Foam Insulation Methods For 100 Year Old Brick Home
Last Post 05 Apr 2015 03:55 AM by Bill in Cambridge. 6 Replies.
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jayreUser is Offline
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25 Oct 2014 03:21 PM
I am currently working on a house that was bricked up in the early 1900s; the house is in Zone 5A. So far, all the plaster and wood lathe has been removed from the interior. The house has balloon framing I am in the process of reinforcing the studs. My current condition is an exterior layer of brick, 3/4” spacing between the exterior sheeting and the brick, and open studs. I am trying to go about this construction in the greenest and most effective way possible.

I have complete access to the walls from the inside. I was thinking about these two options for insulation:

I can drill holes into the exterior wood siding (from before the house was bricked up) and spray foam between the brick and the siding… but I am worried that closed cell foam might push out the exterior brick when it expands. Do you have any advice for what type of foam should I go about using for this?
or
I could put a thin layer of foam from the inside against the sheeting and studs and then insulate with regular insulation followed by drywall with no vapor barrier on the inside.

What do you guys think? I have attached two pictures (one of a wall I still have to reinforce and another wall I just finished reinforcing). Is there another foam insulation option or a more advanced method that I should consider? I would really appreciate any ideas, thanks!

Attachment: IMG_3449.JPG
Attachment: IMG_3451.JPG

jayreUser is Offline
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30 Oct 2014 05:02 PM
I just wanted to write a follow up to clarify. The attached illustration depicts the current condition of my wall. The plaster and the lathe is currently removed from the wall.

What I'm thinking of doing is spraying 1/2 to 1 inch of closed-cell foam along the inside of the stud and on top of the sheathing, which will serve as a vapor barrier. The remaining space will be filled with fiberglass insulation, and topped by 5/8-inch of drywall and latex paint.

Another option would be to spray low-density insulation between the brick and wood sheathing by drilling holes in the sheathing.

I'm currently looking for the best way to handle insulating my wall in its current condition, and would appreciate any suggestions you may have.

Thanks


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SurfsupUser is Offline
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31 Oct 2014 11:59 AM
I don't think you should drill holes in the sheathing and fill the air space between brick and sheathing. That air space is there for a reason (moisture control). The stackup you have seems to be similar/same to just about any recently built home with brick veneer. Brick, air gap, sheathing, studs...so there's nothing special about it. Or maybe I'm missing something here.


vettabuildingUser is Offline
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21 Mar 2015 09:48 AM
Hello Jayre,
As above, the airspace between the exterior sheeting and brick is to ensure good air movement, so not a good idea to close that area.
I am starting a similar project, and was wondering how or what you ended up doing.
I am leaning to foaming 2" of closed cell on the inside of the sheeting, and then fiberglass batt the remainder, with no vapor barrier.

Cheers


jonrUser is Offline
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22 Mar 2015 09:22 AM
Wet spray cellulose into the wood bays and then put taped rigid foam on the interior. Then drywall.


BadgerBoilerMNUser is Offline
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22 Mar 2015 09:58 PM
vetta's idea worked for me, 7 years and running.


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Bill in CambridgeUser is Offline
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05 Apr 2015 03:55 AM
What you are doing is very tricky. Any time you insulate inside a wall, the problem is the vapor condensation. As you cool the wall, the temperature inside and near the wall can drop to below the condensation temperature. And if you block it from going out in the winter, then you get screwed in the summer when it wants to come the other way. I suggest you download the wall gradient calculator by J. Mitchell (just google it) and look closely at the vapor performance using the appropriate numbers for what you propose. I did, and pretty much concluded that the only thing that worked for me in both summer and winter was to use Roxul (mineral wool batts) together with Intelloplus membrane on the inside. Intelloplus blocks vapor going out in the winter, but let's it through in the summer. A

I had walls exactly like yours in Maryland, and had to reduce the insulation to R-15 to avoid condensation in the summer. Compared the R-2 of the wall before, this was a big improvement, but less than I would have liked. I also was trying to save classic window frames so in some areas I went with 1 inch Roxul and 1 inch of aerogel. Not cheap, but no alternative. I know the foam guys love to sell stuff and promise perfect sealing -- and maybe they are right. But run the program yourself and see how it works out. What you want to look for is when the saturation pressure curve crosses the vapor pressure curve. If that is happening you will get water behind your walls -- which can come out as liquid, or just cause mold. And it can make the house feel damp and humid. So you need to design a wall that doesn't condense over the temperature range for your area.


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