# Snow getting in through soffits and onto drywall ceiling



## pwm (Jan 19, 2012)

Hi all. I’ve had a problem since our house was built which is that the drywall in the attached garage ceiling has been getting wet every spring. I believe it is from snow blowing in through the soffits and getting on the vapour barrier. Then when it melts, it spreads over the plastic and soaks into the drywall. The soffits are aluminum and have holes in them for ventilation. That’s my theory at least. Some pieces fell off this spring and I’ve pulled down some more drywall which was wet and soft. I know the soffits are supposed to allow air to pass through them for ventilation, but what can be done to prevent snow from getting into the area above the drywall? It's completely open to the soffits. Not sure what the solution would be. Back in the day, soffits were just plywood and were sealed with calking. The facia is over 12' high facing north and we get some high winds during winter here in Manitoba. The roof sheeting is good and shingles were replaced last year and were not in bad condition before replacement. It's not water getting in from above for sure. Closing off the area from the soffits would work, but it would defeat the purpose of the ventilation of the rafter area above the ceiling.

Any ideas?


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## Eder (Feb 16, 2011)

I would check that condensation escaping due to lack of insulation may be causing ice on underside of roof sheathing. If you have access to the attic space see if the ceiling insulation extends completely over the top plate of the wall frame.
Barring that, non vented soffit to match your vented is available & easily swapped out.


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## like_to_retire (Oct 9, 2016)

What about installing insulation foam baffles. These are designed to allow air to still pass up between the rafters, but they stop insulation from blocking the air.

They might work to block snow.

ltr


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## OnlyMyOpinion (Sep 1, 2013)

As Eder suggests, it could also be condensation. If it is snow coming in the north-facing soffit then you may not have sufficient baffles which should prevent the blow in.
I would not close off the soffit venting though. Doing so could allow excessive attic heat and/or trapped moisture. 
In either case, a good vapour barrier should prevent the ceiling drywall from being damp. Where specifically is the drywall wet? (i.e. between joists along north side, along joists, etc.)


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## Eder (Feb 16, 2011)

Ya we used these when we used blown in insulation to prevent spilling into the soffit space...leaving a 2" min space between the top of the insulation stop to the sheathing. Hopefully that solves your problem as reducing free air ventilation in any attic is a poor idea.


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## cainvest (May 1, 2013)

Is your roof sheeting extending out over the fascia board and/or do you have drip edges installed?

Just a thought, as I've seen this before, is water is getting behind the fascia board and on top the soffit draining back towards the house.


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## pwm (Jan 19, 2012)

Thanks for the replies. There is no insulation in the garage, either the walls or the ceiling. There is a vapour barrier stapled onto the roof trusses and drywall screwed on over that. The drywall is/was wet mostly on the north side. I actually know for sure that snow has gotten in because a few years ago a piece fell off and I looked in there before replacing it early in the spring and I saw snow. 
Questions: 
o Why even bother having any drywall on the ceiling at all? When I built my shed I used the same Kaycan aluminum facia and soffits as the house and it's just open above the roof trusses up to the roof sheeting. Why not do the same in the garage? Why have drywall ceiling?
o BTW, I've never seen any snow get in the shed through the soffits, maybe because it's only 8' high and partly sheltered by the house.
o Why am I the only house in this area with this problem when they were all built at the same time with same soffits?

(Rhetorical questions I suppose)


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## like_to_retire (Oct 9, 2016)

pwm said:


> Why have drywall ceiling?


Aesthetics.

ltr


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## OnlyMyOpinion (Sep 1, 2013)

If its not insulated, there are probably no baffles in place either.



pwm said:


> Why even bother having any drywall on the ceiling at all?


No good reason as described. Probably a bit warmer though than if warm air was free to move up to the roof?
Helps keep soffit snow off the car? :hororr:


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## pwm (Jan 19, 2012)

Thanks again for the replies. I wasn't sure what was meant by baffles. I just got back from a walk through an area of new house construction and went into a house which did not have garage doors yet and the roof trusses are still open to the roof sheeting. I know, I was trespassing but no harm done right? Now I know what you are referring to by baffles. I drove back with my camera and I'll attach some photos I took. The soffits are sealed from the top plate to the sheeting, except for certain places which have a cover that extends up about 90cm. It appears to be some kind of cardboard material. This may be exactly what I need. My soffits are the same as my shed which means they are completely open to the space above the drywall ceiling. Is this what you meant by baffles OMO? 
Photos are too large. I'll post them in the next message after I make them suitably smaller.


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## AltaRed (Jun 8, 2009)

I had a similar problem in a Calgary home on the east wall/vaulted ceiling of our 2 storey dining room in the late '80s. In the Spring, I would see wetness about 6-12 inches in from the wall on the ceiling and down about the same length on the wall itself. Location varied slightly in the 2 spring seasons that it occurred. What had happened was ice buildup on the roof over the soffit area. The sun in the morning would melt snow on the roof and then it would freeze once the sun intensity was gone and water would back up underneath the shingles.

I installed heating cable in a zig zag along that section of roof line and the problem never happened again. Like this... https://www.rona.ca/en/roof-deicing-cable-0356022--1

I personally don't think it is snow getting up through the holes in the aluminum soffits.


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## pwm (Jan 19, 2012)

Let's try this: 















Worked well at 1920X1080. Are these the baffles you were referring to?


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## hboy54 (Sep 16, 2016)

AltaRed said:


> I personally don't think it is snow getting up through the holes in the aluminum soffits.


I don't believe it us snow either.

Chasing leaks in roofs and boats is a highly frustrating activity. Good luck with it.


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## Eder (Feb 16, 2011)

Well that looks like structural sheathing over the ends of the trusses to prevent buckling as they are high heeled....you would want a space between the roof sheathing & the top of the insulation...since you lack insulation you should at least have a row of blocking between trusses. Drywall is pretty useless in a garage other than the fire separation between house & garage.
Are you sure the snow you saw wasn't white frosty ice build up?


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## like_to_retire (Oct 9, 2016)

pwm said:


> Let's try this:
> 
> View attachment 19374
> View attachment 19376
> ...


No, they are foam baffles as seen in the attached picture. Buy at any Home Depot.

The top is stapled to hold it in place and the bottom sits on the top plate of the wall.

You can see that there is no way snow can enter from the soffit, yet air passes up the two channels.









ltr


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## pwm (Jan 19, 2012)

like_to_retire said:


> No, they are foam baffles as seen in the attached picture. Buy at any Home Depot.
> 
> The top is stapled to hold it in place and the bottom sits on the top plate of the wall.
> 
> ...


Excellent, Thank you LTR. They are somewhat similar to what they did in the photos, but these appear to be a simpler solution. I know for a fact that snow can get in through the soffits because my daughter's garage has the same construction as mine except there is no vapour barrier and drywall around the perimeter of the garage. It's a "cab over" so the centre section is finished, and insulated because there's a bedroom above it, but the perimeter is not and she gets piles of snow on the workbench and other areas which would be on top of drywall if it were there. Now I see why they built her place the way they did. Either get snow in the garage, or on the drywall. Pick your poison. I can see why someone invented the baffles that LTR has pointed out.

Thanks again LTR.


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## Gumball (Dec 22, 2011)

sound like you have whats called an "Ice Dam" check it out on youtube there are some videos how to prevent it, etc...


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## OhGreatGuru (May 24, 2009)

pwm said:


> Thanks for the replies. There is no insulation in the garage, either the walls or the ceiling. There is a vapour barrier stapled onto the roof trusses and drywall screwed on over that. The drywall is/was wet mostly on the north side. ...


I'm kind of surprised there is no insulation whatsoever. Even my 50-year old house had R12 (or maybe R10) batts in the ceiling of the attached garage. If there is no insulation, that would explain why you have no baffles. The baffles just prevent insulation from blocking the air flow from the soffit vents. They would have the added benefit of slowing down any strong wind that might be carrying in snow. But as others have suggested it's pretty iffy whether you really have snow infiltration versus frost buildup from moisture migrating into the attic. Let's see - Manitoba: lots of wind; generally dry snow. It's theoretically possible that you have so much ventilation that a good wind will carry snow in. But that's pretty rare with soffit vents. More of a problem with gable end louvres.

Have you got roof-top vents that might be letting in snow under the right conditions?


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## pwm (Jan 19, 2012)

OhGreatGuru said:


> I'm kind of surprised there is no insulation whatsoever. Even my 50-year old house had R12 (or maybe R10) batts in the ceiling of the attached garage.


Why insulate an unheated building? What would be the point?


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## lonewolf :) (Sep 13, 2016)

pwm said:


> Why insulate an unheated building? What would be the point?


Heat coming from the ground would keep an attached insulated garage a lot warmer then the temp outside on cold days. Have a 3 stall attached garage & can have several weeks of -30 to -45 & the temp rarely gets below freezing inside the garage. Can turn the heat on in garage but never do as the ground keeps the temp warm enough


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## like_to_retire (Oct 9, 2016)

pwm said:


> Why insulate an unheated building? What would be the point?


No reason to insulate or even have drywall in the ceiling if you will never be heating the area. I think the problem comes when someone decides they'll introduce some heat for some reason such as working on a project or their car. This heat rises and condenses on the roof sheeting and can create frost that can melt and soak the sheeting or drip down. The only way around this is to add plastic vapor barrier and drywall and insulation. Of course you also need soffit baffles, so it isn't the worst thing if you already have baffles installed to keep snow out.

ltr


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## cainvest (May 1, 2013)

lonewolf :) said:


> Heat coming from the ground would keep an attached insulated garage a lot warmer then the temp outside on cold days. Have a 3 stall attached garage & can have several weeks of -30 to -45 & the temp rarely gets below freezing inside the garage. Can turn the heat on in garage but never do as the ground keeps the temp warm enough


^^ This

Makes a pretty big difference.


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## Prairie Guy (Oct 30, 2018)

pwm said:


> o Why even bother having any drywall on the ceiling at all? When I built my shed I used the same Kaycan aluminum facia and soffits as the house and it's just open above the roof trusses up to the roof sheeting. Why not do the same in the garage? Why have drywall ceiling?


If the garage is attached to the house, then drywall would be required by code in most places as it provides a seal against exhaust gas from entering the house. In most cases the drywall must have a coat of mud as an additional sealer.


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## Prairie Guy (Oct 30, 2018)

lonewolf :) said:


> Heat coming from the ground would keep an attached insulated garage a lot warmer then the temp outside on cold days. Have a 3 stall attached garage & can have several weeks of -30 to -45 & the temp rarely gets below freezing inside the garage. Can turn the heat on in garage but never do as the ground keeps the temp warm enough


Some have suggested, and I don't know if it's true, that repeated freeze/thaw cycles may encourage premature rusting of vehicles as the constant melting allows melted snow containing road salt to find its way into vehicle crevices more easily. It also provides several hours per day of warmer temps where the corrosiveness of the salt will be more active.


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## like_to_retire (Oct 9, 2016)

Prairie Guy said:


> Some have suggested, and I don't know if it's true, that repeated freeze/thaw cycles may encourage premature rusting of vehicles as the constant melting allows melted snow containing road salt to find its way into vehicle crevices more easily. It also provides several hours per day of warmer temps where the corrosiveness of the salt will be more active.


Nothing worse than keeping a car in a heated garage every night in the winter. Perfect conditions that encourages rust.

ltr


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## nobleea (Oct 11, 2013)

Prairie Guy said:


> If the garage is attached to the house, then drywall would be required by code in most places as it provides a seal against exhaust gas from entering the house. In most cases the drywall must have a coat of mud as an additional sealer.


Drywall is also required in this case for fire separation. Type X drywall (fire rated) is usually required between an attached garage and living spaces (beside or above the garage).


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## Prairie Guy (Oct 30, 2018)

nobleea said:


> Drywall is also required in this case for fire separation. Type X drywall (fire rated) is usually required between an attached garage and living spaces (beside or above the garage).


Yes, I missed putting that in my reply.


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## cainvest (May 1, 2013)

Prairie Guy said:


> Some have suggested, and I don't know if it's true, that repeated freeze/thaw cycles may encourage premature rusting of vehicles as the constant melting allows melted snow containing road salt to find its way into vehicle crevices more easily. It also provides several hours per day of warmer temps where the corrosiveness of the salt will be more active.


As someone who's been keeping their vehicles in an insulated but unheated garage for over 30 years I'll call BS on it causing extra rust.


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## like_to_retire (Oct 9, 2016)

cainvest said:


> As someone who's been keeping their vehicles in an insulated but unheated garage for over 30 years I'll call BS on it causing extra rust.


I think it's in a heated garage that the problem occurs.

ltr


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## OhGreatGuru (May 24, 2009)

If it is an attached garage, insulation will reduce the heat loss from the adjoining wall, though not so much as it used to if the wall insulation is R20. Remember OP lives in Manitoba, where it can get pretty darn cold. By insulating the garage, the interior garage temperature will gain some from the heat loss from the house; more if you have a block heater plugged in. It won't be above freezing, but better then outdoor temperature. Might make for easier starts when it is -30C outside.

I know blowing snow migration can be a problem in NWT and other northern areas. PWC used to design various hoods over different vents to try to prevent this. Hadn't heard it was much of a problem further south.

Attic ventilation has to be a compromise in our climate. In summer you want a lot of it, to keep attic temperature down, and reduce cooling load. But in winter you want just enough to prevent condensation/frost build up. Ideally we would have vent areas that could be changed seasonally, but that would be too much of a maintenance hassle for most people.


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## pwm (Jan 19, 2012)

It was -40 several times this year. Centigrade or Fahrenheit, same thing. It's where the two scales cross. Windchill was way below -50, but that's for Eastern pussies. I only go by the actual temp and still walk twice every day regardless. It just takes longer to get dressed is all. 

As for heated garages, here in Manitoba your car will rust to pieces before your eyes in a heated garage. The condensation will kill it. I have a colleague who has a V12 Jaguar collector car stored in an insulated garage which he heats from time to time, and he has it sealed in a huge plastic bag. I'm not making this up, I've seen it.


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