Tape 'em up.
So, a client has purchased a house. There are about 10 6" recessed lights installed. They went in about 20 years ago, would be my guess. (There was some newspaper stuffed in a wall to allow plaster to be applied, that and the look of the lights and the NM gets me pretty confident on this.)
I don't know if they are really insulation contact rated. They have thermostats in them, and they certainly are buried in insulation with a 65watt bulb in them, without any tendency to blink. And it is hot here just now.
What they certainly ARE NOT is air tight. The cans are just punched through with holes and slots.
They are new work, not retrofit, so I'm reluctant to just tear them out.
The client wants to retrofit with LED trims.
I'm wondering: of the 6 that we intend to keep (we don't like the placement of the others) can I just remove the three screws that hold them to their frames and drop them into the room (mechanically, yes, I can) and use aluminum duct tape to close up the various slots, then shove them back up into the attic?
I'm just looking to save the client a few bucks and me some time. He wants another 18 cans installed, got plenty of work to do.
The cans were UL tested and listed with holes and slots. Altering them in any way not consistent with their instructions and listing is illegal. You open yourself up to liability for anything that happens in the future.
The new air tite cans are the old cans with foil tape over the holes. Besides, there is nothing in the instructions that says anything about leaving the any of the holes open.
Unless the cans have “IC” marked on then the answer is no.
Install a “top hat” over the cans. This is a simple fix by framing around the can staying 3 inches away and covering the framing with sheetrock.
Burying a non-IC rated can light fixture in insulation is a code violation, but taping/caulking the holes isn't. The holes in fixtures are for convection cooling, and not a factor in the fire-ratings.
If you're installing a sub-15W LED assembly in there the fire risk is pretty close to zero even without a box-over. But if you have the space, taping up a cardboard box with housewrap tape (for longevity) that provides the code-prescribe 3" clearance, and air-sealing the box to the attic side of the gypsum with gypsum or can-foam would be code-complaint.
On any new fixtures, if they're not fully air-tight at the seams and gasketed it's OK (and desirable) to caulk them to be air tight for both space heating/cooling energy and moisture transfer reasons. A quarter of a square inch of air leakage at into an attic will move more moisture into the attic in winter than 2-sheets of vapor permeation through latex painted 4'x8' gypsum. With a 10W LED assembly in there, multiply that by more than 10 when the light's on. (With a 65W bulb it's much much higher still.) A typical non-air-tight can light will have about a square inch of leakage, even if you caulk the can to the gypsum under the trim (also recommended, even if it's a gasketed unit.)
I installed a mess of new cans today. Gotta cut closer to the template! I used quite a lot of painter's caulk to close the gap between the cans and the ceiling, and I will be covering ALL the holes in the cans before I install the LEDs.
Recessed lights are swell and all, but they sure do let a lot of dust drift down into the house if you give them a chance, and all the heat and moisture moving back and forth, bad.
Seal those things up.
What brand/type LEDs are you using?
I installed 25 of the CREE 6 inch retrofits in my home. The lenses are air-tight. Considered caulking them in place but didn't do it. I may reconsider and go back around to caulk them in.
Wasn't sure if it would be worth the effort but it sounds like it is.
I'm in a third floor condo with a crawl above. Until last year there was zero insulation in this 100 year old building. We had cellulose blown in last year. I'm pretty sure the guy missed some spots as the ceiling is raised in some spots (tray ceilings etc.).
I have 6 inch HALO housings - IC rated but NOT air-tite. I could strangle the electrician for not giving me the air-tite option ten years ago when he installed the housings.
But I think these monolithic lens/trim I have now will work - even better caulked in place. No?
The whole question of how and if to seal them is the point of this thread. LED s and their drivers don't throw off much heat. If your cans have thermostats in them and you keep them, they will be pretty safe.
I offer no advice or direction. However, calking the cans to the drywall and taping up the cans will stop the dust from drifting down.
But you should not do that, as it violates the original design of the equipment.
25 cans. Ouch. If it was six I'd tell you to put in new ones.