# Frost Build Up On Interior Garage Wall



## richw (Jan 4, 2008)

Hi Guys,

I've got a problem which I've been trying to figure out for some time. On one wall of my garage I have frost/ice build up occurring in the winter. The other wall is free of any ice or frost. I have an insulated garage door, and the house is a cab-over design so there is a heated space right above the garage (and thus insulated garage ceiling), however the two side walls are not insulated.

My going theory right now is that snow is melting off the cars and evaporating then freezing on the cold wall. However, why the one wall is just beyond me.

I have thought about insulating the walls and putting vapor barrier up to try to stop this from occurring, however I'd like to figure out why just the one wall suffers from this problem before I do as I don't want mold build up inside the wall (which I won't be able to see if I cover it up).

Any help or ideas would be appreciated!

Regards,
Richard....


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## Bondo (Dec 8, 2007)

> However, why the one wall is just beyond me.


Is it the North wall by chance,..??


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## richw (Jan 4, 2008)

Bondo said:


> Is it the North wall by chance,..??


Yes I believe so. But at -20C I wouldn't have thought that would make much of a difference.

Rich...


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## concretemasonry (Oct 10, 2006)

Just a bit of a guess based on living in a cold climate -

Most of the time the winter prevailing winds are from the north or possibly northwest. These walls would be the coldest and the first to condense or frost up before the others.

If you insulate these walls,the other walls will be colder and possibly frost up depending on the temperature and humidity.

You really have an uninsulated garage with no heat loss up or into the interior walls. Since you have no heat source (outside of the loss from the heated space through the upper and interior walls), it will eventually get cold. Your only possible heat source is the car that melts the ice and droppings. Insulation does not make a space warmer - it only makes it cool off slower.

An insulated door does little in an uninsulated garage except it usually fits better and has less gaps.


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## richw (Jan 4, 2008)

concretemasonry said:


> Just a bit of a guess based on living in a cold climate -
> 
> Most of the time the winter prevailing winds are from the north or possibly northwest. These walls would be the coldest and the first to condense or frost up before the others.
> 
> ...


Would it be worth while to insulate the remaining walls (to try to keep it above 0 in the garage except on really cold patches)? Or would an exhaust/venting system to vent the moisture be a better project?

Rich...


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## pavola (Nov 13, 2007)

Is is the entire wall, up near the warmer ceiling, or at the bottom? Snow banks against the wall outside?


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## richw (Jan 4, 2008)

Definately more ice near the top. No snow banks against wall outside.

Rich...


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## pavola (Nov 13, 2007)

As mentioned before, northern exposure has these issues. It is the coldest wall, so frost will show up there first. But heat loss from the ceiling is most likely causing this. Could be ductwork in certain joist bays (can you check this?) that are poorly insulated, and there will always be some loss through the floor and the connecting interior wall that collects at the ceiling. If you have vinyl siding its easy to check if the bond is insulated properly - the color will be slightly distorted in cold weather if there's heat loss present due to frost on the back side it. Wood and other siding products can show some signs too, just not as well. Make sure to check this bond area and fix, if needed, before insulating that wall. Insulating will help eliminate the frost on the garage wall by preventing the warmer air from coming in contact with the cold plywood. But, if the bond area is still frosting, then you'll be trapping some moisture there by insulating the garage wall. If this is an issue, and it's to difficult to fix now, don't insulate yet. Put a fan going to just circulate the air and this may be enough to do the trick for now. IMO, insulated but unheated garages should have something to create air circulation to help prevent these issues.


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## Ron6519 (Mar 28, 2007)

Open the wall. It sounds like you have an open area leaking warm moist air from the upstairs into the wall area. You need to seal the area. You might need to insulate, vapor barrier and tuck tape the area to keep the two areas isolated.
Ron


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