In the parlance of building scientists these cold wooden house parts make up a condensing surface much like a cold glass of ice tea beads with water on a hot summer day.
Causes of frost in attic.
Frost is caused by moisture that escapes up through attic bypasses then condensing on the roof boards and rafters.
If it s due to air infiltration from the living space then air sealing should be the first thing you do not the last.
Frost comes from air leaks.
You definitely don t want frost is your attic.
Water vapor is migrating upward and eventually filtering into the attic.
It is caused by a poor understanding of building science.
Frost gets into the attic from air leaks or attic bypasses.
This frost is the result of warm air rising from the living areas underneath.
Therefore my suggestion is that if one finds frost in the attic one first has to identify which of the three causes is contributing to the problem.
You definitely don t want frost in your attic.
Many in the building technologies sector feel vapor retarders are great in wall cavities but should be avoided in most ceilings.
Warm air bypasses gaps cracks holes where warm air is allowed to enter the attic space from below electrical plumbing wall plates etc.
Attic rain is caused by the rapid melting of excessive frost in the attic or walls.
Not only is it difficult to do but it might also create hidden problems.
What causes frost in your attic.
The humid air in your home rises to the top of your home the attic when the temperature gets too low.
When it reaches the cold surface of the roof sheathing and framing it turns to frost.
Without proper attic ventilation in your home you could have a considerable amount of frost accumulate in your attic during the cold winter months.
Melting frost can lead to deteriorated roof sheathing mold on the roof sheathing wet insulation and water stains on the ceilings.
Well temperature fluctuations like that are a prime culprit for frost in the attic.
In no particular order here are some common causes of frost build up in the attic space.
Remember that polar vortex we had not too long ago where we had 70 degree temperature swings in about 48 hours.
If cold attic air somehow makes it way through a weak spot in the insulation it may cause water to condense on the underside of the vapor retarder.