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indiana_23

Do walls of slab-on-grade foundation need to be dampproofed?

J Indiana
last year

Hi all. Homeowner here trying to understand part of the IRC.


I have a slab on grade foundation and the stem walls were created with insulated concrete forms (ICF).


The part of the code I'm looking at (R406.1 Concrete and masonry foundation dampproofing) says:

Except where required by Section R406.2 to be waterproofed, foundation walls that retain earth and enclose interior spaces and floors below grade shall be dampproofed from the top of the footing to the finished grade.


Does this apply to slab on grade or not? I, a layperson, would assume not. Technically, the floor/slab of our house is above grade. I can't find anything in the code that addresses slab-on-grade specifically.


However, the customer service person at the manufacturer of our ICF says that any wall below grade requires waterproofing.


I can't find anything in the code that makes an exception for ICF. Can someone please tell me if I'm reading the code wrong? Or if there is another section that deals with either slab on grade or ICF and damp/waterproofing specifically? Or perhaps there is an industry standard that is accepted but not necessarily outlined in code?


Additionally, I found this ORNL guidebook diagram that does not indicate damp/waterproofing in the detail (though it does indicate the protective layer that is required by code for the exposed insulation above grade). The documentation says waterproofing "is often not required," but that doesn't mean "never required."


Most of the stuff I've found specifically deals with crawlspaces and basements, not slab on grade. Hence why I turned to this forum. Thanks in advance!

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