Yet another post on "soundproofing" a workshop. But this one is multiple choice.

[FredGMeyer]

I recently had a new, detached workshop built - 15'x20', 2x6 @ 16" OC wall studs, 2x10 @ 16" OC ceililng joists, exterior walls are Hardiboard lap siding with 1/2" OSB sheathing. I have insulated the walls with R23 rock wool batts and the ceiling with R30 rock wool batts. My goal is to reduce, as much as is reasonable, sound transmission to the outside, particularly to my neighbors as the shop forms part of the property boundary. There are 2 small, double pane (and different thickness) windows in the building, and they do not face my neighbors.

My original plan was to use a 1/2" sound deadening fiberboard like Soundstop against the studs and then 5/8" drywall on top of that...in anticipation of this, my numerous receptacles, fixtures, subpanel box, heaters, door jambs, etc., are all installed to 1 1/8" clearance from the studs.

But I've read a lot recently that fiberboard is not really all that effective at reducing sound transmission, and that I'd be better off just using 2 layers of drywall. And the more I read, the more I see a bunch of conflicting opinions. Some say mass is the way to go, and that "mass is mass", so just add a 2nd layer of drywall. Others say you need "dissimilar materials" and/or "dead space" to absorb and reflect sound, and that fiberboard is the way to go. Or some other product sheet product, such as foam or rubber-based sheeting.

I have ruled out stuff like QuietRock and mass loaded vinyl for cost reasons. Also ruled out resilient steel channels because it looks like a PITA to install. I also do not want to move all the boxes and fixtures, so I'd like to keep the overall wall thickness at 1 1/8". And obviously, it's too late to do staggered studs, or "room within a room", etc.

So, I assume my choices are:

1) Original plan: 1/2" fiberboard + 5/8" drywall

2) 1/2" drywall + 5/8" drywall (and if this is the way to go, does it matter which layer is against the studs and which faces the shop?

3) 1/2" of one of those other rubber or foam-based sheets + 5/8" drywall

Any of these options jump out as hands down the best of the group?

I'm also looking at using an acoustical sealant such as Green Glue, but have heard that they require you remove all the mechanical fasteners once the glue dries...and no mechanical fasteners = code violation.

Thank you, and this caller will take his answer off the air.

[Ken Fitzgerald]

Fred,

My shop is 30'x24' with 10' ceilings with 2x6 construction. I insulated the walls with R-19 fiberglass and had R-30 fiberglass blown into the ceiling. I covered the walls with 1/2 plywood and used sheetrock on the ceiling. I wish I had used plywood there too as it has some dings on it now. The 10' garage door is insulated and so is the walkin door. The windows are thermo pane. But.....I have 5 neighbors in close proximity and they hear very little or nothing even when I am running a major tool and my 3HP Oneida SuperGorilla DC.

One neighbor's kitchen is within 40' of my shop.

[Clint Olver]

Another cheap solution is to attach foam sill gasket to your studs before sheeting them.

C

[John Lifer]

No expert here, and I haven't had to worry about this, (close neighbors, but no complaints, I work 75% of the time with the garage door open including today for about 6 hours with DC and sander running, yesterday with DC and either TS or RAS (noisy sucker) running) But back to you, from what I understand, the two dis-similar materials are the way to go. And an air gap might help also. I think I'd put up the fiberboard, run 3/4 or 1" strips and then put up sheetrock.

[Jim Neeley]

So, I assume my choices are:

1) Original plan: 1/2" fiberboard + 5/8" drywall

2) 1/2" drywall + 5/8" drywall (and if this is the way to go, does it matter which layer is against the studs and which faces the shop?

3) 1/2" of one of those other rubber or foam-based sheets + 5/8" drywall

Any of these options jump out as hands down the best of the group?

I'm also looking at using an acoustical sealant such as Green Glue, but have heard that they require you remove all the mechanical fasteners once the glue dries...and no mechanical fasteners = code violation.

Thank you, and this caller will take his answer off the air.

Fred,

I'm in the process of acquiring the materials to rework my shop as well and was considering green glue myself. My thoughts:

1) You have indicated how green glue requires you to remove the mechanical fasteners once the glue dries... which is a code violation.

2) Drywall is typically required to serve as a limited firewall.

3) What if you install drywall with fasteners, to fully meet all code requirements, then

4) add Green Glue, another layer of drywall and (temporary) fasteners to connect the two while the glue sets.

5) When the glue is dry, remove the fasteners connecting the outer layer (but leaving the original ones).

I'd sure like to know what code spec is violated by adding an additional layer of drywall, glued to a code-meeting setup. It doesn't make sense to me.

Good thread!! :-D

[Carl Beckett]

I like the two drywall layer approach. Attached by green glue. (first layer screwed)

They do make drywall screws for attaching drywall to drywall, and I have done it before. Definitely you want the glue though, drywall screwed to drywall is prone to strip out.

But basically you are forming a laminate with an absorption in between. A good concept.

My experience is similar to Ken.... The times I have worked in and insulated and drywalled area with the doors shut and windows down, the neighbors have said unless they are 10 ft from the door they never hear it.


Btw. It's the low frequency stuff that is hardest to kill. Keep all your equipment mounted so it doesn't transmit vibrations to the floor/structure.

[Art Mulder]

What about doors? How many doors and how big are they? If you built this like a standard garage, then that big garage door is potentially a bit heat loss area, as well as sound transmission... Depends on the quality of the door + door installation.

[Bill ThompsonNM]

I don't know a lot about sound proofing, but I found this publication useful. It might help you make your decision.
http://www.certainteed.com/resources/NoiseControl%20Brochure%2030-29-121.pdf

i've gone the lots of mass route including exterior foam board covered with Stucco. Hard to tell what I'm doing in my shop most of the time.

[Mark Duksta]

Fred,

A few houses back I had a detached two car garage which I attempted to soundproof. I say attempted because it's really hard to completely soundproof a room.

Before the drywall went up I lined the studs with rubber. I then put a 5/8" layer of drywall followed by a 1/2" layer, making sure the joints overlap. The joints on the bottom layer were duct taped. I added mass to the garage door, insulated it, and made sure it was sealed up tight when closed.

There seem to be a lot of variables and all of them must be addressed. You must add mass, the room must be tight, vibration paths must be eliminated.

It seems you've done your research. I know you don't want to put up the resilient channels, but if I had to do it again that's what I would do. If you have a garage door, that would be the greatest sound leaker. If it's insulated then you'll be better off but the edges must be sealed up tight to the door frame.

After all I did to soundproof my shop it only seemed to help a little bit.

Good Luck.

[FredGMeyer]

Art - the shop has one door - it's a 42" steel shell with foam insulation. Sounds beefier than it is...this will likely be the biggest area of sound transmission, but at least it faces my house and not the neighbors. I'll do what I can to seal all the gaps around it.

Thanks for all the feedback. I'm leaning toward the 2-drywall layer approach, along with a layer of Acoustiblok or something similar as a "gasket" on each of the studs/joists. 5/8" drywall arranged vertically and screwed into the studs, all joints sealed with acoustical sealant. Then 1/2" drywall arranged horizontally and Green Glued on top of the 5/8" drywall. I figure if I'm going to have one drywall layer not attached with screws, it should probably be the lighter layer. Probably go with regular tape and mud on those seams. And I'll figure out something as far as having the benches and tools on mats or some other means to absorb vibration.

Again, I appreciate all the comments. Thoughtful, civil place, this Sawmill Creek.



Fred,

A few houses back I had a detached two car garage which I attempted to soundproof. I say attempted because it's really hard to completely soundproof a room.

Before the drywall went up I lined the studs with rubber. I then put a 5/8" layer of drywall followed by a 1/2" layer, making sure the joints overlap. The joints on the bottom layer were duct taped. I added mass to the garage door, insulated it, and made sure it was sealed up tight when closed.

There seem to be a lot of variables and all of them must be addressed. You must add mass, the room must be tight, vibration paths must be eliminated.

It seems you've done your research. I know you don't want to put up the resilient channels, but if I had to do it again that's what I would do. If you have a garage door, that would be the greatest sound leaker. If it's insulated then you'll be better off but the edges must be sealed up tight to the door frame.

After all I did to soundproof my shop it only seemed to help a little bit.

Good Luck.

[Sam Layton]

Fred,

My shop is 750 sq ft. It is constructed with 2x4's, 16" on center. I have R 30 fiberglass insulation in the ceiling and the most I could get in a 2x4 wall, I can't remember the exact R value. The outside is stucco, with brick half way up. I have double pane windows, and two man doors, one being double pane glass, no garage door.

I used 1/2" sound board, fiber board, what every you want to call it, then 5/8" drywall. All of the above did an excellent job of sound proofing my shop. If I stand right outside of my shop, I can barely hear my 3 hp cyclone going. As I walk away the sound goes away. My house is about 14 ft away from my shop. My wife can never hear me in the shop, no matter what I am running. I personally think the sound board really helped. I think I purchased it at Home Depot, and it was not expensive.

I did not use green glue or anything like that. The sound board, I think really absorbs the noise. If you really wanted to do a good job, I wander if you installed 5/8" drywall, sound board, then 1/2" drywall, if it would be any better. I have a lot of windows in my shop, and I know they are the weak point. However, my shop is really quiet on the outside. In addition, it helps controlling heat and air conditioning.

For me, the cost of the sound board was well worth it.

Sam

[Jim Neeley]

Fred,

Since it sounds like your question is answered, I hope I won't offend you by extending your question.

I've shared my plan for my outside wall but I'm also planning on enclosing the DC on the inside as well rather than deal with 3 garage doors across the shop from my DC.

I'm contemplating using 2x4 construction for enclosing a 3'x6'-ish area for my clearvue cyclone and a pair of shop-vacs with the Oneida triple-cyclone kit setup yet need a 3' man door through the inside wall for dust emptying and maintenance. This makes the surface of the potentially noise-passing door between 1/4 and 1/3 of the total inside wall area.

I was originally envisioning a foam-core door but an now wondering if the door would just be a giant drum.

Cover the door w/drywall or soundboard? Build a door? Your thoughts? Ideas? Pictures, in particular, would be appreciated!! :-):-)

[Bryan Rocker]

I have considered a material called Roxul, http://www.roxul.com/home It it now available @ home depot, however I was going to get it from the local lumber yard, Carters. It claims to be a very good sound reducer and it is also flame retardant. It comes in bats and it appears to insulate at higher ratings than fiber for the same density.

[FredGMeyer]

I just showered some of it out my hair half an hour ago. I'm using Roxul R23 in my workshop walls and R30 in the ceiling.

It's a tad more expensive than fiberglass, but I actually got a really good deal on it via special order through HD. It's heavier than fiberglass, but more rigid, so I think it installs a little easier. Cuts WAY easier - no board needed to compress it when cutting; it actually cuts like a thick cake - so it will crumble some if you're not careful. Use an old steak or other serrated knife, not a utility knife. Totally fireproof, doesn't hold moisture so it resists mold and insects better. Not quite the irritant that fiberglass is, but you do want to wear long sleeves/pants, and I used a respirator. It'll get in your eyes a bit and will cause some itching on the skin. I think you're right that it is marginally a better R value per inch than fiberglass, but it's pretty close.

As far as the sound reduction aspect, I don't know. I originally bought it because I'd read rock wool was superior to fiberglass, but have since read other articles suggesting they're about the same as far as sound transmission. Also, Roxul has two different products: ComfortBatt which is meant to be traditional insulation and comes in various thicknesses depending on your studs/joists. Then there's Safe 'N Sound, which only comes in 3 1/2" thickness, and is supposed to be a sound suppressor, not a traditional thermal insulation and is aimed at interior walls with regular 2x4 studs. I bought a package of that as well as the ComfortBatt R23 and R30...and to be honest, they all look pretty similar. I think the Safe 'N Sound might be a bit denser, but not by a bunch.

Anyway, I definitely recommend it, if only for the fire and moisture issues. Keep in mind that these are unfaced batts, so you will need a vapor barrier when you're done.



I have considered a material called Roxul, http://www.roxul.com/home It it now available @ home depot, however I was going to get it from the local lumber yard, Carters. It claims to be a very good sound reducer and it is also flame retardant. It comes in bats and it appears to insulate at higher ratings than fiber for the same density.

[FredGMeyer]

Jim - I framed a 4' x 5' room inside my workshop with the idea that my DC will go in there. I just used 2x4 studs and will use Roxul Safe 'N Sound insulation in those interior walls. I have a 32" foam-core door for that room...no idea how it will handle the noise, but I figure just being in its own room that is insulated and drywalled on each side will be a lot better than having the DC in the main workshop area. All the exterior walls will have the treatment I talked about earlier, so I'm not too worried about gargantuan amounts of noise escaping to the outside. I imagine other stuff you could do would be to be meticulous about using weatherstripping around the door to your DC room, adding door sweeps on the bottom of the door, and maybe even affixing some mass loaded vinyl to the inside surface of the door...though that kind of weight on one side of the door might make it have a tendency to slam shut.


Fred,

Since it sounds like your question is answered, I hope I won't offend you by extending your question.

I've shared my plan for my outside wall but I'm also planning on enclosing the DC on the inside as well rather than deal with 3 garage doors across the shop from my DC.

I'm contemplating using 2x4 construction for enclosing a 3'x6'-ish area for my clearvue cyclone and a pair of shop-vacs with the Oneida triple-cyclone kit setup yet need a 3' man door through the inside wall for dust emptying and maintenance. This makes the surface of the potentially noise-passing door between 1/4 and 1/3 of the total inside wall area.

I was originally envisioning a foam-core door but an now wondering if the door would just be a giant drum.

Cover the door w/drywall or soundboard? Build a door? Your thoughts? Ideas? Pictures, in particular, would be appreciated!! :-):-)

[Mel Fulks]

Glad to hear of the Safe n Sound product. A while back I installed an attic fan, the install directions said to put it at least 3 inches back from the louvers. Decided to drop back all the way to the next rafter and make a very sturdy box for it. Made the fan sound like an airplane! To quiet it I used a lot of chicken wire and fiberglass insulation.Did not help much,I was surprised at how ineffective it was. After reading thick rubber would block sound I bought some 18 inch carpet tiles from the Restore. Took out the fan and lined the box (and covered the outside)with 2 or 3 layers. That worked pretty well,but what a lot of extra trouble.I am sure I won't be doing any more sound proofing by trial and error.

[Stephen Cherry]

One of the best sound things that I did was move my air compressor to the basement.

[Ole Anderson]

Personally, I think you are overthinking this issue. If you have hardiboard over OSB on 6" studs with R30 rockwool and you plan on drywalling the interior, I say you have done plenty. If you are still concerned, just add another layer of drywall in the interior to match your electrical box standout amount. Any more will give you a virtual unmesurable difference in sound attenuation to the neighbors.

With regard to soundproofing your DC system, you will need to exhaust it to the interior if noise to your neighbors is your concern. If you build a closet in your interior, just add a layer of 3 1/2" safe n-sound to the interior of the closet and add a glued layer of drywall to your door interior and watch your path of exhausting air back to your shop, make it circuitous and line it with rock wool to absorb reflected sound. That is basically what I did and here is the results in sound attenuation: http://www.youtube.com/watch?v=8X8qwMqm3Ek

To directly answer your original multiple choice question, I go with numbr 2: 1/2" rock over 5/8" rock, both screwed and then taped.

My DC door is constructed of a sandwich of 1/2" drywall between 1/2" OSB with a fairly narrow perimeter of 1/2" solid wood at the edges of the drywall. Good and heavy.

[Ruel Smith]

As someone who's in construction, typically, most sound deadening in commercial buildings is done with simply applying bats of insulation between the walls. Sometimes, they use normal insulation, but sometimes they'll use bats that are specifically engineered for acoustical sound deadening, such as this: http://insulation.owenscorning.com/homeowners/renovation/products/quietzone/

Low frequency sounds are subdued best by hard material such as concrete. Higher frequency sounds are subdued by soft materials such as foam or insulation. Hence, as a drummer, it makes the most sense to put my drums in the basement with some sound deadening to boot. The same goes for your workshop. Typically, you're sounds are higher frequency sounds coming from table saws and planers and such. Soft material such as an acoustical foam or bats of insulation should take care of that issue for you.

[Harry Hagan]

Article posted on FineHomebuilding website:
http://www.finehomebuilding.com/item/25962/soundproofing-lessons-from-a-custom-built-sound-studio

[Alan Lightstone]

When we built our home theater, the walls consisted of 2 sheets of drywall, R30 insulation, air space, insulation, then 2 sheets of drywall. I've measured 130db inside, and ambient noise levels outside it.

Overkill for a workshop? Probably, but it sure is soundproof.