surface-mounting dense fiberglass batts

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  #1  
Old 05-22-16, 09:46 AM
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Question surface-mounting dense fiberglass batts

My first post to this forum, hoping for great ideas!

We have a daylight basement that looks like the 60's puked all over the place and we're trying to start redoing. Half of the main room (whole room is about 18' x 25', so this is about 18' x 12') is being redone as a TV area, the other half will have a pool table and gas fireplace.

Anyways, we just 'inherited' about 350 sq ft of 2" high-density fiberglass batts. They're all 4' x 8', no vapor barrier, but one side is black (the rest is yellow). They were surface-mounted to be a band-practice area and I'm hoping to surface-mount (currently has un-mudded drywall hanging) again in the basement. Someday, I will pull the walls off, do some seismic retrofitting and put the fiberglass behind the (new) drywall, but this is not that day.

So I'm looking for a reasonably secure way to hang these pieces ON TOP of the drywall in a way that I can take them off in a few years without destroying them (so I can hang them in the framing cavities later). these cost about $1.5/sq ft new, so it's important I don't have to destroy them when I take them off.

Any thoughts? I'm thinking about using upholstry tack strips (sort of like this), but not sure the 'grip' is deep enough.

Thanks in advance!
 

Last edited by burningbaal; 05-22-16 at 10:08 AM. Reason: added link
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  #2  
Old 05-22-16, 10:43 AM
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The compressed panels offer about R3, I believe, so you won't be getting much insulation for the buck so to speak. They are made for sound control more than insulation, which I think you allude to in your post.

Is your basement totally below grade, or is it a walkout? Hanging them to protect them will be a trick to say the least. I would just drive 3" decking screws in all 4 corners and in the middle of the long dimension directly to the sheetrock. You will be hitting a stud so it should stay.
 
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Old 05-22-16, 12:09 PM
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If I'm getting this right, you want to install the 2" of HD fiberglass insulation directly against the drywall. The question I have is, what is on the other side of the drywall. I assume the foundation, but is there any insulation. Leaving the fiberglass insulation exposed creates a problem is the surface of the drywall will cool below the dew point. To avoid that they usually (climate dependent) want an equal r-value between the drywall and the outside.

Even with the black surface to the inside there will be moist air seeping in through that layer and reaching the drywall.

Bud
 
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Old 05-22-16, 01:59 PM
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thanks for the replies. This is primarily for sound, not just for heat. these will go on walls that are under grade, I don't think there is any insulation behind the walls now (there's one gap on each wall I can look and I don't see any insulation there), so moisture on the drywall-side could be an issue potentially.

I suppose I could use 3" screws, but not sure they'd really support the weight of the batt unless I used a ton of them, even in a stud, I'm worried the fibers would just tear around the screw. sure would be easy, though...

Perhaps I should think about some way to create a vapor barrier without ruining the aesthetics I kinda like the matte-black face.

And just to be clear: primary purpose is to help the acoustics for the media room and pool table.
 
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Old 05-22-16, 02:13 PM
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Can you explain why you would put the panels behind the drywall upon remodel? That is the premise that I took that you were looking at insulative qualities. For sound deadening, I would cover the panels in burlap or other heavy fabric and hang them with hidden cleat type clips on the walls. You would need a more aggressive type hanger than the one you showed, however. You could also adhere the panels to the sheetrock using something like PL8x or equivalent, and eliminate the mechanical fasteners. I have done it with Homasote panels, which are more degradable than the fiberglas panels you have and it works well.
 
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Old 05-22-16, 07:27 PM
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I did a little more digging online after the recommendation for hidden cleats and found these impaling clips that may work for me. I thought about a construction adhesive (@Chandler), but expect it would tear apart the backs of them when we take it down.

I guess I'm a bit TBD about if I'll put them behind the drywall in the future, so I'm not too worried about that yet, but I know I'll need to take them down to do the seismic retrofitting and I want to put them back up (one way or the other...)

I also thought about covering it in stretched burlap, but not I'm thinking those clips (linked above) would be best.
 
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Old 05-29-16, 08:07 AM
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I've got my plan, I'll post it here for future reference, and I'll try to remember to add pictures once it's done
I'm going to cut the batts just the right height so they are snug between the wall/floor (and on the left/right). Then we'll cover it in felt. We bought wide-bolt felt so the bottom 5 ft will be light gray, the tops will be white.

This will allow us to wrap the felt around the cutouts for the outlets and such, so none of the yellow will be visible and it will keep the fiberglass a little less itchy

we'll anchor the felt on the sides with a strip of lath and some nails to make sure the felt doesn't tear out of small staples.

In-progress (you can also see the new front door in the middle of being finished):
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In other news, we're shifted plans from doing 2 walls to doing 1 wall and part of the ceiling (until the soffit, as it turns out).
Ceiling plan:

same lath, spray painted black, hold the batts up while screwing the lath up with 3" drywall screws. we'll start with 3 pieces of lathe on each batt , one on each end and one in the middle, plus two more if it needs them. the 3" screws should be enough to go through the lath and batt and bite into the drywall ceiling without crushing the batts.
 
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