We were up checking the cottage out on the weekend. The south side of the roof has no snow on it and the ridge vent is clear the north side has a bit of snow on it. Dh went up to check the attic and notice that there was frost inside on the truss only on the north side . We have plywood, Ice watershield on the entire roof then fibreglass shingles. inside we have had the celing blown with insulation.
Is this common to have frost or have we done something wrong.
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Replies
Sounds normal to me.
soffit vents?
vent channels to let them breath above the cellulose?
As I recall, this is new this year.
Is it heated yet? Moisture sources?
Is it all finished or are there ways for moisture to penetrat to the attice space yet unfinished?
Did you notice the frost first thing or after being there fort the weekend?
A new house will make excessive moisture for the first year or so as materials dry out and stabilize.
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PoorGirl,
The frost is probably seasonal and unlikely to damage your attic.
But it is a sign that your ceiling has not been air-sealed. Warm, humid interior air is entering your attic through ceiling leaks, and condensation is occurring on the cold surfaces in your attic.
The solution is to get an air-sealing contractor or home-performance contractor (someone who knows what he or she is doing) to go up un your attic with some spray foam and seal the leaks under the insulation. Typical problem areas include plumbing penetrations, wiring penetrations, recessed can lights, chimney chases, and attic access hatches without weatherstripping.
Poor girl ... 2 weeks ago we all had 3 feet of snow on our roofs and more than likely your ridge vents were at least 2 feet under. The warm conditions and rain cleared them last week. I think it's just residual humidity that was unable to escape while the ridge vent was covered. I'm not a big fan of ice and water over the entire roof 'cause it makes things too tight, so all thngs said there shouldn't be frost, check the soffit venting is clear, baffles as required and consider some maxi vents on the roof where the snow is not so deep .. or, visit the cottage more often to clear around the vents ..
where the cottage?, Ontario boy.
Wane you are right about the snow dump, I think we will have to wait and see and check it again next time we are up. The enitre cottage is not yet vapour barriered so this might be some of the problem.
We have 2 4800watt construction heaters going full time in the basement to keep it dry and to continue to dry the basement out so there is moisure in the air coming from the basement.
We just wanted to make sure that it wasn't a huge problem.
The baffles were put in place, the soffits have air space and we haven't started on the interior yet. we only finished the vapour barrier before we shut down for the season.
Once again thanks for your help everyone.
It's almost certainly not a leaky roof. Moisture in the attic air is freezing on the cold roof. It may be that your ceiling is leaking a lot of air into the attic, or air could be being drawn into the attic from a bathroom vent fan or high-efficiency furnace flue that's too close to the soffit vents. (Or a bathroom fan could be vented directly into the attic.)
Thanks Dan H, no we know it's not a leaky roof, the bathroom fan is vented out side but as I advised earlier, we do not have all the vapour barrier up, so this could be it.
thanks for trying to help.
Dan,
Is that your letter in this months JLC magazine ?
Walter
Are there any heat ducts in your attic? A lot of cottages seem to have heat ducts run in the attics with a small amount of insulation over them and this will lead to big problems!!
I doubt it.
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Assuming you're not in TO (where 6" of snow is cause for calling out the Army), you need to know that ridge vents don't work in our climate. The frost you're seeing is likely condensation, the result of the snow-pack (now washed off by the rains two weeks ago) blocking cold air flow through the attic space.
Install a 'Charley-Noble'-type wind-powered turbine up there; one turbine for each 450SF of attic oughta do it.
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