Soundproofing attached garage - Page 3

Soundproofing attached garage · 10-01-2009, 11:35 AM

I want to make an attached garage into a workshop. However,
soundproofing is an issue that doesn't seem to have a
satisfactory answer at reasonable cost. Does anyone have
experience in this area?

scsmith42 · 10-05-2009, 03:36 PM

Originally Posted by max_in_graham

Thanx for the kudo's... but I'm really just a long winded ol' cuss....

The whole principle of mass being your friend is what you are after. The more effectively that you can create a solid mass is what you are trying to achieve... and hopefully within a reasonable budget. (oof... that's the one is what kills ya!)

As far as open cell spray foams... There's a bit of debate on it.

Many of the "acoustic foams" that actually work, are open cell foam. Technically they do work... but the amount of low frequency absorption is actually so little that it doesn't work in terms of practical numbers. Closed cell foams are worthless.

Again, this is in reference to open cell foam use as an acoustic treatment, and does not have a thing to do in terms of the spray foams used in the construction trades.

The little data I have seen in regards to the spray foams is that the closed cell seems to resemble it's cousin, bedding foam. e.g. decent thermal properties but less significant at reducing LF transmissions than a piece of paper.

The spray open cell foam's are fairly new technology that haven't yet been sent to places like Riverbank for testing. (If they have, no one has been discussing them.) However, IMVHO, I would guess that the open cell foams are going to work fairly well at both thermal and sound absorption... probably far better than they do as a standard acoustic treatment.

The fact that they are creating more air cells in a tighter confined space, e.g. stud bay, that they are actually creating a much more compressed "spring" and thus, would absorb more sound energy.

I remember you taking me through the farmhouse, and yes, it was darn quiet up there! So, I wouldn't be afraid to try it at all.

I would consider using 1/2"-ish plywood or even 3/4" chip board (non cert OSB) and green glue with one layer of 5/8" gypsum for your gennie room with regular pink fluffy... IF you decide to not use the open cell spray. Again, the rigidity is a compounding factor to the mass equation. The more you can tie the whole structure into a single mass, the better.

It's not like you couldn't go back and add more gypsum, but I'd probably try the open cell spray and a single layer of either wooden sheet good or gypsum and see what you get.

You could also try getting your compressor isolated by floating it on a suspension pad. (Floating a single tool is a LOT easier than an entire room.)

Max, that's good feedback - thx. I already have the generator skid sitting on rubber mats and 2 x 4's above the slab, so hopefull that will help isolate the vibration. The engine fan also pulls air out of the room and forces it outside through the radiator, and I think that this may help pull some of the sound outside.

My biggest concern is the door to the room. I have a double door (interior), and I doubt that it will do much in terms of noise deadening. I was thinking about installing a liftable baffle on the generator room side of the door (probably on a counterweighted pulley system suspended from the ceiling for easy removal). After reading your comments on the "gobo's", I may opt to copy something like that for baffle.

max_in_graham · 10-05-2009, 06:14 PM

Scott,

You'd actually be surprised at just how much deadening you can probably get from your doors, just by installing air tight weather stripping around them. Foam weather stripping is probably adequate, but a good soft neoprene will out last the foam stuff by years.

Even tacking some narrow 1x to the existing door stops to make a second seal will make an improvement.

If the doors are hollow core, to can apply some contact cement to a sheet of 3/4" BC, OSB or MDF and attach it to the door along the edges. I'd recommend a decent sheet rock screw. Just make this plate 3/4" shorter at the top and on the sides. Then you can step back the 2nd door stop by a bit over 3/4" to accommodate your neoprene seal.

Make sense, or am I just being mildly incoherent?

scsmith42 · 10-05-2009, 08:49 PM

Originally Posted by max_in_graham

Scott,

You'd actually be surprised at just how much deadening you can probably get from your doors, just by installing air tight weather stripping around them. Foam weather stripping is probably adequate, but a good soft neoprene will out last the foam stuff by years.

Even tacking some narrow 1x to the existing door stops to make a second seal will make an improvement.

If the doors are hollow core, to can apply some contact cement to a sheet of 3/4" BC, OSB or MDF and attach it to the door along the edges. I'd recommend a decent sheet rock screw. Just make this plate 3/4" shorter at the top and on the sides. Then you can step back the 2nd door stop by a bit over 3/4" to accommodate your neoprene seal.

Make sense, or am I just being mildly incoherent?

Max, that makes sense - thanks. I actually have some 4 x 8 sheets of a special sound deadening material, so I may screw it on the back of the doors and then attach some sheetrock to the inside of it for two layers (as well as fireproofing - not a bad idea for a generator room...)

Bas · 10-06-2009, 12:26 AM

Originally Posted by scsmith42

Max, your post is the single most informative essay on sound control that I have ever read. Thanks MUCH for sharing your extraordinary knowledge on this topic.

Let me echo Scott's comments. This has been incredibly helpful, especially with all the practical advice on caulking, gaps, variations etc. The info I've come across so far generally assumes you're starting from scratch (as opposed to modifying an existing structure built the conventional way) and/ or suggests material that's hard to obtain or expensive. Drywall, OSB, blankets, weatherstripping and fiberglass insulation are items I can work with! I'm not shooting for total silence, just bringing down a 90dB machine to around 70dB. I think I can do that now.

max_in_graham · 10-06-2009, 09:38 AM

Bas,

The thing that amazes me is that the world is getting so specialized in so many "industries" that its almost like we're loosing out on good ol' common sense when it comes to products. I've seen regular speaker wires sell for $100/ft because it was claimed to have some kind of specially reduced oxygen content and "certification"... regular power cords that cost $300/each... all kinds of silliness. Most of it snake oil, too.

We have all this information we're able to gather, collect and organize, but then it gets tough to put it all together....
(Believe me, I know from first hand experience!)

The basic principle's of mass and decoupling are so obvious, that they become obscured in the midst of all the specialized products out there.

e.g. Resilient Channel and isolation clips being the biggest exception. The thing that most "acoustic professsional's" fail to realize is that they are supposed to be used under specific circumstances; metal studs and joists.

They can be used with wood studs and still be effective, but not nearly as effective as the more cost effective approach as adding a layer of sheet goods.

I've uploaded a couple of the pdf's from my set of prints about the doors...
http://www.dmmobile.com/blog/wp-cont...009/10/a-8.pdf
http://www.dmmobile.com/blog/wp-cont...09/10/a-84.pdf

This next pdf explains the "stepped" corners...
http://www.dmmobile.com/blog/wp-cont...09/10/a-92.pdf

Glennbear · 10-06-2009, 10:57 AM

Tons of good information here and lots of varied approaches. In my own experience building a closet for noise control from my compressor and DC I found out the hard way one has to follow a rule that Max pointed out:

First, where air goes, so goes sound.

When my closet was finished I had a gap of less than 1/8" at the top of one wall that to my surprise allowed a lot of sound to escape. An application of 3/4" thick molding eliminated the problem.