Insulation on foundation – where to place it
srasic
| Posted in General Questions on
Hello,
Hoping to get some advice regarding the typical placement of Rockwool Comfortboard when covering the exterior of a foundation. Specifically, should it be positioned inside or outside the drainage mat?
I came across a detail from Rockwool that illustrates placing it inside the drainage mat. I’m assuming this would require either wrapping the mat over the Comfortboard meaning it wouldn’t extend up past grade. Or I guess you could run the terminate the drainage mat right on the Comfortboard and run it as high as you’d like?
I’ve also seen others place the Comfortboard on the outside of the drainage mat, resulting in a more traditional waterproofing where terminate the drainage mat on the foundation and you can extend the Comfortboard to your desired height. Just wondering if there are pros or cons to either approach and what the usual practice is among those with experience?
Thank you for your help!
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I work for ROCKWOOL insulation and can be reached at [email protected] also.
The detail you are showing is our best practice detail with the drainage board outside of the Comfortboard. That being said, you can also reverse that as it is below grade so air movement in the drainage mat isn't a big deal. Since Comfortboard is termite resistant, it doesn't need to be covered. We also have details without the drainage mat but if you live in an area with clay soil, it is better to increase the drainage potential with the mat.
danedelman1979,
Is there any danger that the rock-wool can become saturated with mud if it is left exposed outside the drainage matt?
There is no danger and will only go into the first 1/8" if anything. personally, I like to add sand into the soil that is getting backfilled around the foundation to increase drainage.
Thanks! Great to know.
Thanks Dan! I will send you an email. Appreciate it!