# Expanding foam for recessed lighting?



## InPhase277 (Feb 9, 2008)

integlikewhoa said:


> I'm installing some recessed lighting and I was woundering if I could better seal them with expanding foam from the attic side. They are IC or insulation contact remodel houseings by halo. Will this cause any problems? What can I do to seal them? Thanks JIM


I personally would not use the foam. You can get a gasket that fits the trim.


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## Termite (Apr 13, 2008)

InPhase277 said:


> I personally would not use the foam. You can get a gasket that fits the trim.


x2 :yes:


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## integlikewhoa (Dec 31, 2007)

Yea the gaskets I have seen, but there is alot of adjustment holes and other holes around the side of the can and its just not going to be sealed very well with only a gasket around the bottom of the ring.
Inside of the ring im sure I can put some silicone or calking around there and seal the can to the celing, but im more worried about air going around the bulb and threw the holes on metal can its self. 
It would be nice to wrap or seal it better with something. I have a wide open attic above the celing with good access to it. Do you guys have any other options?


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## InPhase277 (Feb 9, 2008)

integlikewhoa said:


> Yea the gaskets I have seen, but there is alot of adjustment holes and other holes around the side of the can and its just not going to be sealed very well with only a gasket around the bottom of the ring.
> Inside of the ring im sure I can put some silicone or calking around there and seal the can to the celing, but im more worried about air going around the bulb and threw the holes on metal can its self.
> It would be nice to wrap or seal it better with something. I have a wide open attic above the celing with good access to it. Do you guys have any other options?


The reality is that unless you have 500 cans, the amount of air that is leaking through is probably miniscule. I guess that if you just wanted to, you could silicone around the housing, but I would avoid the foam. What you also can do, is purchase the trims that allow for the socket to be clipped directly to the trim, instead of held by springs. I believe the can you linked will allow that. You just have to remove the metal plate that's held in by the wing nut. Where the socket attaches is another gasket. So, if you get those trims with a gasket on the bottom, then you should be pretty air tight without any adhesives.


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## Termite (Apr 13, 2008)

If it bothers you, consider building sheetrock boxes around the can lights. Foam's highly flammable, cans get mighty hot...Bad combination in my opinion.


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## pauln (Jun 24, 2008)

I agree the so-called airtight housings don't seem to be very air tight. If you put a light inside the can, it shines through the seams. According to the manufacturer, it actually needs to leak in order to keep from overheating (!?). Strange design...

For new construction, you can get plastic buckets that you put over the housing and seal to the ceiling drywall. The buckets are apparently large enough that the extra air volume allows for heat dissipation without leakage into the surrounding insulation. These don't work very well for retrofits, however - pretty difficult/impossible to get the bucket in placed and sealed properly.

I'm planning to seal the housing seams with metal tape, then put a bucket over the housing, but not try to seal the edges of the bucket, assuming that the extra air volume provided by the bucket would allow sufficient additional heat dissipation to prevent overheating.

Is this worth the effort? Opinions seem to vary. The spec for airtight housings is 2 cfm leakage at 75 Pa. That sounds like a lot, but I don't know what it amounts to in an actual installed fixture. The fact that they make these buckets seems to suggest that it's an issue.


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## InPhase277 (Feb 9, 2008)

pauln said:


> The fact that they make these buckets seems to suggest that it's an issue.


The fact that they make these buckets seems to suggest that they want to sell it to you as an issue...


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## 220/221 (Oct 9, 2007)

Get a roll of that thin *metal* duct tape and cover all the holes in the can from the outside (except the installation clip sluts). Then, once installed, cover the clip slots from the inside..

The gaskets provided on the "air tite" cans are not very effective.


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## Piedmont (Nov 1, 2007)

Although expanding foam will likely work (it's self extinguishing and often used as a fireblocking material... I think other posters are referring to the XPS and EPS (eXtruded and Expanding polystyrene which is very flammable). I recommend putting flame to a piece of polyurethane expanding foam such as the stuff coming out of "Great Stuff" on fire, I've tried, the second you pull the flame away the fire goes out. They even make a fireblocking expanding polyurethane foam. Oh, that's when it's completely dry, until dry it is extremely flammable especially the fumes! Some construction workers working on a condo in the next town over were smoking while applying it, and burned the whole condo down!

There is a condition with polyurethane expanding foam that defeats its self extinguishing ability. That is, if you torch a hole into a block of it, you basically have made an oven that will cause it to burn. That is, the heat from the flame inside the hole will reflect to the foam and has no place to go it will be reflected back at the flame causing the flame to get more intense and reflect back to the foam and, rinse and repeat until there is an insane amount of heat and the foam will catch and stay on fire in that situation. It's not possible to have it catch on fire by applying a match or flame to the surface of it unless you keep the flame on it.

I recommend another route anyway. Air tight cans are pretty useless, but Home Depot sells Commercial Electric air tight inserts which look like a cone, they have a gasket at the top where the wires come in and around the base and those things are surprisingly almost if not completely air tight particularly combined with IC air tight fixtures. I use them everywhere I can. You can use Commercial Electric air tight baffles inside Halo IC cans. They are by the best way to minimize air leakage. Here's a picture.


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## pauln (Jun 24, 2008)

Piedmont said:


> Air tight cans are pretty useless, but Home Depot sells Commercial Electric air tight inserts which look like a cone, they have a gasket at the top where the wires come in and around the base and those things are surprisingly almost if not completely air tight particularly combined with IC air tight fixtures. I use them everywhere I can. You can use Commercial Electric air tight baffles inside Halo IC cans. They are by the best way to minimize air leakage. Here's a picture.


Looks interesting. Do these fit inside cans made by other manufacturers? There doesn't seem to be much information about them on the web.

Thanks,
Paul N.


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## pauln (Jun 24, 2008)

InPhase277 said:


> The fact that they make these buckets seems to suggest that they want to sell it to you as an issue...


They don't promote them - they make these because they are apparently required in new construction in Ontario.

Paul N.


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## moyerles (Mar 3, 2009)

*Help finding baffle*

Piedmont, could you provide a link to the Commercial Electric baffle you posted about? I've looked on the Home Depot website and can't figure out which one I need. None of the photos look like what you posted and I can't figure it out by reading all the descriptions.


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## Bob Mariani (Dec 1, 2008)

> Although expanding foam will likely work (it's self extinguishing and often used as a fire blocking material..


this is incorrect. Even Great Stuff makes a different foam for fire blocking. It is orange. Unfortunately many people do it wrong and even some propagate these ideas.

These holes are there for a reason. Do not directly block them. Foam boxes are made or make your own with drywall as suggested. Still need some room around for the lamps to breathe.


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## tedsan (Mar 4, 2009)

The canned foams that are rated for fire are orange so that building inspectors can see them more clearly. Chemically they are the same as the normally sold products. I had a length discussion with one of the manufacturers about this. And, since they had to pay for government testing and certification of "a product", they make a special one dedicated for this market. But otherwise, the products are claimed to be the same.

However, since every manufacturer has these products, you may as well use the stuff that's "approved" so as to avoid problems down the line.

Dow's Great Stuff 
DAP's comparable product
Handi-foam fireblock

NOTE: to clarify - *NOT *all foams are fireblocks! There are a variety of formulations, some burn, some don't. If you're tempted to use one that is not orange, fireblock rated, then at least try to set it afire under controlled conditions just to make sure the stuff you're using isn't the type that goes "poof!" 
I also talked with the rep from Halo, one of the largest recessed light manufacturers, about various cans, air leakage, etc. an he said there's no problem with sealing up the fixtures if they're rated IC. The problem, he stated, was that people don't pay attention to the labels in the lights that show where you adjust the fixtures for various bulb styles and wattages. If you look closely, the larger the wattage, the more you have to adjust the bulb holder down, allowing it to dissipate more heat into the room. newer fixtures don't seem to have this adjustment, but have just a wattage limit.

Also, the other problem, he stated, was that you need to ensure your wiring is 90C rated. Older wire was 60C rated, and that presents a fire hazard that must be dealt with.

By the way, 2CFM at 75Pa is quite good. 75 Pascals is a high pressure. We do blower door tests of homes for leakage at 50 Pascals, and conventional fixtures leak a heck of a lot at that pressure. The key thing is to install them correctly. You have to caulk the perimeter of the fixture to the ceiling in order for it really to be close to air tight. Most installers skip this step and rely on the poor foam gasket to do the job, which it doesn't.

By the way, the same thing applies to your HVAC ceiling/wall/floor registers. Make sure the boot (the part attached to your duct and the ceiling) is caulked or foamed do the ceiling to make that connection air-tight. Otherwise, you're leaking a lot of warm moist air (in the winter) into the attic/walls/floor cavities where it leads to significant energy loss and possibly causes moisture problems.


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## Termite (Apr 13, 2008)

Piedmont said:


> Although expanding foam will likely work (it's self extinguishing and often used as a fireblocking material... I think other posters are referring to the XPS and EPS (eXtruded and Expanding polystyrene which is very flammable). I recommend putting flame to a piece of polyurethane expanding foam such as the stuff coming out of "Great Stuff" on fire, I've tried, the second you pull the flame away the fire goes out.


Doesn't look like it burns to me. :huh:
The fireblocking foam is on the left, regular great stuff on the right.


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## Bob Mariani (Dec 1, 2008)

I thought that fire blocking was to seal air flow between a chase in which fire can spread. Wood blocking is ofter used. This burns also.


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## INDixie (Oct 30, 2009)

The model number for the trim is T49 Airtight Baffle Trim which is made by Commercial Electric (Home Depot store brand, I guess). I purchased this trim to make my old cans more air tight. I just saw your post today, hope this is not too late to be of help to you!


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## moyerles (Mar 3, 2009)

*Use Compact Florescents in Your Can Lights, Then Foam Them*



INDixie said:


> The model number for the trim is T49 Airtight Baffle Trim which is made by Commercial Electric (Home Depot store brand, I guess). I purchased this trim to make my old cans more air tight. I just saw your post today, hope this is not too late to be of help to you!



It was too late, but that's Ok--I improvised. Once I got up in the attic and really started messing around, I realized the cans were mounted too close to the rafters to add any sort of baffle to them anyway. Here's what we did....

First, I disagree with the person who said that the holes are small and can't make that much of a difference. If you add up the space of ALL of the holes in the can and imagine drilling a single hole in the side of your wall that (combined) size, it's a BIG hole. The previous owners of our house put in 26 can lights in the great room of our house. So multiply that hole size by 26 and it's like leaving a window open! In order for the electrician to install them, they removed the insulation over ALL of those lights so that about 500 square feet of our primary living space has NO insulation AT ALL. (Black asphalt shingles in Oklahoma--hot in the summer, cold in the winter. Argh!) In addition, we have loose cellulose and chopped fiberglass (fiberglass was NOT MY CHOICE--it was here when we moved here) in the attic and I didn't like the idea of dust coming down through those holes either.

So, our solution..... The can lights are "IC" lights. I inquired at the lighting store and they said that as long as the lights had 75 watt or less bulbs in them, they were fine to have insulation right up against them. So we removed all of the existing flood light bulbs and replaced them with 15 watt (I think--maybe less) compact florescent flood light bulbs. We will ALWAYS keep compact florescent bulbs in them (and we have no plans to move in the next 25 years--this is our retirement farm). Then I went into the attic and sprayed a can (one per light) of expanding Great Foam over each can light, sealing up all holes. 

This solution might not appeal to everyone, but I think it's fine for us. We have a longer-term plan that involves eventually replacing most of those lights and even insulating our attic differently so that the air leaks wouldn't matter (insulating the roof of the attic vs. the floor of the attic). If these can lights are still here when we sell the house, we'll tell the new owners to keep low wattage bulbs in them.

We made this change several months ago and have had no problems with overheating, lights burning out, etc. I bought the foam on sale, making this an inexpensive solution.


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## Bob Mariani (Dec 1, 2008)

An IC rated can can be sealed as you suggested (I do it all the time) and still use a regular bulb without overheating issues. The reason you use these cans is so you can insulate against them. The foam is the correct way to air seal the ceiling penetration and is done as a normal weatherization project.


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## geonovice (Jan 13, 2010)

HI, I'm new to this forum, this is my first post. Recently while at Home Depot I asked what they had to insulate my ceiling pot lights. One of the "Orange apron guys" showed me some of the "new build" light fixtures. These fixtures had little squares of grey tape on the outside of the cans, over the holes. The tape was a little bit thicker than regular electrical tape. In addition, any of these type of lights that I have seen have a thermostatic device inside the can to turn the light off if it gets too hot. I was going to just use the metal tape that is used on A/C ducts to seal up the outside of the cans, & as someone suggested earlier in this thread, use low wattage bulbs or CFL's in the ones that don't have dimmers.


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## rperry2394 (Dec 23, 2009)

geonovice said:


> HI, I'm new to this forum, this is my first post. Recently while at Home Depot I asked what they had to insulate my ceiling pot lights. One of the "Orange apron guys" showed me some of the "new build" light fixtures. These fixtures had little squares of grey tape on the outside of the cans, over the holes. The tape was a little bit thicker than regular electrical tape. In addition, any of these type of lights that I have seen have a thermostatic device inside the can to turn the light off if it gets too hot. I was going to just use the metal tape that is used on A/C ducts to seal up the outside of the cans, & as someone suggested earlier in this thread, use low wattage bulbs or CFL's in the ones that don't have dimmers.


I'll have to check those out. When I put cans in my bedroom, I wasn't too worried about escaping heat as I think a house should breath a bit anyway. A tightly sealed house is more energy efficient and more likely to make you ill - especially when someone in the house is already sick.


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## moyerles (Mar 3, 2009)

*Energy Efficiency vs. Air Quality is a False Dichotomy*



rperry2394 said:


> A tightly sealed house is more energy efficient and more likely to make you ill - especially when someone in the house is already sick.


This is a false dichotomy. One doesn't have to choose EITHER energy efficiency OR good indoor air quality. An energy efficient house that is built well--built properly--will also have good indoor air quality. An intentionally drafty house isn't smart--no matter what your justification--and certainly not best for sick people. Instead, the smart choice is to build a super-tight, energy efficient house and install an HRV or an ERV so that you're bringing a measured, appropriate amount of air into the house and, in the case of the HRV, that you're not losing energy in the process. 

Another factor is to watch what pollutants you bring into the house in the first place--in cabinetry, furniture, carpeting, cleaning products, paints and varnishes, etc., so that you're not dirtying the air any more than necessary.

--Leslie


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## moyerles (Mar 3, 2009)

*Thank you!!*



Bob Mariani said:


> An IC rated can can be sealed as you suggested (I do it all the time) and still use a regular bulb without overheating issues. The reason you use these cans is so you can insulate against them. The foam is the correct way to air seal the ceiling penetration and is done as a normal weatherization project.


Thanks so much!! You have no idea how many people I asked about this and never could get anyone to give me a firm answer about this. Everyone seemed to be covering their behinds and reluctant to give me a straight answer on this. 

--Leslie


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