Frost / water on garage walls - desperate for a solution

[pmjski]

Hi, I'm new here and this is my first post as we have a major issue with our garage and I am at a loss as to how to proceed without tearing the whole thing down and rebuilding which we can't afford.

Some background - we live in a cold climate in Canada and we bought our 1974 house last year and it has a double detached garage. The garage is uninsulated, not heated, exposed OSB and this winter/spring we noticed significant frost and subsequently water once it got warmer on all of the OSB walls and roof. Everything was just soaking wet. I've attached photos. You can see the exposed siding/roofing nails had a thick buildup of frost on them. The garage is uninsulated which is fine, we know others with uninsulated garages here just like ours and they do not experience this issue. I know parking the car with snow on it and snow melting in the garage can cause this, but we tried parking in the driveway for a while and the issue still occured.

The garage has no soffits / vents, but has no enclosed roof. Would adding some venting/ perforated soffit help with this? Once we noticed the issue we started leaving the man door open 24/7, which seemed to resolve the issue, but is not a permanent solution for obvious reasons.

We are desperate for some answers here before next winter, if anyone knows why this might be happening or can offer some advice/potential solutions it would be greatly appreciated.

Thank you

 

[Badhabit]

You could try vents. The humidity is way to high in the garage. Maybe even put in a fan to get some air moving thru there. Just remember that my advice and a couple of bucks will get you a cup of coffee

H

 

[Bondo]

Would adding some venting/ perforated soffit help with this?

Ayuh,.... Moving more air around will help, however you care to do it,....

 

[acer66]

Might be apples to oranges since it is a metal garage in climate zone 7.

My buddies metal garage with no insulation, inside walls or ceiling was a rain forest due to condensation when temps changed even just in the am.

A proper sized fan on one end and a vent cut in on the other aide took care of that.

Welcome to the site and I am sure you will figure this out pmjski.

 

[Rst277]

Hi, I'm new here and this is my first post as we have a major issue with our garage and I am at a loss as to how to proceed without tearing the whole thing down and rebuilding which we can't afford.

Some background - we live in a cold climate in Canada and we bought our 1974 house last year and it has a double detached garage. The garage is uninsulated, not heated, exposed OSB and this winter/spring we noticed significant frost and subsequently water once it got warmer on all of the OSB walls and roof. Everything was just soaking wet. I've attached photos. You can see the exposed siding/roofing nails had a thick buildup of frost on them. The garage is uninsulated which is fine, we know others with uninsulated garages here just like ours and they do not experience this issue. I know parking the car with snow on it and snow melting in the garage can cause this, but we tried parking in the driveway for a while and the issue still occured.

The garage has no soffits / vents, but has no enclosed roof. Would adding some venting/ perforated soffit help with this? Once we noticed the issue we started leaving the man door open 24/7, which seemed to resolve the issue, but is not a permanent solution for obvious reasons.

We are desperate for some answers here before next winter, if anyone knows why this might be happening or can offer some advice/potential solutions it would be greatly appreciated.

Thank you

Yes, you need airflow for a building to work properly. You could try some gable end vents or a turbine style vent on the roof. There is nothing wrong with the garage itself, it just needs to breathe.

 

[DGersic]

No pictures.

I’d be most curious what the source of the moisture is. Is it just humid air and a cold surface? Or is it ground moisture coming up through the (concrete?) floor? I wouldn’t expect a lot of humidity in the air in a Canadian winter.

I have a detached, unheated garage, and I get some humidity around the spring when the concrete floor is still cold and the air moisture rises, but not dripping wet. I do have foam board insulation, which slows down the change in temperature inside, but not greatly.

 

[CraigStu]

Have I missed something? I see no pictures so had no idea it is a metal garage as someone mentioned.

 

[rooster59]

I would guess the moisture increases during the day, evening. Air is a bit warmer, cars come in wet, snowy, etc. When the temp drops at night air passes through dew point, moisture condenses. You need to vent it. I had a high roofed metal barn, it would actually rain inside if the temp outside dropped. Roof vent and gable vent, no more rain. Or insulate walls, add insulated ceiling, vent the attic.

 

[Hohn]

Hi, I'm new here and this is my first post as we have a major issue with our garage and I am at a loss as to how to proceed without tearing the whole thing down and rebuilding which we can't afford.

Some background - we live in a cold climate in Canada and we bought our 1974 house last year and it has a double detached garage. The garage is uninsulated, not heated, exposed OSB and this winter/spring we noticed significant frost and subsequently water once it got warmer on all of the OSB walls and roof. Everything was just soaking wet. I've attached photos. You can see the exposed siding/roofing nails had a thick buildup of frost on them. The garage is uninsulated which is fine, we know others with uninsulated garages here just like ours and they do not experience this issue. I know parking the car with snow on it and snow melting in the garage can cause this, but we tried parking in the driveway for a while and the issue still occured.

The garage has no soffits / vents, but has no enclosed roof. Would adding some venting/ perforated soffit help with this? Once we noticed the issue we started leaving the man door open 24/7, which seemed to resolve the issue, but is not a permanent solution for obvious reasons.

We are desperate for some answers here before next winter, if anyone knows why this might be happening or can offer some advice/potential solutions it would be greatly appreciated.

Thank you

I'm guessing you have an open shell of a garage where you can look above you and see the underside if the roof decking that supports black asphalt shingles. And as your eyes move down from the roof, you see nothing but OSB until you get the the walls where you are looking at open stud bays with exterior OSB.

Assuming this is the case, here's what's happening:

The roof is causing the entire garage to warm up when it's closed and the sun is shining. Warm air holds a lot more moisture than cold air. The rising temperature inside raises the dew point in the garage considerably. The warm moist air in the garage stays there overnight as the cold night air chills the structure of the garage. This condenses out the moisture from the trapped air overnight and is why you wake up to frost and/or soggy OSB in the morning.

This is why leaving the garage door open 24/7 seems to correct the problem-- the warm, moist air doesn't get trapped inside the garage and the are inside stays at equilibrium with the outside.

This is also the similar cycle of events that gives us morning dew and fog and even frost on the grass.


That means the solution has a couple aspects to it:
-- Insulation to slow the rate at which the garage temperature rises and falls. (foil faced iso or EPS board under the shingles, perhaps?
--Air sealing to keep the vapor drive from sucking in replacement air (and moisture)
-- Venting to allow interior air to equilibrate with outside air by exchange and convection instead of by condensation.

There's a reason that houses have housewrap and rigid foam and such. It's all part of managing the thermal and vapor drives as the sun heats (and darkness cools) the structure and the ambient air.