I haven't had to airseal any can lights in several years. I have a client who has many can lights throughout his house and wants to have them airsealed and then insulated over. Several years ago I would have just slapped some light covers over them and foamed them in place to airseal. While I'm looking at purchasing light covers such as the Insul-Lite - 10" x 10" x 12" they aren't too far apart in price from the can light LED retrofit units. My thought is it still considered best practice to leave existing can light alone and still airseal with the light cover from the attic side OR is it better these days to install the can light LED retrofit with some weatherstripping on the underside of the can? If the can light isn't IC rated would installing a weatherstripped LED and then insulating over it be a cleaner looking, better end product for the customer? It would seem that this would be a feasible option, especially with a house with a low pitch roof where you are struggling away in a low attic with little room to move around. The new LED would be significantly cooler than an old incandescent or halogen bulb and thus shouldn't have any risk of overheating. Does anybody have any experience airsealing can lights with both of these approaches and also might have blower door numbers and thermal images to back up their experiences? Any and all thoughts and input is appreciated.

Thanks and have a good weekend!


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  • Non-IC rated can lights should never be air sealed or insulated over, even with a protective box or cover to keep the insulation away.  Non-IC units are designed to ventilate and have no high-temperature-sensor cut-out switch as do IC-rated units.  IC units can be sealed and insulated over, but the occupant may experience unexpected cut outs due to overheating, but at least the house doesn't burn down. 

    Given we now have the option of the flush-mount LED units that can mount directly into the junction box, this would be my first choice. Next best would be an LED can retrofit kit but you would still want to air seal the can.  Although probably not approved by code, I'd probably feel fairly safe with replacing existing incandescent bulbs with LEDs and then boxing and air sealing the can...but as I said, it's probably not code approved.

    • Homeowner has already installed LEDs on vast majority of lighting in house and definitely all the can lights. I would only be installing the retrofits with the stipulation that incandescent never be put in the cans.

      I was emailing with somebody from Total Lighting Supply/Total Recessed Lighting Supply and they seemed to think that the LED module retrofit coupled with an air sealing gasket would be a good option but they were careful to avoid going into detail about heat/fire issues or making any air sealing claims.

      • I should have been clearer.  Although " I'd probably feel fairly safe with replacing existing incandescent bulbs with LEDs and then boxing and air sealing the can." I am not recommending this as a professional measure.  I am retired now and no longer need the C.M.A. but from a strictly technical standpoint, I don't think LEDs give off sufficient heat to be a problem.  Should there be a fire...no matter what the source...I would not want my name to be on a recommendation to air seal and insulate.

        My main concern is I have seen far to  many recommendations that distill down too..."as long as the insulation is 3" away from the can, you have no problem. " This is definitely NOT the case.  Fortunately we do have options now and I would always strongly recommend replacing any non IC fixtures with LED options irrespective of the location or lamping.

  • With the new LED flush mount can light on a normal electrical rough in box we just caulk the rough in box to the drywall and caulk the wire penetrating into the box and any knockouts closed. Or foam them in. Havent had any issues with heat. 

    They do sell sealed gasketed rough in electrical boxes for lights and boxes. Just make sure the drywaller doesn't zip off the gasket when they use a rotozip. 

    The IC rated can lights still have some leakage and you can see this from the attic looking into the house on a sunny day. I foam them in where I see light. But, the old school method of creating a small plywood box and sealing it over the can light in the attic still works 2!

    • Just to verify, I'll be retrofitting existing can lights in an older home. I don't know how old the can lights are and there are likely 3 different generations of them. The safe assumption would be that most of them aren't IC rated. It sounds like you are dealing mostly with new construction? I wish I wasn't dealing with such a low pitch roof but that's what I have to work with. Biggest concern here is how effectively I can airseal these (probably non IC) cans with LED retrofits and not having any heat issues after I bury them with insulation. Sorry if we were already on the same page prior and thank you for your reply.

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