaces - Novice townhomeower - ice/frost in the attic
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SparkyGirl
12-16-08, 07:11 AM
Peeked up into the attic just to check on things, and noticed that at least half of the roofing nails have ice on them, and the plywood is full of frost.
This is my 2nd winter in this townhouse. Last winter I did not have this problem.
Two things have occurred since last winter:
1) I had a whole house humidifier installed
2) The association had a new roof, gutters, and soffit put on. (I believe there are just two "gable" vents up there. I really can't get up into the attic other than peeking my head in.)
I did some reading about ventilation, insullation, etc..... and just got really confused as to what I should be doing first.
Could just use some help with troubleshooting why this is happening, and what I can do to help prevent mildew. Thanks so much for any suggestions!
Juliet
This is my 2nd winter in this townhouse. Last winter I did not have this problem.
Two things have occurred since last winter:
1) I had a whole house humidifier installed
2) The association had a new roof, gutters, and soffit put on. (I believe there are just two "gable" vents up there. I really can't get up into the attic other than peeking my head in.)
I did some reading about ventilation, insullation, etc..... and just got really confused as to what I should be doing first.
Could just use some help with troubleshooting why this is happening, and what I can do to help prevent mildew. Thanks so much for any suggestions!
Juliet
twelvepole
12-16-08, 08:26 AM
Sounds like a lack of attic ventilation and a problem with warm, humid air escaping from heated area below into attic space and condensing and freezing. Seal all gaps around perimeter, pipes, vents, etc. Make sure you have adequate attic ventilation and insulation. Rule of thumb, is one square ft. of vent opening needed for every 150 square ft. of ceiling. All vents should be vented to outdoors and not into attic space.
Q Brizzle
12-16-08, 08:29 AM
It's pretty simple, really. You have warm, moist air escaping your living space into the attic. The nails are especially cold, so they condense the moisture first, forming the icicles.
The plywood decking is also very cold, and the moisture turns to frost quickly on this surface.
Things to check:
1. Is the insulation sufficient and evenly distributed?
2. Are any air intrusions into the attic well-sealed and vented to the exterior?
- this includes bathroom fans, kitchen exhausts, sewer vent stacks, etc..
3. Is the relative humidity in the house very high? With temps around zero in the Chicago area (I'm in southern WI, so I know it's quite cold right now), your indoor RH should ideally be around 30%. 40-50% or more in these temps will cause a lot of condensing of moisture.
The plywood decking is also very cold, and the moisture turns to frost quickly on this surface.
Things to check:
1. Is the insulation sufficient and evenly distributed?
2. Are any air intrusions into the attic well-sealed and vented to the exterior?
- this includes bathroom fans, kitchen exhausts, sewer vent stacks, etc..
3. Is the relative humidity in the house very high? With temps around zero in the Chicago area (I'm in southern WI, so I know it's quite cold right now), your indoor RH should ideally be around 30%. 40-50% or more in these temps will cause a lot of condensing of moisture.
Gunguy45
12-16-08, 08:36 AM
Hey TP...I thought it was 1 SF free area (minimum) for every 300 SF of attic? Evenly divided btwn intake and exhaust? 1/300 rule? I know more won't hurt. Or have they upgraded the Rule of Thumb...lol
Just wondering....
Just wondering....
robertrobillard
12-16-08, 08:46 AM
Juliet,
Q Brizzle is 110 percent correct. You should also check for air leaks into the attic.
Warm air leaks into the attic through penetrations.
Q Brizzle is 110 percent correct. You should also check for air leaks into the attic.
Warm air leaks into the attic through penetrations.