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Recessed can lighting — airtight housings, airtight baffle trim, or air seal from attic with boxes?

Chris Albrecht | Posted in Energy Efficiency and Durability on

How effective are airtight recessed can lights with regard to energy efficiency and indoor air quality? Would you say that they’re worth the added expense?

How much can be gained by retrofitting an existing standard (not air tight) recessed can with air tight baffle trim? Is air tight baffle trim worth purchasing and installing in existing standard cans?
Will installing an air tight baffle trim eliminate most of the air leakage from standard recessed can lighting?

Will retrofitting a recessed fixture with air tight baffle trim do nearly as much as installing an air tight drywall box over the can light from the attic? Skip the air tight baffle and build the box?

Any recommendations on quality brands of airtight recessed can lights?

Thanks!

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Chris,
    Q. "How effective are airtight recessed can lights with regard to energy efficiency and indoor air quality?"

    A. So-called "airtight" recessed can lights are not airtight, but they leak less air than recessed cans without weatherstripping at the trim. The best approach for an energy-efficient house is to have no recessed can lights in an insulated ceiling.

    The airtightness of your ceiling fixtures has no effect whatsoever on indoor air quality -- unless your method of improving indoor air quality involves the deliberate construction of a leaky house. This is not a recommended method.

    Q. "Would you say that they're worth the added expense?"

    A. The expense is trivial. If you have your heart set on recessed can lights in your insulated ceiling -- a mistake, in my opinion -- then of course you would choose to install so-called "airtight" versions. In fact, this is a code requirement. Choosing recessed can lights that aren't airtight is a code violation.

    Q. "How much can be gained by retrofitting an existing standard (not airtight) recessed can with air tight baffle trim?"

    A. If the brand of recessed can light that you have can accommodate trim with weatherstipping, it would probably be a good idea to install it. But that still doesn't address air leaks through the can itself, and through the electrical cable penetrations at the top of the unit.

    Q. "Will installing an airtight baffle trim eliminate most of the air leakage from standard recessed can lighting?"

    A. No.

    Q. "Will retrofitting a recessed fixture with air tight baffle trim do nearly as much as installing an airtight drywall box over the can light from the attic?"

    A. No. Installing a box from the attic side is the preferred solution. You can use drywall or rigid foam to make the box. Just be sure the box is big enough; be sure that the seams of the box are sealed; and be sure that the insulation piled on top of the box is deep.

    Q. "Any recommendations on quality brands of airtight recessed can lights?"

    A. I can't make any recommendations; perhaps some GBA readers will chime in on this point.

  2. Jesse Lizer | | #2

    The issue I have with a lot of fixtures that are surface mounted is they are typically not very attractive, especially if used in the kitchen. I tend to use cans in the kitchen, but that is about it. I figured for these 4-8 cans, we can either build the box or install an attic seal. What the insulators have been doing recently is shooting an attic seal. They either cover the light with a foam box or wrap it in batts, and then shoot about 2" of foam on the entire attic floor, over the fixtures, joists, etc. Cost-wise it does not add that much, and the drywallers do not need to mess with sealing around openings. I still gasket the top plates at exterior walls however.
    The pro to this is it gives you a nice tight seal around all fixtures, penetrations, etc. The con is now you have foam over everything, so re-wiring/fixing electrical can be a major pain. However really no different then shooting it in the walls. I realize spray foams are not always favored on this site, but I also believe when used spareingly, they can have a big impact with minimal added costs (such as attic seals and I also call for it in box sill areas).

  3. Chris Albrecht | | #3

    Sure...the best approach for an energy efficient home would be to have no recessed can lights. I'm inquiring from an existing home perspective where leaky can lights are currently in place and the homeowner is not willing to part with the fixtures. Just curious as to how much infiltration could be reduced by simply retrofitting the can with an air tight trim baffle. How effective are they?
    I have been building air tight boxes over recessed cans out of rigid foam board. I seal the seams with Tyvek tape, maintain 3" of clearance from the fixture, and switch the incandescents out with CFLs. The boxes get sealed down to the drywall ceiling with caulk, and wire penetrations are sealed with spray foam. Will probably continue to apply the tried-and-true method.
    Any GBA readers have any preferences on air tight recessed can manufacturers?

    Thanks.

  4. Aj Builder, Upstate NY Zone 6a | | #4

    Chris, the big box stores carry airtight items. You could seal up a can with silicone and firecaulk too. If the home burns down, please wait till I am dead to contact me. But the cans I get just have a seal on the bulb end and a seal to the drywall, quite simple. By far the best way to go is if the cans go into a fiberglass insulated attic space is to do what you do above already. And then heap up the cellulose over the glass along with maintaining your vent space along the perimeter.

    A ranch home with cans in every room, I would do the better work and I think much more to stop the airflow from cellar to attic.

    A home with one room and two to four cans, add gaskets. Can't really be worth doing more.

    I have used dozens of these with standard cfls.

    Home Depot
    Halo Air-Tite 6 in. Baffle Trim
    Model # 30WATH
    Internet # 100089636
    Store SKU # 677978

  5. David Meiland | | #5

    In an attic situation, you can get IC/AT cans almost air-tight with a little bit of work, but I think you need a blower door or other source of pressure differential to do it. Canned foam is the main thing I use, and part of it goes on with a very small nozzle adapter that gets the foam between the two layers of the metal can visible from below (at least on the Halo type I usually use). I put four of them in my kitchen and was able to get them so they wouldn't take any smoke from my smoke pen with the house pressurized.

  6. Chris Sherwood | | #6

    I'm building a new house and realized too late that I didn't ask for air tite recessed lights. And I have a lot of them (about 30). I spent the weekend sealing all other holes in the attic, but need to decide what to do with my Halo H7ICT cans. I think I will cover each with a foam box, either home made or purchased styrofoam boxes. I'm looking for sources. Any suggestions on the best way to make/purchase these boxes? Thanks

  7. GBA Editor
    Martin Holladay | | #7

    Chris,
    One brand of airtight covers for recessed cans is the Tenmat cover. Read about it here: New Green Building Products — September 2010.

  8. Chris Sherwood | | #8

    Martin,
    THanks for the quick reply. The price, and the fact that you can't use incandescent bulbs, probably means I'll look for something else. I've found styrofoam coolers for about $6 each, so may go that route.

  9. David Meiland | | #9

    The "IC" in H7ICT means "insulation contact", so you might go ahead and apply some canned foam judiciously to the housings from the attic side. The cans have a thermal shutoff in them to limit how hot they will get, and they'll likely never shut off under most circumstances. They will if they are over-lamped, and possibly if installed into a scorching-hot attic or cathedral ceiling.

  10. Bob Nickason | | #10

    You may purchase poly hats from any electrical wholesaler supplier which are made specifically for pot lights. They are marketed as vapour / air barrier poly boots for ceiling installations or areas which penetrate the vapour / air barrier.

  11. Dennis Heidner | | #11

    Two years ago we replaced the OLD fire hazzard recessed lights with newer IC rated recessed lights. If you do your research and carefully select brands, you will find recessed cans that are "more" air tight than others. The IC label has nothing to do with if they are air tight. An easy check is to see if the recessed can is approved for use within Washington State. If rated for "WA" that means the meet a minimal air tightness IF properly installed. THAT IS VERY IMPORTANT. Often air tight recessed cans require that you order ADDITIONAL GASKETS -- most big box stores don't carry the gaskets and they will not take the time to get them.

    As for the question -- do they work? We've been working on tighting our house and reducing its energy foot print. Last fall we finally had the blower test done on the house. Built in 1966 and about 3000 sqft. We tested at 2.8ACH 50. I stopped plugging air holes -- instead it was time to get an HRV. That 2.8ACH50 was made even though I knew about and could see about a dozen areas that were not sealled and would be significant leaks. Would this house ever make to .6ACH50 (PassivHaus) -- NO! -- not with recessed lights. But the house might make it down to 1.0ACH50.

    While testing with blower - we used a Fluke IR thermoimaging camera. That confirmed the cans WERE NOT the major source of the air leaks. The leaks were around plumbing holes that had not been sealed - some gaping holes.

    Sealing up a recessed can and trying to make them "more air tight" then they are rated for by the manufacturer will likely be a problem -- just waiting to happen. Yes, the newer cans have thermal breakers to help prevent over heating - but migh guess is they are also designed with the small air leakage in mind. Too tight and you may have flashing recessed lights in your house. There may be a balance. This is why you do the research and compare vendors ratings for air tight before buying.

    I would focus on very carefully reading the specs and installation instructions before you buy and install. If you can tolerate the leaks of the newer recessed gasketed cans - then use them if the lighting design makes sense.

    Don't try to make an air tight recessed can from a non-IC, or unrated "air tight" recessed can.

  12. James Morgan | | #12

    It never ceases to amaze the lengths folks will go to to compensate for the inadequacies of can lights when there is such a wealth of generally more efficient and attractive alternatives: pendants, ceiling fixtures, sconces, track lights, flex track, floor lamps, table lamps, uplighters, downlighters, cove lights......

  13. Michael Scott | | #13

    James, that's like saying you're constantly amazed by the fact that women like chocolate.
    It is what it is. Potlights are potlights and they've become ONE of the standards over the years for interior lighting......just like chocolate is a standard for candy.
    It may be dumb.......but, hey, so are black cars.

  14. redbera | | #14

    Looking for some advice on retrofitting leaky IC can lights:

    What about gluing/caulking baffled LED inserts (see pic) straight to the drywall ceiling? Seems like it would seal pretty good. The lights themselves have small seams that could perhaps be sealed with high temperature silicone caulk, though they are advertised as "air-tite"

    The LED insert come with gaskets to seal between baffle and drywall ceiling, but do basically nothing since it is hard to get them fitted tightly to the ceiling.

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