How would you keep cellulose off of these lights?

stm317 · Sep 11, 2017

Hey everyone, I'll be blowing in some cellulose insulation above my ceiling in the next couple of months. I've installed LED troffer lights (2ft x 4ft), and I'd like to keep the cellulose from sitting directly on top of the lights, or possibly falling through any small gaps. I still want to retain as much R-value as possible since the lights have such a large area, so I'll probably blow the cellulose on top of whatever solution I come up with. I've considered making hinged panels out of Tyvek or foam board that could be attached to the framing around the lights. Anyone have any other helpful tips or ideas? Any materials to specifically stay away from? If I end up doing a hinged panel, should I include a vapor barrier on the underside of the panels? (I'll have a vapor barrier on the rest of the ceiling)

Here's a pic to shed a little light on the situation:

https://scontent-ort2-1.**.fbcdn.net/v/t31.0-8/20507295_10103055840767674_4959884492121106213_o.jpg?oh=b1db97167dc128817e41e75015c71a87&oe=5A38446C

850xpeps · Sep 11, 2017

Well if they aren't sealed you should have poly behind them anyway. Poly first then install lights. If you don't poly behind the light you will have condensation inside them.

stm317 · Sep 11, 2017

850xpeps said:
Well if they aren't sealed you should have poly behind them anyway. Poly first then install lights. If you don't poly behind the light you will have condensation inside them.

Thanks. I will plan on doing a vapor barrier above the lights.

The easiest way to do that is to just nail or staple it to the framing around each light fixture, but these lights need to be lifted up and turned slightly in order to be removed or worked on. If I had vapor barrier permanently fixed above each fixture, then I would lose the ability to maneuver the lights enough to remove them if necessary. So, I'm trying to come up with a sensible way to keep the insulation from resting directly on top of the lights, while also retaining the R-Value and the ability to remove the lights if necessary down the line.

matt_i · Sep 11, 2017

I would build a "box" out of pink foam boards, even using 16d nails as "pins". Tape all of the seams with Carlisle 1402 mastic tape to seal it up. Could also be plywood too, screw and glue. Then just flow the insulation over the top.

sberry · Sep 11, 2017

Seems surface mounting them would be way better?

850xpeps · Sep 11, 2017

Ya build a plywood box. Poly on the cold side of it and tape the other ceiling poly to it to seal it up.

LX-Markham · Sep 11, 2017

matt_i said:
I would build a "box" out of pink foam boards, even using 16d nails as "pins". Tape all of the seams with Carlisle 1402 mastic tape to seal it up. Could also be plywood too, screw and glue. Then just flow the insulation over the top.

like a home-made version of these?

https://www.tenmatusa.com/fire-rated-troffer-covers/ff130-2x4-troffer-cover/

LXCam · Sep 11, 2017

The determining factors needs to be if they are rated for direct contact with insulation. If they aren't you need to look up what's required for clearance.

stm317 · Sep 11, 2017

LX-Markham said:
like a home-made version of these?

https://www.tenmatusa.com/fire-rated-troffer-covers/ff130-2x4-troffer-cover/

That's perfect! Too bad they're $90+/piece... I'm pretty sure I can come up with something similar though using some of the other suggestions though. Thanks for the visual!

Stuart in MN · Sep 11, 2017

LXCam said:
The determining factors needs to be if they are rated for direct contact with insulation. If they aren't you need to look up what's required for clearance.

This.

Find out if they can be installed with direct contact to the insulation before doing anything.

stm317 · Sep 11, 2017

Since it's been mentioned a couple of times, the lights do not need to be rated for direct contact with insulation. Whatever I end up building will be used to prevent direct contact with insulation, and minimum required clearance will be upheld.

That being said, they're decently efficient LED panels that are half an inch thick. They create little heat, and take up very little space, so I should have plenty of clearance for whatever is spec'd.

Brian_WK · Sep 11, 2017

Poly foam board. I would use spray glue 3M Foam Fast 74 to adhere them together then aluminum tape the seams.

Brian

stm317 · Nov 13, 2017

So, finally getting around to this project. I got a deal on some foil faced, 1/2 inch polyiso foam boards that I'll use to make box lids that cover the lights. The plan, is to leave a substantial air gap of several inches between the backside of the lights and the foam.

Now, my question for you folks is which side should I put the foil on? Normally, the foil would go to the warm side so that it will reflect heat into the insulated space. However, is it a good idea to reflect heat back onto the LED panels? They don't get super warm, but I don't want to do anything that might damage them or shorten their lifespan. What say you?

BADSIX · Nov 13, 2017

what I would have done is to use foil backed bat insulation and laid it foil down over the lights then shoot the cellulose over and around it.
Jay D.

Lelandwelds · Nov 13, 2017

stm317 said:
So, finally getting around to this project. I got a deal on some foil faced, 1/2 inch polyiso foam boards that I'll use to make box lids that cover the lights. The plan, is to leave a substantial air gap of several inches between the backside of the lights and the foam.

Now, my question for you folks is which side should I put the foil on? Normally, the foil would go to the warm side so that it will reflect heat into the insulated space. However, is it a good idea to reflect heat back onto the LED panels? They don't get super warm, but I don't want to do anything that might damage them or shorten their lifespan. What say you?

Foil needs an air gap to reflect light or heat.

Lots of garages get wet spray cellulose stuck to underside of roof deck and walls. You could use netting and blow behind it. Build a box with rigid foam or sheet rock. Use silver foil tape not spray glue. Use cardboard dams before or after blowing.

stm317 · Nov 13, 2017

Thanks for the advice so far. It seems like I haven't given enough info and it might be leading to some confusion. I'm sorry if that's the case. So, some more details about the long term plan might help clear things up. Once the lids are done and installed:
1. Soffit baffles will be installed
2. The bottom chord of the trusses will get a vapor barrier nailed to it.
3. Cellulose will be blown in on top of the vapor barrier to the appropriate depth (16 inches or so)
4. The ceiling will be finished in white metal

These lights are designed for drop ceilings in office buildings, etc so they rest in a framework and pretty much just sit there. If they ever need to be removed for anything, they have to be lifted up, tilted, and dropped out of the center of the frames. So, my goal with these lids is not only to keep the cellulose from resting directly on top of the lights, but also to give me a little bit of working room to lift and tilt the panels without being covered in cellulose should the lights ever need to come out.

stm317 · Nov 15, 2017

So, after some reading, I think I've decided to place the foil face of the insulation away from the LED lights, rather than facing down into the insulated space.

Higher ambient temps can shorten LED lifespans according to this article: http://www.lrc.rpi.edu/programs/nlpip/lightinganswers/led/heat.asp

Jlbc212 · Nov 15, 2017

As a firefighter in an old mill city with wood frame housing that was built before electricity in houses was existent, I must have gone to at least six structure fires every year involving cellulose insulation in combination with metal sheathed wiring (BX cable). These houses where fitted with "knob and tube" wiring after electricity became available. Later BX cable supplemented or replaced the knob and tube wiring. The need for insulation didn't occur until heating fuel prices skyrocketed in the early 70's. The BX cable lacked a good ground. Any breakdown of wiring insulation could potentially make the outer metal sheathing a conductor of electricity. Being a poor conductor it will heat up. Place cellulose insulation over it and you have all the makings for a fire. Supposedly cellulose insulation (recycled newspaper) is treated to make it "fire retardant." Does any industry watch group actually check, test and certify the fire treatment process? From my experience IMHO I wouldn't use cellulose insulation anywhere near anything that could potentially produce heat. There are other much safer insulation products that are readily available.

NUTTSGT · Nov 15, 2017

You have the insulation panels. I would just simply make a box by screwing the panels to the outside of the light framework you already have in place. Once you have the four side walls, cut another piece as a top to slide inside the box as a cover. Then blow cellulose over the entire thing.

As far as screws go, I'd use nothing more than some drywall screws with either fender washers or rob the plastic caps off some plastic capped roofing nails.

stm317 · Nov 15, 2017

Jlbc212 said:
As a firefighter in an old mill city with wood frame housing that was built before electricity in houses was existent, I must have gone to at least six structure fires every year involving cellulose insulation in combination with metal sheathed wiring (BX cable). These houses where fitted with "knob and tube" wiring after electricity became available. Later BX cable supplemented or replaced the knob and tube wiring. The need for insulation didn't occur until heating fuel prices skyrocketed in the early 70's. The BX cable lacked a good ground. Any breakdown of wiring insulation could potentially make the outer metal sheathing a conductor of electricity. Being a poor conductor it will heat up. Place cellulose insulation over it and you have all the makings for a fire. Supposedly cellulose insulation (recycled newspaper) is treated to make it "fire retardant." Does any industry watch group actually check, test and certify the fire treatment process? From my experience IMHO I wouldn't use cellulose insulation anywhere near anything that could potentially produce heat. There are other much safer insulation products that are readily available.

Thanks for the suggestion. I'm confident that cellulose won't be a fire risk for me. The LED lights produce some heat, but it's far less than traditional incandescent lights, and with these boxes over the lights, I'll have a layer of insulation in between the lights and cellulose. The wiring is all brand new romex, installed by professionals. People smarter than me have deemed it safe enough to be used in nearly every new house including ones insulated with cellulose.

The big benefits to me, are R value and cost. I'm on the edge of climate zone 5, so attic space should be insulated between R40-R60, and I haven't found a cost effective way to do that without cellulose.

NUTTSGT said:
You have the insulation panels. I would just simply make a box by screwing the panels to the outside of the light framework you already have in place. Once you have the four side walls, cut another piece as a top to slide inside the box as a cover. Then blow cellulose over the entire thing.

As far as screws go, I'd use nothing more than some drywall screws with either fender washers or rob the plastic caps off some plastic capped roofing nails.

That's basically the plan, although instead of screws I might use button cap nails to 'pin' the box together and then tape the seams with foil tape, just because I already have them sitting around.

NUTTSGT · Nov 15, 2017

stm317 said:
That's basically the plan, although instead of screws I might use button cap nails to 'pin' the box together and then tape the seams with foil tape, just because I already have them sitting around.

Use the screws to screw the foam to the wood of the frames that hold the lights. Then use you plastic cap nails for the corners and tape.

Honestly, I don't think it matters what you do, that **** (cellulose) will get into it.

stm317 · Nov 16, 2017

NUTTSGT said:
Honestly, I don't think it matters what you do, that **** (cellulose) will get into it.

I know the chances of keeping all of the cellulose out are slim. I'll have to have a small slot an inch or 2 long in the side panels for the romex to pass through. I'm just trying to keep 95% of the cellulose where it's supposed to be. I started working on them last night. Lots of trial and error climbing up and down the scaffold, but it will get easier once I have the first one completed and can use it as a template.

Platonic Solid · Nov 16, 2017

Can't you just put a flat piece of insulation board on top of the wood frame you already have and be done with it?

stm317 · Nov 16, 2017

Yes. That would achieve the goal of keeping the insulation off of the lights. I'd prefer to have a bit more height though to hopefully allow the lights to be removed without disturbing the insulation.

My current design has 9.5 inches of height, but slips down over the wooden framework. This means I have about 9 inches of working room beneath the lids when installed, and they can be slide up 3.5 inches higher (12.5 inches total working height) without coming off of the wood framing and letting a bunch of the insulation fall below.

Platonic Solid · Nov 16, 2017

You'd have no insulation mess issues if you put flat insulation board right on the wood frame and design a way to remove the fixtures from the room side.

stm317 · Nov 16, 2017

Maybe I'll try that next time I install panels. For this project, the mounting is done, the lights are installed, I've purchased the material needed, and begun the fabrication. Redesigning the mounts with tabs or something that would allow the lights to drop out the bottom isn't super appealing at this point.

Is there a readily available product that would allow that? Every troffer light I've ever messed with had to be lifted out of the framework before dropping it down.

Brandonorr55 · Nov 16, 2017

Some pet food and feed stores sell disposable cat litter boxes that look identical to your picture. Good luck!

Platonic Solid · Nov 17, 2017

stm317 - I can think of many ways to accomplish room side removal, but not sure if they would work at this stage or with your particular fixture.
First thought: depending on weight and fixture design, I could imagine 4 to 6 torsion springs holding the fixture in place, as used on many smaller can fixtures. The clips would need something on the fixture to attach to and something on the wood frame to clip into.

sgfarm · Nov 18, 2017

Not sure if it too late or not, but here is my $0.02.

Build your box out of drywall. Cheap, easy to work with, very heat resistant. Slice through one side paper and hinge it around the other paper face then tape the joint to hold it roughly in place. No fire risk, poly and insulation above and away you go.

Mike

How would you keep cellulose off of these lights?

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