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Insulating interior brick wall


Laoprn's Avatar
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06-12-11, 10:46 AM   #1  
Insulating interior brick wall

I'm rehabbing a house in Chicago with 3 layers of brick wall and am wondering if I need to use a vapor barrier on the interior wall ? Im using foam type insulation with metal studs over the brick for the interior wall. Also wondering if it would be worth sealing the brick ?

 
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06-12-11, 11:13 AM   #2  
Hi Laoprn and welcome to the forum,
Not a pro on bricks, but as I understand it, they need to be able to dry, inside and out. I'll attach a science article which discusses a variety of brick walls. With three layers I'm not sure where the drainage plane should be.

Is your foam rigid cut to fit or spray in type?

BSD-106: Understanding Vapor Barriers — Building Science Information

Bud

 
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06-12-11, 04:52 PM   #3  
Its rigid cut to fit. Also do you know if there is any benefit to sealing the brick before covering it with the insulation ? Im jsut wondering if painting it or using a sealer would be considered the vapor barrier.

 
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06-12-11, 05:44 PM   #4  
Opinions on vapor barriers are changing. In your case, the inside paint job is probably all you need. That's the pretty paint job in the house, not the bricks. Along with the need for drying, I would think a sealer would be going the wrong direction. Add in the rigid foam is a good vapor retarder anyway and I would skip any extra vb. Just leave a gap between the rigid foam and the brick as they show in that link.

Bud

 
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06-16-11, 01:34 PM   #5  
Thanks Bud,
My business partner is concerned about wind/cold here in Chicago, do you think the insulation, drywall, etc is enough ? There are varying layers of brick (4 in basement,3 on main and 2 upstairs)we are dealing with and can feel the wind coming through while its stripped bare to the bricks. Thanks

 
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06-16-11, 01:53 PM   #6  
We tend to think of walls as just one layer, yet their function is broken down into air barrier, moisture barrier, and thermal barrier, with other functions all mixed in. Some layers will perform more than one function, insulation and air barrier for well sealed rigid foam, insulation and vapor barrier for foil faced foam, and so on. Some perform differently depending upon where they are installed, like tyvek over sheathing will work as an air barrier and drainage plane. Yet tyvek without something rigid behind it would no longer be an air barrier. As you can see, there is often no simple answer.

In your case, recognizing I'm here and you are there, I would consider pink or blue rigid foam as they have some permeability, not much at your thickness, but some. Where as foil faced foam would have zero. Then seal it in place very well to block any extra air circulation. Even though the plaster on the inside is also an air barrier, it is best to be sure those Il winds aren't blowing through. I've visited the windy city.

I'll add another link on vapor diffusion retarders.

Energy Savers: Vapor Barriers or Vapor Diffusion Retarders

If you cut to fit rigid foam and then try to seal any gaps with can foam, you will find it hard to fill small cracks. For some of the work I have done I found it easier to leave 1/4" gap and then fill with the foam. You will use a lot of foam, but the cutting and fitting will be a lot easier.

Good luck
Bud

 
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