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MLV instead of backer box

603 Views 2 Replies 3 Participants Last post by  BIGmouthinDC

I am using canless LEDs in my basement which I am soundproofing as best I can. My plan was to make backer boxes hung from the channel. I just had an idea which would save some time and was wondering if anyone had tried it or had an opinion on how it would work.

The hinge of the clips of the light are 1.25" from the front light baffle and so the clips should sit flush on the top layer of drywall. The idea is to make a 12" x 12" square of dynamat (2 layers thick) and lay it on top of the hole in the drywall. I would then caulk the 1/4" hole for the cable thay connects the light to the LED driver/J-box. I should be able to put the cable through the hole in the dynamat and then roll it up and push it through the 6" drywall hole for the light. I would then pull off the paper and lay it flat on the drywall. The weight and adhesive should (hopefully) be enough to create a good seal.

A picture of the light is attached. It is a Juno Wafer Downlight-Canless.

Thanks for any input.


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You could also just add two 12x12" layers of sheetrock added to the back of the 2 surface layers and save a bunch of $. I don't know that dynamat is fire code for such an application. I like it on my ductwork, but not the back if my electric.
The Heat shouldn't be an issue with the Dynamat as it can survive in tight engine spaces and has a high temp rating and those LED lights are nothing. It meets the federal standard for car interior surfaces and can withstand up to 300 degrees F. I don't think it has ever received any certifications for residential construction but their website shows many home uses.

another option I have stuck putty pads to halogen light fixtures when I didn't have room for backer boxes and they did just fine from a thermal perspective. That was before the proliferation of MR16 GU10 LED bulbs. Putty pads do have a fire rating.
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