# Basement in Winnipeg



## owch15 (Aug 21, 2016)

New to the Forum and looking for some help. I live in Winnipeg, MB and I am insulating my basement. I am using Roxul comfortboard. Do I apply it directly to the concrete wall or should I use an air/moisture barrier next to the concrete. Summer is average 30° with higher humidity and winters are cold ave -20°C. Mainly clay soil. Thanks for any advice.


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## lenaitch (Feb 10, 2014)

I am not familiar with that particular product (Roxul batts only) and took a quick look at the Roxul website. It looks like 'comfortboard' is intended for exterior use. Best to check whatever instructions that came with the product or contact the manufacturer.


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## owch15 (Aug 21, 2016)

Thanks, I did check on the comfortboard IS and they do recommend its use interior but I'm just not sure if it needs a air/moisture barrier between it and the concrete wall.


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## Bud9051 (Nov 11, 2015)

There are three objectives.
1. To meet your code insulation requirements.
2. To keep warm humid summer air away from the first surface below the dew point.
3. Same as #2 but also allowing moisture vapor to dry to the inside.

#3 is difficult to explain because most people like to think of their basement as being dry, few are. Im most cases, besides actual water problems, the moisture in the soil outside is constantly passing right through the foundation walls and evaporating to the inside before it accumulates where you might see it. Add a vapor barrier anywhere in the assembly and the exterior side of that VB will be come just as moist as the soil outside. If your safe and sound insulation is between the Vb and the foundation it may get wet.

As for using the safe and sound, how thick will it need to be to meet your code requirements? I didn't find your exact location, but northern Minnesota requires R-15 for continuous insulation or a 2x6 wall with r-19 in the cavities. You will need to determine your location requirements.

But, r-15 continuous would be 3+ inches or safe and sound if memory serves me. Not sure if you were planning on that amount.

Bud


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## owch15 (Aug 21, 2016)

Thanks, Bud..Our minimum code in Winnipeg is R-20. The combo of the Roxul Comfortboard and the Safe and Sound will meet that. The Comfortboard is the same make up as the safe and sound just compact at 1.5". I have read in some forums that you can put the ComfortBoard right against the concrete to create the thermal break or you add an air barrier, I am assuming like Tyvex...I think. To let air movement without moisture and let the concrete breathe. I'm just not sure which way to go or what material would be sufficient as an air/moisture barrier.


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## Bud9051 (Nov 11, 2015)

I have not used the safe n sound or comfort board so no help in attaching it to the foundation. You can educate me on that point.

How will the wall be finished, any drywall or studs on the inside?

Just did a search and have not completely read this link but it sounds close to home and applies to the topic at hand. The moisture they are encountering is coming through the lower portions of the wall and being carried by air circulation up to the above grade foundation area where it accumulates as ice. The answer to this issue has been rigid insulation which does not allow air to flow through it. Have you ruled out rigid insulation?

http://homes.winnipegfreepress.com/.../Icy-basement-walls-common-in-new-homes/id-93

Bud


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## davidmr (Dec 18, 2015)

Have you bought the comfortboard? If not you would be far better to use 2" rigid foam.

Homedepot & rona both sell 2" Durafoam, its cheaper then comfortboard. The benefit is the rigid foam will stop air movement into the wall preventing condensation within the wall, 
Comfortboard doesn't do that, it will allow moist interior air to pass through, once that air reaches the cool concrete wall it could condense on the concrete which could lead to moisture/mold trouble. 

After the durafoam, You can still use the roxul batts between the studs to get you R20.

Another alternative is to frame the wall and have it all spray foamed.. Look into the costs, if its not much more it really is the best way.


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## stick\shift (Mar 23, 2015)

Why would you use Safe N' Sound in a basement? I would get the Comfort Batts to get maximal insulating capability.

I'm with David on looking into rigid foam instead of the Comfort Board as well.


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## Bud9051 (Nov 11, 2015)

I'm waiting to hear how the walls will be finished. If studs and drywall then the drywall can act as an air barrier and a thermal barrier if rigid foam is used. If the safe n sound is being used to avoid the need for a thermal barrier and is intended to be left exposed then there are air sealing concerns.

Need more info so I can stop guessing.

Bud


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## davidmr (Dec 18, 2015)

the comfortboard is a bad idea any way you look at it, regardless of how/where the air barrier/vapour barrier is placed.

If you use a vapour barrier on the inside, then during the summer moisture could come in from outside through the concrete and be trapped within the wall assembly...

If OP must use comfortboard, then look into certainteed's smart MemBrain on the top half of the wall.

But again, a product like durofoam would be cheaper and have better results.


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## Bud9051 (Nov 11, 2015)

I just went over to Roxul's web page to review what they are advertising and although the are showing the comfort board directly against the foundation followed by studs with batts in the cavity, I agree with you David, I would prefer a rigid foam.

Even if we accept their advertising, not every basement is the same and renovating an older basement can result in enough food for mold already being in place on those walls. Mold it just too big of an issue to take a chance.

If the op has other reasons we will have to wait to hear.

Bud


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## davidmr (Dec 18, 2015)

I think there system assumes a well water proofed foundation that wont allow any moisture to migrate from the exterior... Basically a new house with a dimple membrane.. It's to bad people with existing older houses get sucked into there advertising.


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## owch15 (Aug 21, 2016)

Thanks for the insight. Spray foam isn't any option cause members of the family highly sensitive to smell and the off gassing of the foam wasn't worth the risk. I had already purchased the Roxul Comfortboard IS. I applied it over Tyvex moisture barrier. The basement will be finished with Roxul comfort Batt under drywall.


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## davidmr (Dec 18, 2015)

Ok... I recommend you find certainteed's smart MemBrain and place that under the drywall. If you want to save money you can do just the top half with this and use regular poly on the bottom 4ft.. Tape the seams and seal as normal for poly.


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