Slab Vapor Retarder and Insulation With Radiant Floor Heating
Hi GBA Community,
I’m building a new home in Zone 5 and we’ll be pouring the basement slab very soon. I had a question about the general slab assembly since I’m installing radiant in the slab itself.
From what I understand you want the vapor barrier on the warmside of the slab above the rigid insulation.
Here was my plan
-4″ Concrete Slab
-10-mil vapor barrier
How does this change (if at all) if I’m installing radiant? Is it okay to puncture the vapor barrier with the foam PEX staples I plan on using to secure the PEX pipe to the EPS? Is 10 mil too thick? Will I have trouble puncturing it?
My other question is in regards to slab edge insulation. From a Penn State presentation it says that it is “one of the most abused details in construction” (https://www.phrc.psu.edu/assets/docs/Webinars/SlabInsulation.pdf) and that it should only be used where the slab is less than 12″ inches below grade. In my case I have a walkout basement on one side of my home for my garage and the other three sides are below grade (very similar to the diagram attached) Based on that diagram, I should only be insulating the slab edge on that side. Does the community agree with this? Does anyone have any suggestions on how to integrate the insulation with the slab where the garage opening is?
Thanks for your help.
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