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Community and Q&A

Can light insulation

skeutzer | Posted in Energy Efficiency and Durability on

This topic has been talked about a lot, but I notice a lot of the info dates back before LED’s became readily available/affordable.

I have about 30 can lights scattered through my house, and I want the best method of sealing them better. They are IC rated but not air-tight. They are mostly covered with blown-in insulation in the attic. Most of the fixtures are accessible from the attic, but some are are located very close to the outside perimeter, so they would be very difficult to get to from the attic (low clearance).

My main concerns are probably more for comfort, but any energy savings would obviously be a plus. My house is about 50 years old, and is drafty/uneven in the winter. In addition, I get a strong “attic smell” in the summer when it gets hot and the AC is running. So I have reason to believe these things are leaking considerably. I live in St. Louis, MO where the weather swings from 0F (or below) in the winter to 100F (or higher) in the summer.

My options are:

1. Keep using existing fixtures, cover with more insulation. Maybe caulk/seal around edges?

2. Replace with air-tight fixtures ($10 per can).

3. Add retrofit kits that fit into existing cans ($10-$15 per can). Do these offer adequate air sealing? I’ve already replaced my bulbs with LED so this seems a little wasteful.

4. Add covers over can lights in the attic (purchased at $15 per can)

5. Make my own covers using drywall boxes ($2-$3 per box. Cheaper but more work)

6. Some combination of above?

Where will I get my best bang for the buck? What is the best way to seal around the perimeter of the cans? Is there something like a foam gasket available and do they work well?

Thanks in advance for any help!

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  1. GBA Editor
    Martin Holladay | | #1

    The quality of your results will depend more on how conscientious you are with your air sealing work than on which approach you take.

    You forgot to mention one option (perhaps my favorite option): Remove the existing can light, and replace it with a shallow electrical box (ideally, an airtight box, but in any case a box that is easy to air seal). Choose a shallow box that can accommodate one of the new "pancake" LED fixtures that look a little like a recessed can light. Of course, you need to make sure that you caulk the crack between the ceiling drywall and the electrical box, and that you caulk the hole where the electrical cable enters the box.

    Here are links to two relevant articles:

    Rethinking Recessed Lighting

    Canned Lighting Conundrum

  2. dinnerbellmel | | #2

    Question: can you get some LED retrofit kits like the ones sold at Lowe's and use some rope caulk like below to use between the LED fixture and drywall? I would imagine that would be fairly air-tight at that point. You could also caulk the LED fixture to the drywall but that seems to be a much more permanent solution to using rope caulk.

  3. skeutzer | | #3

    Thank you, Martin and Mel, for your feedback. I did purchase a couple of the retrofit kits, and I'm pretty impressed with how easy they are to install, and they put out some really nice light - probably nicer than the standard LED floods that I have been using (they were a little higher powered so that might have something to do with it). I like the rope caulk idea, I was trying to think of a good trick to seal the trim to the ceiling.

    I also notice they are selling housings that only work with special LED bulbs (as opposed to standard bulbs). Does anyone have experience with those? How expensive are the bulbs that go in those?

    As far as replacing the fixtures completely, that is probably more work (and money) than I am willing to do at this time. It could work for some of the rooms, but not all. I won't rule it out completely, at least for one or two rooms.

    My solution is likely to be a mixture of the above methods, and will likely span over the next few months as I try different things. I do have a couple of cans that are really loose to the drywall, and the clips do not work well, so I will likely be replacing the bad ones with IC/AT fixtures. I might have to patch a little bit around the perimeter on some of them too. Most of the cans still appear to be attached pretty tight to the drywall (with a layer or two of paint holding it more).

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