What do I in my basement where new insulation meets old?

Steve J
Updated: Aug. 4, 2020

I’m insulating my basement with 2” of EPS against poured concrete foundation, then framing a 2x4 wall, then adding Rockwool. Unfortunately, due to some areas, like stairs and a laundry room which I’m not planning to demo, I’m unable to continuously insulate using EPS. Company’s directions are for product to be installed continuously against basement foundations.

Is this a cause for concern for moisture, air sealing, and different vapour methods and insulation types? (Old Poly vapour sheet and fibreglass insulation vs new Rockwool and EPS)

How do address the areas where the EPS is adjacent to the old insulation? 

If I demo the laundry room and continue with eps, how do I address insulation once I reach the stairs? The stairs are built two inches away from foundation wall. Not much room to work, or insulate, and I don’t really want to use closed cell spray foam, due to health concerns. Thank you.

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