I ve blogged about attic air.
Frost in attic melting.
How to prevent frost in the attic frost comes from air leaks.
Then the air condensates on the wood of the interior of your roof which is the coldest part of the attic.
The humid air in your home rises to the top of your home the attic when the temperature gets too low.
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This post is largely a re blog of my last post on attic frost but that was from 2013 and it s time for a reminder about all of this.
When a warm sunny day arrives after a long cold stretch and it seems like you have a roof leak when there isn t a cloud in the sky it s probably attic icing otherwise known as ice dams or ice damming and the surprising thing is that it s very unlikely that the roof covering itself is the problem.
When the outside temperature rises again the frost thaws water collects and can leak into your house.
House pressure affects.
It s rarely enough to cause a problem because the insulation sucks it up small quantities of water like a dry sponge.
While crawling in attics i often see a few drips here or there in the insulation where you can see evidence of minor frost melt.
The more humid a house is the more frost you ll find in the attic.
During winter conditions attic frost is a problem associated with attic bypasses.
If you ve ever experienced a leaky roof when it s not raining this is often the symptom of frost melting in the attic and this should be investigated before worrying about getting on the roof to examine seals and shingles.
When warm air from inside the house escapes traveling up through the bypasses the moisture condenses on the roof boards and rafters where the frost can form.
Frost itself doesn t do any damage but once it melts things get wet and then damage occurs.
Melting frost can lead to deteriorated roof sheathing.
Frost gets into the attic from air leaks or attic bypasses.
Why is there ice in my roof.
If the ventilation is working and the source of moisture has been eliminated the current frost and moisture will evaporate hopefully before it melts and drips.
More indoor humidity more frost in the attic.
Then it freezes against the wood and all of a sudden you have frost.