Best way to insulate basement slab
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I’m trying to decide how best to insulate a basement cement floor before finishing it. It’s a walkout basement, so there is a sliding door. The door has about 1.9 inches of clearance (see photo). For reference, I am in climate zone 5A.
The slab is uninsulated. It was poured as 4″ conc. floor on 6 mil visqueen over 4″ min. comp. gravel base.
Would DRIcore Insul-Armor be my best option?
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i'm not an energy expert so I won't comment on this eps board or any other one.
However, the addition of 1" of insulation plus whatever floor covering will raise your floor -- at the slider, this is good. At the stairs, it creates a trip hazard. Your steps will all have a nominal 7.5" rise until you get to the bottom and have a short riser. This condition is dangerous, nonconforming to model building codes and can lead to falls.
You will need to incrementally raise each step to make up this distance, reset your stringers out of level [not recommended] or make a new set of stairs. it's another wrinkle in your project planning.
I haven't used the Insul-Armor personally but it looks like a decent product for the application. Using EPS foam, it's slightly "greener" than XPS, and I wouldn't recommend polyiso insulation for a basement slab. With 1" thickness, you can still use a floating floor system above it, even one that's 3/4" thick. Or even a 5/8" T&G subfloor, (something like Advantech)with glued seams, then a high-pressure laminate floor on it. That might be a bit more durable.
The concerns listed by Stamant1 above are legit. You will need to rebuild the stairs. If they're typical builder quality construction stairs, that's not such a big deal. If they're nice finished stairs, it's a bit more of a bummer. Either way, the new stairs probably cost the same.
Would using something like DMX 1step help with floor temperature? https://dmx1step.com/
The concrete was poured on 6 mil visqueen, so I'm not sure if using a product like DMX 1 step would create a moisture sandwich.