Remodeling… Wall detail and stone facade issue
I am in zone 5 (central Ohio). House is single story over basement on one side, two story over crawl in middle and garage on slab opposite side. Current wall is: sheetrock, poly sheeting, 2×4 w/ batt in cavity, T1-11. Front of house is the same but instead of T1-11 its 1/2″ fiber board with stone facade on the first floor. Roof is shallow pitch with 24″ eaves. The siding is in really bad shape and the poly is a typical 1960s application aka anything but air tight.
My original thought is to go with:
Roxul batt insulation in cavity
1/2″ OSB
DB+ or equivalent smart barrier
2″ Roxul 80 x2 layers
1×3 vertical furring strips
WRB
Royal DuraPlank (is this product still made?)
Establishing a continuous air barrier outboard of the studs is convenient being that I’m re-siding anyway. It also has the added benefits of:
-eliminating the need for detail sealing drywall penetrations
-eliminating need for poly installation during interior rennovations
-will not be compromised by any future interior rennovations
-easily extended to mudsill
However, the question becomes how do I approach the stone facade wall? The only way to add insulation would be inward, which is doable but it still leaves me with a broken air barrier and does not address the lack of vapor control.
Am I looking at tearing down the stone as well?
Thanks!
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Replies
Scott,
In the title of your post, you refer to brick veneer. Then in your first paragraph you refer to a "stone facade." Then, near the end of your post, you refer to a "brick facade." So what is it -- brick or stone? [Edit: Scott says he meant to write "stone." The original post has been corrected.]
I'm confused about the stackup you propose. It sounds like you plan to install a smart vapor retarder (DB+) on the exterior side of your OSB sheathing. But this product really belongs between the interior side of your studs and the drywall.
Concerning your brick veneer wall (or your stone veneer wall): The best approach is probably to install a layer of closed-cell spray foam on the interior side of your 1/2-inch fiberboard sheathing. If you end up following the flash-and-batt (or flash-and-fill) approach, you'll need at least 1 inch of closed-cell spray foam. For more information, see Flash-and-Batt Insulation.
Thanks for the quick reply.
Sorry, I noticed the flip/flop but did not see any options for editing the post. It is definitely at stone veneer.
While researching service cavities for the planned interior renovation, I came across this project and then read a few articles questioning ADA and then a few more about smart vapor barriers etc. It appears to me that establishing an continuous air barrier is more important then its exact location (ie one side of the stud or the other).
Regarding the flash and batt approach... Foam between studs may form an air barrier and increase R-value in the wall but it does nothing to prevent capillary wetting of the studs. Furthermore if I then add a vapor barrier on top of the studs wont I end up trapping moisture between it and the foam?
Scott,
I have edited your post by changing "brick" to "stone."
Scott,
Yes, you can certainly establish an air barrier on the exterior side of the OSB. The easiest way to do that is simply to tape the OSB seams with a high-quality tape like Zip System tape or Siga Wigluv.
If you want to use a European membrane as an air barrier on the exterior side of the OSB, you would choose an exterior membrane (basically, a water-resistive barrier or WRB) like Solitex Mento, not an interior membrane like DB+.
Scott,
Concerning the risks of moisture problems when trying to insulate the stud wall on the interior side of your stone veneer: You're right, there are risks. The best approach would certainly be to remove the stone veneer and put the materials in a dumpster. Then you can rebuild the wall properly, with new sheathing, adequate flashing, a high-quality WRB, a proper rainscreen gap, and new siding.
But that's expensive.
Deciding how risky the existing stone veneer is takes judgment. Is the wall protected by a roof overhang? When you open up the wall on the interior, are there signs of moisture damage?