Insulation, Radiant and Vapor Barriers - Recessed Lighting

How do you keep warm air from infiltrating the attic from recessed light fixtures? The ones we bought are not "air tight", but IC. (Insulation Contact).

I had to cut open the second floor ceiling, and unfortunately, cut a hole in the floor of the unused attic, since the cans extend only an inch or so above the floor of the attic.

Should I jamb some polystyrene in the joist area, and build a box of polystyrene or sheetrock above the attic floor?

The "air tight" cans are pretty spendy...:eek:

Go into the attic and put cut pieces of foamboard in the bigger holes around the can if necessary and the use a can of sprayfoam to seal it all airtight. The sprayfoaming part is key.

I just bought airtight cans at home depot for $6 each, not so bad. note that they're not air tight if you don't use air tight trim kits.

I have used cut pieces of foam board to do this on my own home. Build a box around can and use the 'foam in a can' stuff to seal around it. Just make sure you provide the recessed light can with some room to dissipate heat, even though it's IC rated...say 2-3 inches around it. Then if you can, insulate on top of it with blown-in cellulose or something else. Ideally you want more than that R-5 foam board around that space where the light is. good luck, i wish i didn't have recessed lights, pain in the butt.

Yup...I'm finding that out. But, they look nice when you're done...:rolleyes: