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Where does insulation fit in below grade waterproofing?

noaway | Posted in General Questions on


I am aiming to waterproof and insulate some below grade concrete footings I am trying to understand where to orient the dimple mat in relation to the insulation. Is this right or should the dimple mat be in between the concrete and the insulation? I am right on the edge of 6b and 7b.

I have also seen Type-II EPS recommended as below grade insulation. Are there any preferred products to fill this role? 

Many thanks!

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  1. Expert Member
  2. noaway | | #2

    Thank you @Michael!! I got an account to read your articles and I have a few followup questions if you don't mind. I reuploaded the image but I see now I should add a flashing at grade and not just at the top.

    As far as the flashings - do you have a strong feeling about what kind to use? Would something like this be sufficient if it covers both the dimple mat and the exterior insulation? ( Or would it be better to choose a system that has a purpose made trim for this purpose? The polywall system I was looking at doesn't seem to offer a top trim.

    Prior to your articles I was only aware of Polywall's system for this but I see now there are many systems on the market. Do you recommend any of these systems over the rest?

    What kind of insulation would you recommend for this purpose? I have seen that Roxul comfortboard has an approved product for below grade application and I like that for it's fire resistance but people on this forum seem to prefer Type-II EPS for it's compressive strength. I am having trouble finding Type-II EPS near me though but I might not be looking in the right places. Do you have any recommendations?

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