# batt vs blow-in insulation



## 22bandit (Sep 12, 2011)

Hey everyone,

Im am almost ready to start drywall on my bar/theater budget build and have a quick question. Does anyone have a recomendation for using batts in the ceiling vs stapeling a layer of fabric to the ceiling joists and using blow-in insulation? I have a few places with ducts etc. that would make using batts difficult plus i think blowing it in would be much more easy.


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## ironglen (Mar 4, 2009)

Will you diy? I can tell you that blow-in can be messy, both greenfiber (cellolose) or fiberglass. I used greenfiber in my attic and it was extremely dusty, but the attic passes sounds much less into the house as it is quite dense compared to fiberglass. I also found that to have a pro come in wasn't much more than diy, even with a sale price on the insulation, so 4-5hrs in the attic vs the pro in 30min: I told my friend to ante up the extra $80 and have it done. He was really happy, especially since he mentioned it looked thin, so the guy blow extra up there :T


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## 22bandit (Sep 12, 2011)

i was planning to do it myself with the free blower rental you get when you purchase the insulation. The mess isnt too much of an issue as drywalling will follow right behind it and cause a decent mess on its own. My biggest concern is cost as im in the military and will prob be forced to move again in a couple years.


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## SAC (Dec 3, 2009)

May one ask for what purpose you are doing this?

Just a note, as if you are attempting to isolate the floor above the room with isolation/sound transmission, this will not be effective.


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## bpape (Sep 14, 2006)

Agreed. There are 2 different considerations here. If you don't put up drywall, you seriously compromise isolation by not having the layer of mass. 

The other problem with just cloth and fluffy or blown in over that large an area is that while it will give you a good amount of bottom end control, it also gives you a LOT of high frequency absorption in a room that will already have plenty of that between carpet, any drapes, reflection panels, etc. You could very easily overdamp the highs. 

Now, if you wanted to do the drywall ceiling, then do soffits inside with FACED insulation, you'll get a bit more bass control and reduce the high frequency absorption. Using a more dense covering, you'll drop the frequency at which the reduction in absorption occurs. This would technically be more of a limp type of membrane rather than something that is tuned.

Bryan


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## Andre (Feb 15, 2010)

I would think that blowing in cell onto just poly stapled to the joists would cause it to sag and make it harder to put up the drywall. I would say it would be easier to use a kraft faced batt such as "NoiseReducer"


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## fredm (Aug 28, 2008)

When you get the ceiling sorted I HIGHLY suggest you get the AttiCat blown in fiberglass.

Home Depot Link


Much better than cellulose (chemically treated newspaper) and very easy to use. I did 14 bags in my parents house in about 2 hours and I was not in a hurry.


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## 22bandit (Sep 12, 2011)

My goal in doing this is to help cut down on some of the theater noise (I know its not gong to make too much of a diff especially with bass). I am only doing a single layer of drywall on the ceiling, no green glue nothing like that, simply looking for a cheap addition to help cut down a little of the sound.


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## Andre (Feb 15, 2010)

Still vote for the kraft faced high density no itch fiberglass as the easiest method....


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## dannut (Oct 20, 2011)

Okay, this is not related to acoustics, right?
Went recently through this myself. Blowing is more economical due to less labour required by skilled workforce.
Rockwool/fiberglass batts are not difficult if you have correct ceiling joist spacing, otherwise its a nightmare.

And now noticed your post regarding noise-control. Keep in mind, I'm no expert, but insulation in the ceiling is for insulation only. Apply as needed in your climate, depending on roof construction use wind-blocking top layer and stagger the seams, if using rigid board insulation. Insulation by itself is useless for noise control. Insulation for noise control is used in the air cavity between 2 decoupled high-mass layers. I would worry more about correct drywall attachment than what/how to fill the air cavity with.


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## 22bandit (Sep 12, 2011)

I was going to insulate soley to help cut some of the sound down as this is a basement and I dont think that the thermal effects will be that great. (Although I am in Wyoming so anything may help when its down deep into the negatives outside)


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## dannut (Oct 20, 2011)

Bandit, please provide a drawing or description, what rooms are above/adjacent the basement and what construction materials are used. So that noise-control engineers could give you teh optimal solution for your efforts.

Without knowing this, I would suggest mounting the ceiling gypsum boards resiliently, not rigidly and fill the cavity with loose fiberglass batts. Dont forget to caulk the seams.
A positive side effect is, that a 'vibrating' ceiling acts like a panel absorber at some frequencies, giving you some low freq. absorption, but doesn't absorb high frequencies - excactly what is needed in a small room. Hope someone could dwell on the specifics.

Also don't forget the flanking noise paths, they could render all your efforts worthless.


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## bpape (Sep 14, 2006)

Mostly correct, but, even if the 2 mass layers are connected, the cavity will still resonate if not insulated.

Bryan


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## Ted White (May 4, 2009)

Ya, as Bryan said, you don't want hollow cavities. When looking at cavities, stick with the cheapest fiberglass you can find. Your performance will not improve by spending more cash in this area. I also prefer kraft paper faced, as it's easier to work with.


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