# Superior Walls frost at corners when it's very cold



## Mbcflower (Sep 8, 2014)

*Corners of exposed basement walls frost when it gets cold*

We have Superior Walls in our walk out basement. The two corners that are exposed, will frost at the seams in the corners when temperatures get 30 degrees or below. It is only these two corners that frost. Wondering if closed cell spray foam is the answer to solving this issue? These corners do not show signs of moistness at any other time during the year. 

Please give any thoughts or advise!!!


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## Mbcflower (Sep 8, 2014)

We have Superior Walls in our walk out basement. We have issues with two of the exposed corners frosting when temperatures get really low. I was told this was most likely an air flow issue. That we need to insulate those seams to stop cold air and warm air condensing. I thought closed cell spray foam would help. Just wondering if I'm on the right track??? These two corners show no signs of moisture during any other time of year. There is also NO condensation on the door or windows in the basement.

Any advise is welcome!!
Thanks!


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## SeniorSitizen (Sep 10, 2012)

Mbcflower said:


> We have Superior Walls in our walk out basement. We have issues with two of the exposed corners frosting when temperatures get really low. I was told this was most likely an air flow issue. That we need to insulate those seams to stop cold air and warm air condensing. I thought closed cell spray foam would help. Just wondering if I'm on the right track??? These two corners show no signs of moisture during any other time of year. There is also NO condensation on the door or windows in the basement.
> 
> Any advise is welcome!!
> Thanks!


The reason there isn't condensation on the door or windows, the room temperature is keeping those surfaces above dew point temperature. Insulated doors and dual pane windows are actually insulated on the exterior. That is, insulating the cold air from the interior surface where condensation would appear.

Insulation on the interior of the walls prevents the walls benefiting from room temperature and those wall sections above exterior back fill grade line are getting cold enough to condense moisture while the portion of the walls below grade are earth insulated from the exterior cold and remaining above DP temp. 

So in conclusion we can see the most sensible solution is to insulate the exterior and prevent the walls interior surface ever coming down in temperature to dew point or below.

What interior insulation would ever work to prevent condensation I do not know. But I do know the interior wall surface temperature must stay above dew point temp. and any interior insulation must prevent the air within the living space from reaching the interior wall surface if the dew point of that air is above wall surface temperature.

This handy calculator will give some indication of the numbers required.
In the example ( adjust if copy numbers don't transfer ) we can see that if the room air temperature is 70°F, and the relative humidity is 45 percent the wall surface temperature must stay above 47° to prevent condensation. Keep the calculator handy and run some numbers this winter when the weather is conducive to condensation problems.

http://dpcalc.org/


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## Mbcflower (Sep 8, 2014)

Our exterior basement walls have vinyl siding on them at this point. How would I insulate the exterior walls?


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## SeniorSitizen (Sep 10, 2012)

Mbcflower said:


> Our exterior basement walls have vinyl siding on them at this point. How would I insulate the exterior walls?


We both realize exterior insulation would have been much simpler during the planning and construction stage but you might consider contacting superior and see what they say.


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## Windows on Wash (Aug 30, 2011)

Corners are usually big thermal bridges and that is what it appears like here.


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## Mbcflower (Sep 8, 2014)

I think you're right. This has been the common consensus when I've had people out to look at the area. Superior Wall corners have a bead of caulk that runs in the corner seams. At these two seams is wear frost has appeared. The rigid board runs along side it. I'm having closed cell foam sprayed in these corners as well as the rim joints in hopes to seal up any air penetration.


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## mikegp (Jul 17, 2011)

Has the sealant they used failed? I've read many stories that their walls have issues at the seams after a certain amount of time. I've even heard that right around the time the warranty ends that you sometimes need to re-caulk every seam. Sounds like a huge undertaking if true.


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## SeniorSitizen (Sep 10, 2012)

Mbcflower;1400322I'm having closed cell foam sprayed in these corners as well as the rim joints in hopes to seal up any air penetration.[/QUOTE said:


> What is the dew point temperature of the air you you will be sealing in with the closed cell foam ? If it is above the ( I don't know what the coldest the wall surface will ever be ) all you've done is hide the problem.


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## Mbcflower (Sep 8, 2014)

I'm not sure about that. I will say I put a dehumidifier in the basement and it has solved the issue of the corners sweating when the temperatures gets colder. Thankfully, they have been dry as a bone. I've not had them insulated yet. I first wanted to make sure the dampness would go away with removing the humid air before insulating. Now that I know it will, I can insulate.


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## Mbcflower (Sep 8, 2014)

We will most likely always have to use a dehumidifier. Before the insulation is installed, the dehumidifier will run to keep the humid air under control as not seal in moist air.


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## SeniorSitizen (Sep 10, 2012)

We can see by the link calculation if the room temperature is 65F with a relative humidity of 44 percent the wall surface will condense at 42°F.

Here's hoping it works for you.


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