Basement – Can rigid foam board have an air space between it and the studs. Basement wall

basementinsulation

I finishing a part of my basement and I want to put rigid insulation>studs>batt insulation in stud bay>drywall.

I have a wall that has copper pipes, pvc pipes, and gas pipes flush to the concrete wall. There is also a main clean out on the floor that's about 2 inches away from the concrete wall.

I'm thinking about moving the pipes off the concrete and putting rigid insulation on the wall. Then frame my wall in front of the main clean out.

Is it okay to have an air gap of about 4in from the rigid insulation to the studs? Also is there a better way to insulate this wall because it requires moving a lot pipes. enter image description here

Best Answer

It's fine to have a gap between the rigid insulation and the energy wall IF you don't allow airflow to occur between the gap and your conditioned space. If there's free flow of air from on space to the other, the insulation in your energy wall effectively does nothing as you've now basically placed the insulation in the middle of the room.

This means relying on your drywall, plus something at the top of the gap, to completely block airflow. For that reason it may prove too complex.

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