Soundproof Recessed Light Boxes

Not familiar with that exact light, but you use the spreader bars to hold the can in the box. Typically the inside of the recessed light can be adjusted up or down. You loosen a few screws and the inside cylinder will slide up or down to adjust for ceiling thickness.

I'm not sure why you would remove the spreader bars? The other option is use remodel cans and install them after the GWB is installed.

Tim

I like putting backer boxes in the ceiling with the romex coiled inside. Later after the drywall is up you drill a hole (hole saw) for a remodel recessed can and install it. You just need to do some really careful measuring. Don't forget to put a big bead of acoustical caulk on the lip of the box before you raise the drywall. A remodel can is designed to fit through a hole. It does have a longer tail which you need to plan for in the size of the box.

I'm doing the same thing you're doing by using NC cans instead of RC cans (basically because I got a good deal on them). I think what you're asking is how to secure the actual can to the box, correct? What I'm doing is attaching the box to the joist (with either GG and screws, or extra clips I might have laying around), running my romex to the box, and then installing the can in the box using screws. I'll pre-drill through the MDF and use some metal self-tapping screws to get into the sides of the light. On the ones I'm using, there is a nice "faceplate" so-to-speak that I can drive a screw threw to secure. As you mentioned, the first layer of DW will really secure it. I'm not quite at that stage yet, but will be shortly and can upload some pics.

a hard connection between the backer box and the joists will defeat any kind of ceiling isolation you might have used, like clips and channel. Recently I just hung the boxes off of the channel with a couple of 1x2s (screwed to the channel. You can also see the WIDE edge I added to the box to give a landing zone for the huge helping of acoustical sealant.

Here's how we did my can lights so many years ago, 2005.
What you can't see is that we allowed a bit of "float" with the RSIC clips to ensure a good seal, used red fire type caulk on the Romex holes to the mdf boxes and then used Green Glue and drywall on the outside of the boxes.
When the first layer of drywall was hung, a bead of acoustic caulk was applied to the bottom of the box.
There were for 4" IC can lights with very adjustable trim.
The original X supports were replaced with solid wood glued and screwed supports to ease hanging the Roxul. We were learning as we went. Sort of.


Edited by Milt99 - 9/18/12 at 7:21pm

Thanks for the pic - that will make my install go so much more smoothly than I originally planned.

I like all the pics. Some info here also: http://www.soundproofingcompany.com/soundproofing-installation-manuals/sim-backer-box/

I made boxes with 1/2" MDF and left over 5/8" DW and they seem sooo heavy. Will the clips channel be able to support them AND 2 layers of 5/8" DW this way?
Edited by blipszyc - 10/20/12 at 12:39pm

I might suggest that if there's a small point load addition like a heavy backer box, that you get another clip or two in that area. Like 1 added clip per channel right where they can help accommodate the small added load.

Sounds good. Thanks for the quick reply.

Nice pics. In my setup, I have 9" high by 14" wide space between my ceiling joists. I am planning at LEAST DD + GG for the celing and probably furring/sound clip. With my joist cavities would a backer box for a 6" can light be enough space or would a 4" can light be the only way to go. Mr. White I looked at your diagram closely and am wondering if i have sufficient space in my joist cavities for a backer box. Thank you.

Looking at the specs, the fixture is 7 1/8" tall. If using clips and channels, that will essentially increase the cavity depth by 2 1/2", assuming double 5/8" drywall. So the fixture gets dropped by that amount. So now you're at ~11 1/2" available cavity depth, so you have room height-wise.

You will have to trim the extension arms of the fixture to fit in the backer box.

Excellent thank you. Yes i am using DD+GG along with the channels and clips. Does the backer box get flush with the first or second layer of drywall(first being the piece attatched to the channels)

Usually, backer boxes sort of rest on top of the first layer of drywall.

BUT, can the backer box be flush with the first layer, and rest only on the second layer? The reason I ask is that I am using IC 4" cans, and the lip is only made for a single layer of DW.

You can do that. Make the bottom hole smaller than the upper hole to accomplish.

Thanks Ted. Only thing is that I am using these. I guess make the opening just large enough for the housing....

NOOOOOOOO. First take a close look at the can most of that design have an inner sleeve that slips down to accommodate thicker ceilings. If not you can often still attach the baffle even if the lip is 5/8 recessed. You are making way too much work for yourself.

^^what he said. They are adjustable. Mount the housing (housing, not lip) flush with the joists. Apply 2x GWB. Use cutout tool to expose 4" opening. Use screwdriver to loosen sleeve, pull sleeve down flush with GWB.

Even the old work cans will work up to 1-1/8".. speaking from experience.