Brick Veneer and Mineral Wool
Hi
We are getting ready to do a new house build and are having trouble coming up with a solution of how to attach brick cladding to the house shell with 3 1/2″ of external (Comfortboard 80) insulation on OSB aboveground and EPS below grade. Transitioning is proving troublesome. Any suggestions?
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Replies
User 7018119,
First of all, can you tell us your name? (I'm Martin.)
Concerning brick ties: Several manufacturers make brick ties for use with wall assemblies that include thick exterior insulation (continuous insulation like rigid foam or mineral wool). Here is a link to a Google results page with photos of many products:
Google results
More important, though, is a basic problem: Brick veneer is incompatible with exterior foundation illustration, because of the thermal bridging problem illustrated in the image shown below. If you want brick veneer, you have to insulate your foundation on the interior.
Is there anything we can do in this situation to fix the heat loss problem? Or, if you want Brick veneer you can wave goodbye to the idea of exterior insulation for the foundation.
Thanks
Jay,
Yes. In your situation using a slab on grade, you can minimize the thermal bridging by isolating your slab from the foundation wall. So your exterior insulation would stop at the sill plate of the framed walls, and below that the rigid insulation would run down the inside of the foundation wall and under the slab.
See the section labelled Bevel the Foam in this link. Your brick and ledge don't change much: https://www.finehomebuilding.com/2014/07/09/insulating-a-slab-on-grade
Hi Malcom, I apologize for the confusion beforehand. My example image doesn't explain my situation, I don't have a slab on grade foundation, I have a full basement. In fact, what Martin has illustrated is exactly what I was planning for. Is there anything I can do to remediate thermal bridging in this scenario? (I already installed the exterior insulation up to the shelf - depending on your answer...that may have been a mistake)
Thanks Martin for your quick reply.
My name is Gay.
And that is indeed the problem we are trying to overcome!
Some people have used aerated autoclaved concrete (AAC) block on the exterior, below the brick veneer up to the foundation sill level to provide the thermal break, but it's hard to find sources in the US. With a 3.5" brick + 1" air gap + 3.5" you have 8" between the foundation and brick face, which is a standard AAC width. (see: http://www.aerconaac.com/product-sizes.html )
A lower density 8" AAC runs about R10 , which isn't terrible- it's at least in the same range as 3.5" Comfortboard. If it's a 2-story brick veneer it may need to use something denser than the lowest density to support the weight, but since it's only supporting the brick, not the house, it doesn't have to be a higher strength (usually lower-R) version. A mid-density AAC would run about R8-R9 @ 8", still not terrible compared to the R1-ish thermal bridge of poured concrete.
As long as the AAC goes just a bit below grade you can do the rest of the exterior foundation insulation with much cheaper EPS rather than AAC.
See:
https://www.greenbuildingadvisor.com/article/does-autoclaved-aerated-concrete-make-sense
https://www.finehomebuilding.com/2016/02/12/an-overlooked-building-material-finds-a-new-booster
https://www.buildinggreen.com/news-article/autoclaved-aerated-concrete-aac-will-us-ever-lighten
Gay,
The usual solution is to design your foundation to have interior rigid foam insulation, not exterior rigid foam insulation, if your preferred cladding is brick veneer.
If you have a slab-on-grade foundation, see this article: "Insulating a slab on grade."
If you have a basement foundation or a crawl space foundation, see this article: "How to Insulate a Basement Wall."
There are also EIFS treatments that look like brick veneer, with the individual brick units created using a stencil pattern. Either EPS or XPS can be used as substrates. Look for StoCreativ Brick, Dryvit CustomBrick and BASF Faux Brick
Some of the EIFS manufacturers are now also creating systems for installation of thin brick or stone veneers bonded directly to an EIFS substrate. Look at Sto Energy Guard and Parex Masonry Veneer Systems.
Finally, there are thin brick veneer systems that are installed with steel clip hangers. Brick-It and TABS-II both produce systems that are designed for use over exterior insulation and include water and air barrier layers within the systems.
All thin veneer systems require some additional though about detailing for good aesthetics, and "outie" windows are generally easier and better looking than "innie" windows, but these are all options for brick-look while keeping a continuous layers of exterior insulation.