Question of the Day - #102 Basement wall insulation

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Question of the Day - #102 Basement wall insulation

Postby RDavidson » Fri Dec 12, 2014 10:18 am

Proposed MN Energy Code section 1322.0402, subpart 1, contains a table that specifies that basement walls have an R-value of 15. Footnote C, attached to this requirement says “see section R402.2.8.

R402.2.8 reads as follows:

R402.2.8 Basement walls. Walls associated with conditioned basements shall be insulated from the top of the basement wall down to 10 feet below grade or to the top of the footing, whichever is less. Foundation insulation shall be installed in accordance to the manufacturer’s installation instructions. Walls associated with unconditioned basements shall meet the requirements of this section unless the floor overhead is insulated in accordance with sections R402.1.1 and R402.2.7 and the following requirements:
a. R-15 insulation for concrete and masonry foundations shall be installed according to R402.2.2.2 to R402.1.1.8 and a minimum of a R-10 shall be installed on the exterior wall. Interior insulation, other than closed cell spray foam, shall not exceed R-11. Foundations shall be waterproofed in accordance with the applicable provisions of the International Residential Code (IRC).
Exception: R-10 continuous insulation on the exterior of each foundation wall shall be permitted to comply with this code if the tested air leakage rate required in section R402.4.1.2 does not exceed 2.6 air changes per hour and the total square feet between the finished grade and the top of each foundation wall does not exceed 1.5 multiplied by the total lineal feet of each foundation wall that encloses conditioned space. Interior insulation, other than closed cell spray foam, shall not exceed R-11. See footnote c to Table R402.2.1.
b. Minimum R-19 cavity insulation is required in wood foundation walls. See footnote 1 to Table R402.2.1.

Does part a and b apply only to basement walls “associated with unconditioned basements”? Or, do they apply to conditioned basements as well? There is only one charging paragraph.

In part a, why is the waterproofing requirement different here than it is in R402.1.1?

There is a radon presentation on the DLI website at http://www.dli.mn.gov/CCLD/PDF/edu_radon.pdf. Slide 100 in this presentation shows all of the details for a basement wall including drain tile, waterproofing, etc, and a conditioned basement. It shows R-10 insulation on the exterior. If part a and b do not apply to conditioned basements, why does this teaching aid show the wrong R-value for the basement wall? Was this an error? What R-value is required for basement walls with conditioned space?

Does part a and b apply to all basement walls?
RDavidson
 
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