# About to drywall workshop - do I need to fix/double check anything?



## ADHDan (Aug 17, 2012)

I'm almost done insulating my workshop to minimize sound transferrance. I'm working on a standard framed interior wall with paneling on the non-shop side (a family room) and open studs on the shop side. Eventually, I'm going to replace the family room paneling with drywall.

For soundproofing, I put two layers of pre-cut styrofoam (.5" by 14.5" by 4') in each stud cavity, separated from the drywall and from each other with a series of permiter screws. Thus, I've got five alternating layers of air pocket/styrofoam. I cut and roughed in the styrofoam as best I could to fit around electrical and cable cords and boxes. Now, I'm about to start using a spray-foam (this stuff: http://www.homedepot.com/p/GREAT-STUFF-16-oz-Gaps-and-Cracks-Insulating-Foam-Sealant-162848/100003351) to seal the edges and gaps. Once that's done, I'm putting up two layers of drywall.

I guess my question is simply, have I overlooked anything really important that needs to be addressed before I start doing quasi-irreversible work? Everything I've done until now could be easily dismantled and checked/fixed, but once I spray in the sealant it will be a lot more difficult. Is there anything I should know or check regarding the wall-cavity power and cable lines, or any structural issues I should be aware of?

Images below to show you what I'm working with. Thanks!


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## PurpLev (May 30, 2008)

curious - why double drywall? are you planning separating the 2 drywall layers from each other with an air gap?

Another thing that came to mind - if you seal gaps with spray foam, won't that in effect anchor the styrofoam to the studs and limit their vibration efficiency which could in effect transfer more sound? (to be clear - I do not know this either way, just a thought that came to mind… )

what made you plan it out this way?


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## jross827 (Apr 16, 2013)

To be honest, if it were me, i wouldn't put up drywall at all.. I would just screw on plywood or osb sheating. It gives you the ability to hang stuff wherever you want, and you could take it down somewhat easily if need be if you had to run a new 220 line or something in the future.


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## johnstoneb (Jun 14, 2012)

I think code requires double thickness fire rated with joints staggered between uninhabited and inhabited spaces.


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## MrRon (Jul 9, 2009)

Have an electrician check your wiring before closing up. If you are going to plug in machines, make sure the wiring is a minimum of #10. You can use #14 for lighting (ONLY). # 12 is better. In your last picture, I can see two BX cables near the ceiling that should have penetrated the top plate. If you can't reroute the cable, you can notch out the plate and cover with an 18 ga steel plate. An electrician will point all of this out to you


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## ADHDan (Aug 17, 2012)

PurpLev - from what I've read, two layers of drywall offers more mass and thus more sound barrier than one. Is that not accurate? Also, I don't know one way or the other whether it's better to leave the styrofoam unsealed, so if you (or anyone else) knows the science there that would be great.

This plan was suggested by a professional woodworker friend when I asked him for relatively cheap ways to (sort-of) soundproof a workshop. He suggested the alternating layers of air/styrofoam, with two layers of drywall. I thought about using resilient channels, but I need to hang cabinets and that would short-circuit the RCs.

jross - Drywall is a lot cheaper than plywood, and I believe it provides better soundproofing. Also, I plan on running French cleats along the wall for a modular approach to wall storage.


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## PurpLev (May 30, 2008)

OSB is good generally for hanging stuff on, but may not be ideal for sound barrier when compared with drywall.

on a side note - I worked on a home-theater room some years back. it was adjacent to the living room, and for sound insulation all I can remember is that they had a double drywall - and <maybe> insulation between the studs (cotton looking insulation) and with the sound (my install) at high volume nothing was transferred outside that room.

so I think you might have over done it - but better overdoing and having it work then not doing enough and being disappointed.


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## ADHDan (Aug 17, 2012)

MrRon, that's a really, really good idea, thanks. I just called my contractor, who does everything - construction, plumbing, electric. He's going to be at my place hopefully tonight or tomorrow to review my work and my plan, and let me know if I've created any danger of burning down my house.


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## Charlie5791 (Feb 21, 2012)

If you don't isolate the drywall on the shop side, from the studs, pretty much all of your Styrofoam does nothing but fill a void. The drywall on the shop side if attached directly to the studs will transfer to the panelling on the non-shop side using the studs as springs. The styrofoam doesn't do much. A better choice there would have been Roxul (mineral wool) if you're trying to keep costs down. It's a much better sound insulator, but you still need to run some hat channel on the shop-side studs to separate the shop wall from the studs. If it's too late to do anything about the styrofoam or if budget doesn't allow for it, then at LEAST run the hat channel on the shop-side. And seal EVERYTHING. Even the space around an electrical box will transfer enough sound that you may as well just leave the door open.


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## ADHDan (Aug 17, 2012)

Charlie, will bolting cabinets to the studs and/or using French cleats (also to the studs) short circuit the channels?

Edit - I am also planning on running 1/4" foam padding (like underlayment) along the stud edges, between the studs and the drywall. And I did check with multiple sources who said that the styrofoam plan would work about as well as rock wool. (Hopefully they are right!)


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## MT_Stringer (Jul 21, 2009)

I think you need more elect outlets now, not later when you will regret it. Do it. You can thank me later!


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## Charlie5791 (Feb 21, 2012)

Hat channel is just made to isolate your wall board of choice from the studs so the wall doesn't pass vibration to the structural members. So not sure what you meant by "short circuit". If you put foam padding on the studs and then compress it between drywall and stud, you've essentially removed its effectiveness almost entirely. And don't get me wrong, I'm not saying the styrofoam is useless. I've done it. It just doesn't compare to the roxul (I've done that too). Roxul is pretty dense but has an open structure. You can cut it with a bread knife. So it's not the "rock wool" that looks like fiberglass. There's also actually a paint-on membrane you can put on your first layer of drywall before putting up the second layer.

There's all kinds of tricks and some are just more expensive than others. In the end you do the best you can and hope for the best result 

Without knowing more about the how the "noisy room" is situated among the "not-so-noisy rooms" it's kinda hard to make specific suggestions. AND… it appears I've arrived a bit late to this party anyways hehehe.


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## brtech (May 26, 2010)

I did a bit of Googling, because I've never thought of styrofoam (expanded polystyrene) as a sound isolator. There are some who claim it helps a little, and others who say it hurts:
When one uses polystyrene in a cavity as partly filling you will DEGRADE the acoustic TL properties of that wall.
Since closed cell it will decrease the air cavity making that air spring stiffer thereby increasing MSM which not only influences the frequency of the resonant frequency in itself but the whole subsequent TL curve, which is related to that resonance frequency.

From that point of view your dad is right: it does exhibit some soundproofing properties: it makes that wall significantly worse (even when compared with an empty cavity).

If you make it into a glued/bonded sandwich panel, it acoustically starts behaving quite different and is not related to traditional drywall discussions here.

Rockwool is the recommended material. Mass helps, so the double thickness of drywall is a good idea. Isolating it from the studs is a really good idea.


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## ADHDan (Aug 17, 2012)

I'm actually good on electrical outlets on that wall, since that wall is pretty much going to be used for cabinets and storage. I'll put in more outlets along the opposing wall, though - that's where my benchtop/stationary tools are going. Except for the table saw, of course.


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## sixstring (Apr 4, 2012)

Coming from my experience in building music and rehearsal studios, the BEST method of isolating sound is through mass and separation. If you could build a box inside of a box (ie. two framed walls with an air gap in between) and have as much mass as possible on the walls, you can almost achieve complete isolation.

With that said, we rarely have the space to afford the box in the box method… but using double thickness material (drywall or plywood or both) helps tremendously. Personally, I think it's best to seal every possible way that air and sound can escape… This also solves the problem of dust traveling in between the spaces involved.. especially if it's a family room. Things like bass traps in the corners can really tame the thumping bass from kick drums and bass amps… likewise, it will tame the abnoxious noise from compressors and planers and while it may still be audible outside, having the low and high frequencies tamed will make it seem far less annoying and noticeable.

And you are correct in thinking that styrofoam is NOT a good method of trapping sound. It doesnt have the mass. Rockwool, if you can find it, is the material of choice because of mass per square inch (density) and it's availability/price. It's more common in Canada and colder parts of the region for the same reasons. Otherwise, Owens Corning makes a similar pink product with nearly the same density/properties. Forgot the name though… it's what I used for my bass traps in my own studio. Foam is best for controlling higher frequencies and has it's own place in acoustical treatment… but nothing to do with sound isolation. The whole egg crate on the walls idea is nothing but a fire hazard and a way to store eggs on your wall.

There's my 2 cents on acoustics.


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## ADHDan (Aug 17, 2012)

Well, it sounds like the general view is that styrofoam is not the best sound insulator, which is bad news because I'm just about done with the styrofoam insulation and I don't have the budget right now to redo things. The good news, however, is that eventually I'm going to be replacing the paneling on the other side of the wall - which will give me a second bite at the apple. I can leave the styrofoam for now and see how bad the noise bleed is, with the styrofoam. If it's livable, I can just leave the styrofoam in when I redo the paneling; if it's bad, I can swap out the styrofoam for a different product at that point. (As long as my contractor gives the ok on the current setup.)

Does that make sense?


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## Woodbum (Jan 3, 2010)

Other than adequate plugs, both 120 and 240 volt as needed, I would install 2×10 blocking between the studs where you anticipate hanging things like cabinets. Drywall is easier to fix if damaged, and the material is cheaper, but the taping, bedding, sanding and finishing labor is expensive if you have it done. If you choose to do it yourself and have no experience in this, BEWARE! You will be surprised how hard an easy looking process this is.


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## Charlie5791 (Feb 21, 2012)

Dan, Roxul is available at Lowes if you have those nearby. Roughly the cost to fill 6 stud bays (2×4 studs, 16in on center, 8 feet tall) is about $38. Budgets can be restrictive and I get that, but if it were me I'd be doing it now instead of later.


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## crank49 (Apr 7, 2010)

I think I suggested mineral wool/ rock wool/ Roxul way back when you first started asking about this. I still stand by that recommendation.

I think if you attach anything directly to the studs, you negate your fill, be it Roxul, styrofoam, mineral wood or what have you. Putting a resilient (foam rubber) layer between the studs and the sheetrock seems to me like it will make it impossible to tape and fill the joints and screw heads where there will not be cracks and such.

Plywood or OSB, which I also recommended a couple of threads ago would be better for supporting shelves etc. and could be covered with sound dampening type of sheet rock on spacers.

But, you ignored all my suggestions anyway so I don't know why I am bothering to post here this time. Just love to be ignored I guess. Good luck.


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## Holbs (Nov 4, 2012)

i would toss in a couple phone & computer outlets while walls are open.


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## davegutz (Oct 16, 2012)

My personal experience with soundproofing my wife's yoga space from my workshop, both being in the basement, is that extra layers of drywall and MDF help tremendously. There is an app you can download for free to your smartphone that will measure dB sound. When I added drywall (I now have 2 layers of 1/2" greenboard on each side - would have used firecode if not basement) the sound transmission dropped to "very tolerable level" according to the boss. I stuffed as much fiberglass insulation as I could into the empty wall space and I think it helped but cannot be sure. I was able to measure sound then add drywall and remeasure and notice a considerable difference due to drywall. Also when I added MDF to the steel exterior door I used for entry door the sound level in the room dropped most of all. The denser and thicker the material the better it worked is what I noticed. I didn't do the staggered studs or put goop between the drywall but I've heard that helps too. The main thing was to get heavy panels on the walls. There's nothing more economical than drywall and MDF. Also, I know from other experience that plugging direct air leaks helps very much. Anything that passes light passes LOTS of noise.


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## Redoak49 (Dec 15, 2012)

My recommendation is that you take pictures of the walls before the drywall. This will provide a good reference as to where the electrical wires, studs and anything else is.

I have been doing this and the few times that I needed it, it was really welcome.

Besides more electrical boxes, you should review if you want to run Coax cable or ethernet cable to outlets.


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## Charlie5791 (Feb 21, 2012)

For future reference, you can achieve a very high level of sound reduction by using a 2×6 (or 2×8 if room allows) top plate and bottom plate, then using twice the number of 2×4 but staggering them so you have 16 on center on each side, but each side is offset from the other. You can now weave your rockwool horizontally if you wish, but the point is that the drywall on one side of a wall constructed this way, is all on its own studs. The 2 sides of the wall do not share studs so the surface of one wall is completely isolated from the surface of the other. Yes it means buying twice as many studs, but studs are cheap in comparison to all the other crap you could get into buying to reduce sound. Also makes it a cinch to run wire. No holes to drill.


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## shawnmasterson (Jan 24, 2013)

every hotel I have worked in had 5/8 DW then black board then 5/8 DW on both sides of the wall. sorry for the Black board phrase but it is the nicest term I can figure out. The on site term is just not something I like to say.


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## nailbangerdave (Jun 10, 2013)

One thing to consider, what rooms are on the other side of that wall? If my kids had bedrooms on that wall I would never use Styrofoam. It burns hot, fast, and green. The fumes and smoke from that stuff is awful.

What I would have done in that situation is build a double wall with sound batts between. A single layer of 5/8 type x sheet rock hung on channel would do what you wanted to do rather cheaply. Bad part about it is losing the 5 inches or so of room along that wall. Caulk and or gasket all wall penetrations as the one guy mentioned above. Use a dab of sikaflex wherever the channel meets the stud. It's supposed to give a little extra vibration dampening. I don't really know if the sika works or not, it's just how we always built this kind of wall.

As for your cabinets, if you use 1/2 inch channel you can use 1/2 inch osb or plywood to shim the areas where the cabinets are to be screwed to the wall. The vibration transfer will be minimal if you use sika on the shim between stud and sheet rock (if that actually works). If you know exactly where your cabinet hanging screws are going to be when you shim, your shims can be as small as 1 inch by 1 inch. The smaller the better.


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## LakeLover (Feb 2, 2013)

If you are going to do the otherside, run a 2x steel stud wall to seperate it from the wall you are working on. Steel studs are cheap. Then a RC of hat channel on that side will help a lot.

Roxul is made from slag left over from refining copper.

As for attaching your cabs to the wall ? Just a thought make free standing cabs. or hang them off the ceiling.

An old engineer I used to work with would spec sheet lead for sound proofing. But I don't think that would be cost effective. One other thing he mentioned often, the walls should not be parallel , but this was for a recording studio.


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## LeeBarker (Aug 6, 2010)

Whew Lots of stuff here.

I concur with the staggered studs on a wider plate, and that could be retrofit (to solve this issue in future).

I also recall, from general contracting in days of yore, that when we put the second layer of DW on we used panel adhesive, screwed it on, and then backed the screws out when the glue had set. All part of the effort to negate the tympani effect.

Kindly,

Lee


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## MrRon (Jul 9, 2009)

The staggered stud arrangement was the first thought I had, but since the wall is already up, I didn't bother to mention it. It is still the best method to reduce noise transmission. If you have enough space, you could erect a second wall and space it about an inch from the current wall. 2×3 studs could be used.


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## Grandpa (Jan 28, 2011)

I agree with Lee….lots of stuff here. With all that has been said I have a couple of thoughts. In my church we have some very large rooms that have expanding dividers to make smaller rooms. They dividers are close to sound proof. They have lead in them. This might also add to the theory that solid or dense products are better for sound barriers. The second thing I wanted to mention is a situation my friend got involved in. He was a general contractor and some people hired him to soundproof a room. They wanted their son to be able to play his music as loud as he wanted and they wanted to contain it in his room. I am not sure why they wanted to contribute to his deafness but that is just me. Anyway, he tried all the insulation and sound board on the walls etc. He still had massive amounts of sound leaving the room. He added more insulation etc. No good. He final changed the hollow core door to a solid core door and he had it. Same jamb and everything. Just the slab door changed. Sealed the sound in the room. Might add to the theory that dense things stop some of the sound.


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## ADHDan (Aug 17, 2012)

There was a lot of incredibly helpful advice in this thread, and I appreciate all the responses. I was on board to admit my mistakes and switch to Roxul, but after talking with my contractor and discussing expanding family needs with my wife it looks like I have to give up the lower-level workshop and instead convert part of the garage into a shop.

On the plus side, this will give me a significantly bigger shop (roughly 24×12 instead of 17×12), I've got the go-ahead to start this project immediately, and we'll be able to get another bedroom in the house and expand our downstairs family room (and I won't have to worry about noise as much). On the minus side, it means I'll have to park my car outside in Minnesota, albeit in a three-side enclosed carpark. I'm not 100% thrilled with this, but it looks like the best compromise considering my family needs.

Thanks again for all of the responses. I learned a lot, and fortunately I didn't sink more than $100 into the project before discovering that it needed to be rethought. And now I get to learn a new skill: buillding interior partition walls.


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## Knothead62 (Apr 17, 2010)

I portioned off a part of my basement/garage to contain the sawdust. I used the cheapest OSB that I could get. One of these days, I'm going to a pawn shop that has odd & ends of paint and paint it. Sheetrock will dent, etc. and you will have a hard time hanging stuff on it.


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## LakeLover (Feb 2, 2013)

Think you made the best choice there. So much easier to move machines and materials around.

I never park my car/truck in a garage, but I never drive anything that new.

When we built I did plan on a car port, now that we have lived here for a while and have put off finishing the covered porch. I have been thinking of integrating both.


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## Charlie5791 (Feb 21, 2012)

I park outside and I'm near Buffalo, NY so you get the picture. I got a remote start for my van. I still have to brush off snow, but the remote start means I don't have to scrape windows 

And actually… I'm ok with this. I would LIKE to have a garage space, but we're using that bay for other stuff and I'm really ok with it.


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## ADHDan (Aug 17, 2012)

That's good to know. Minnesota winters are terrible, but hopefully with an enclosed lean-to over the car park I can manage. And I will like having the bigger space, and being able to open the garage door for extra space and fresh air when it's nice out. Also, less noise worry, etc.


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## KentInOttawa (Jun 25, 2013)

Another option that will help is to borrow a trick from the light steel framers. They will mount a channel horizontally across the studs; think strapping. This channel is only screwed down on one side, allowing it to flex in and out. The drywall is then screwed to the channel. The result is that the sound energy effectively has to push past a sheet of drywall attached to a spring. This is also much thinner than building additional layers of wood framing or strapping.


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## ADHDan (Aug 17, 2012)

Well, the garage idea didn't pan out due to major cost, timing, layout, and other issues. But I think we have a final resolution: ditch the Styrofoam, switch to Roxul, pad the studs, and put up two layers of drywall. I've got coax jacks and power outlets installed (contractor-approved), and I'm taking pictures before I work and putting in metal stud plates as necessary.

Of course, there's always more I *could* do (and a lot of great suggestions in this thread for what that would entail), but between my need to hang cabinets and lumber racks and my time constraints (I have a toddler and a demanding day job) I think this will be good enough for my "weekend warrior" needs.

Thanks again to everyone for the advice. I really do appreciate it.


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## ADHDan (Aug 17, 2012)

Just wanted to follow up, this is now complete. I installed Roxul with two layers of drywall, hung my cabinets, and am working on unpacking my tools (we just moved). I'll post an album once I've got a setup finalized. Thank you again for all your advice.


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