Airsealing New Recessed Lights
Just had our 1960s home fully rewired. I did a lot of air sealing which is still in process but so far I’ve lowered our blower door result from 7.0ACH down to 1.8ACH.
We had halo recessed lighting added to our living room (the energy losses…gasp!) but I made sure they were ICAT rated at least. To my disgruntled surprise, these cans have tons of holes in them, which I’ve read is not unusual. I’m not sure how they are considered air-tight but ok.
Can I simply tape these holes shut? (Red circles in the picture) They are on the exterior of the recess can. I see no reason why not as they are rated to be air-tight but also questioning why they are there in the first place. The bulbs are LED.
I’ve seen the retrofit domes that fit over old recessed lights, however, taping seems way simpler plus I can keep the insulation right next to the can in the attic.
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This article is a bit old, but it might be helpful: https://www.greenbuildingadvisor.com/question/recessed-can-lighting-airtight-housings-airtight-baffle-trim-or-air-seal-from-attic-with-boxes
Note that the "airtight" part of the assembly is the trim piece.
Ah good info. So perhaps the actual can won't matter much. Once we get painted and have the final bulb and trim in place, I'll do another blower door test and see how much they actually leak. Maybe with the trim in place, it won't actually be too bad.
That's not entirely correct. "Air tight" recessed lights aren't really "air tight", they are just less leaky. I usually tape over holes and seams with foil tape myself, but the gasket where the housing is supposed to seal to the drywall is a bit of wishful thinking -- it's not very good gasket, the material isn't usually applied very well to the can, and it's probably not going to seal too well to what is likely a pretty rough drywall edge around the hole.
The air tight trim is only part of the assembly in some cases, not all. I have found the commercial Halo cans, which are only available from electrical supply houses and not the box stores, are FAR FAR FAR better quality than the stuff the box stores have. I'm not going to say they're great in regards to air tightness, but they are more solidly built, have better screw-driven mounts (in the case of remodel style cans) instead of spring clips, and seem to be made using heavier materials and more attention to detail in general.
If you use a relatively air tight LED trim in the can, you're going to be about as good as a can can get in terms of air tightness. This is what I've done in my own home, since the can offers a sort of standard "enclosure" that will allow for easy replacement of the LEDs in the future, if needed. That's the one concern I have with the flush-mount LED lights -- if they fail, replacement can be tricky, and who knows what you might be able to get years in the future. Cans solve that particular issue. I do try to avoid using cans in ceilings that are under attics though, where the air leakiness matters the most.
You should not tape those hole since they may be there to allow the heat to escape (applicable with halogen bulb). You should try and install a vapour barrier boot such as the one below sold at Home Depot.
The alternative it to purchase the newer slim LED which are about 0.5 inches thick.