# Help!! insulation inside a return air supply that uses the floor joist cavity as the



## just_a_guy (Oct 22, 2014)

I have a return air supply in my basement, and it uses the space/cavity between the floor joists as the supply/ duct. I believe this is often referred to as joist panning. I want to insulate inside this, what do I use? Or could I install metal sheeting 3 inches into the joist cavity instead of at the bottom? There would still be a 14inch x 5-6 inch cavity remaining. I want the insulation primarily to reduce noise coming through the ceiling. What about using 16" x 25' Roll Reflective Foil Double Bubble Foil Insulation"? thank you


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## Windows on Wash (Aug 30, 2011)

Why do you want to insulate it? Its inside the conditioned space isn't it? 

Panned ducts are crap at the end of the day when it comes leakage. 

If they are sweating, you just need to insulate the exterior.


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## just_a_guy (Oct 22, 2014)

A lot of noise comes though ceiling from this cavity


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## Windows on Wash (Aug 30, 2011)

Insulation will do little to impact that. 

Are you going to finish the basement? If so, that would be the time to address that.


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## beenthere (Oct 11, 2008)

Metal panning is very conductive to sound transfer. You could remove it, and use thermal pan. Its sort of a card board. Does transmit sound as much. But won't stop it all together either.

That a return, not a supply. Supply blows air toward a room, return draws air toward the air handler/furnace.


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