Top hats for recessed LED lighting
We’re doing a top-to-bottom remodel on a 50-year old ranch home. We removed all of the attic insulation in this process and lighting will be installed before we re-insulate the attic. The lighting includes several recessed LED downlights. The fixtures are ICAT rated and include gaskets on the trim flanges that – in theory – seal the fixture to the drywall.
Two potential problems:
1. I’m skeptical the minimal gaskets will provide an effective seal.
2. If we need to pull down the fixture for maintenance (e.g. a defective driver, which is connected to the fixture, in the attic), we’ll disrupt the insulation above.
I understand that “top hats” can be installed. Simple covers that go over the fixtures in the attic, cut to pass the wiring through and are foam-sealed to the drywall / light frame / wiring. Rated for the purpose. The commercial products I’ve found so far – made by Tenmat (for example, https://www.tenmatusa.com/insulation-protection-covers/ff130e-recessed-light-draft-stop-cover/) – are pricey at $20 and up. These are round, appropriately named. (
For the fixtures we’re using, a rectangular cover would fit better, providing more room to separate the driver from the fixture. Our insulation contractor says they’ve had good luck making their own boxes using Thermoply, using foil tape to seal the joints. This seems like a good way to go. They can be fabricated to meet the size requirement and I believe Thermoply is an appropriate material from a fire-rating standpoint.
A box could also be made from drywall but harder to work with than Thermoply.
Any experience with this approach or other products / methods you’d recommend?
Thanks in advance.
Doug
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Bummer this wasn’t answered. I have the same question.
Standard GBA practice has been to "box over" can lights with rigid foam when you have access to them from above. XPS can work for this, as can polyiso. 1/2" foil faced polyiso and foil tape on the seams does a good job. You don't need a lot of R value for the box itself if it's going to be buried in loose fill insulation anyway.
Recently I've started to build the boxes with plywood and 2x2s, so that they can be stepped on without being damaged. I got the idea on here from one of the other members that boxes over bathroom fans, but it can work with lights too. All you need is an air sealed box, you can make it out of pretty much any materials you have on hand.
Those pre-made top hats are great for retrofit work, since some of them can be squished through the hole in the drywall so that they can be installed from below. They aren't cheap, but they save on labor.
I usually seal up the cans before installation with some foil tape over the seams and any holes. I don't trust the gaskets either (they're usually not even applied to the can correctly all the way around), but a little rope caulk makes a nice removeable seal if needed. If you air seal the box above, then the can itself doesn't really need to be air tight anymore. I think boxing the lights over is a better way to go, and it allows for pulling the can out (if you use "remodel" type cans) from below without disturbing the attic insulation.
Bill
I haven't used the Tenmat hats but they're the typical "green" solution. I, and the builders I work with, usually make our own from foil-faced polyiso. A few cuts, tape the corners and you're good to go. Just be sure to leave enough space that the fixtures won't overheat.