Need Advice-Sound Isolation For Jam Room

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Topcat53

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I know there are several threads on this topic, but it seems like the issues are different for each. I'm taking up part of my garage to build a jam space - a place to be able to turn my amps up to reasonable levels without disturbing the rest of the house and maybe do some recording. The room acoustics can come later - right now I'm wanting to make sure I get the room properly isolated. It will be about 10 x 12 with the long wall against the MBR and one short wall against the kitchen. Floor will be raised about 20" above the existing slab (house is raised foundation & garage is SOG). This will match the existing floor level of the house and without going into a lot of detail, will make the overall construction easier. The walls of the existing house inside the garage are sheetrocked with blown cellulose insulation. Here's what I'm thinking -
2 walls against existing house - studs about 1" short of touching existing sheetrock, blown cell ins, mass loaded vinyl on jam room side, then sound iso clips and sheet rock.
2 walls out into garage - basically the same except that outside will be sheetrocked
Ceiling - mass loaded vinyl on existing sheet rock, furring strips, isolation clips, new sheet rock
Floor - joists will sit on cinder blocks to raise to match existing house floor level and will insulate in between. Want hardwood flooring in the room. Beyond that I'm a little confused about how to isolate.
Door - Will go out into garage & right now I'm just planning for a good quality exterior door maybe modified with some extra sealing.
HVAC - BIG question here. Will share existing central house system (garage already does this). So how do I keep sound from travelling through ducts? Are there caps you can put on while using the room and take off when not?

Thanks in advance for any advice.
 
So far, there is alot I see wrong with your approach. Everything you've listed seems logical, but won't work in reality though. Check out studio designer John L Sayers' site for detailed info on construction. There is a shit ton to read and understand before getting into the job.

To hit on the last "big" question though.. yes, this will have a crippling impact on your isolation. To share the hvac with the house, you'll need venting in, and out of the room. This will carry sound easliy through the house. THere are many vent construction ideas on this site and others but you'll need to creat a new ventcap that has many bends and sound absorbing lining.

Good luck, and welcome to HR.COM!!
 
Thanks for the reply and the welcome. I'll check out the site you recommended. I figured the vents were going to be an issue.
 
Don't have the link now, but a company makes portable AC units that may work for you. You won't need a monster unit anyway.
 
With the walls right against the other ones, you'll have more transmission than you want. Widen the gap between your wall and the old one (and consider removing the existing drywall on the house wall to avoid a triple leaf situation). This will lower the resonant frequency of the structure.

Double the drywall on the inner wall of the new space to further lower the resonance that's transmitted. Make sure the entire space between the 2 walls is full of insulation.

Bryan
 
With the walls right against the other ones, you'll have more transmission than you want. Widen the gap between your wall and the old one (and consider removing the existing drywall on the house wall to avoid a triple leaf situation). This will lower the resonant frequency of the structure.

Double the drywall on the inner wall of the new space to further lower the resonance that's transmitted. Make sure the entire space between the 2 walls is full of insulation.

Bryan

I could easily leave 6 inches between the back of the new studs and the existing walls. Actually in looking at it, this would make construction easier and would isolate the room totally from floor to ceiling. This would give a total space of 13 inches between the inside wall of the existing structure and the inside wall of the jam room which I would fill with insulation. Would that be enough? I could also cap the room short of the existing ceiling and still have a 9 or 10 ft ceiling in the jam room. Should I plan on doing that? Does the double dry wall take the place of the mass loaded vinyl and isolation clips or do I need to install those as well? I'm familiar with using acoustic caulk to fill all the cracks, etc, but I've seen a couple of articles that recommend using it between the layers of sheet rock. What are your thoughts on that?
Thanks very much for your help.
 
More gap is better. Fill with insulation.

Double drywall is a piece of the puzzle. Using Green Glue between layers is far preferable to MLV or caulk between layers.

If the walls are decoupled from the other structure, then you can avoid the cost of the clips on the walls.

Shortening the ceiling slightly to avoid coupling to the rest of the structure will also provide increased isolation and avoid the necessity of clips on the ceiling - still do double drywall and Green Glue.

Plan properly for HVAC and electrical to avoid holes and direct sound transmission.

Bryan
 
Once again, thanks for your help - this definitely gives me a clear direction. I said "acoustic caulk" but I meant "Green Glue" - couldn't remeber the name of it when I posted. One more question, if you don't mind - this has to do with the floor. The garage floor is slab on grade while the remainder of the house sits on a raised cinder block foundation about 2 ft above grade level. The builder installed brick veneer around the base of the garage which matches the height of the raised foundation. It is installed as you would normally, i.e. there is about an inch of space between the brick and the cinder block. the slab touches the brick but not the cinder block and the area under the raised part of the house is dirt. Based on the info you've given me for the wall construction I would be looking at framing a foundation on top of the existing slab that would be inside the brick veneer and then insulating under the room floor. Do I need to do anything to isolate the joists from the slab? Also I'm planning a hardwood floor so if you could recommend what I should do for underlayment, I would appreciate it. BTW, I"m planning to run strips for electrics to keep penetrations to a minimum.
 
Using something like U-Boats will give you good isolation and they're not all that expensive. Make sure you fill the cavities underneath with insulation or you'll have resonance issues.

For underlayment, I'd do 3/4" tongue in groove plywood. 2 layers is better if money allows.

Bryan
 
Using something like U-Boats will give you good isolation and they're not all that expensive. Make sure you fill the cavities underneath with insulation or you'll have resonance issues.

For underlayment, I'd do 3/4" tongue in groove plywood. 2 layers is better if money allows.

Bryan

Bryan -

I can't believe you bought into that hype -

Define "good isolation" and then try to put it into perspective with a product that has never been tested to determine performance.........

If a company won't test products (and release the results of those tests) - we (as design professionals) shouldn't be recommending the use of those products......... we have plenty of bonafide companies out there who produce products that we CAN define a fairly exacting performance curve with - ands those are the products we should be sending people to.

They are the companies who will continue to produce newer products - testing and verifying their actual values in the field - so we can continue to design better projects as the years unfold.

I say this because there is no way for us to quantify the value (if any) of the investment
made in a product like U-boats - perhaps they work - perhaps they don't - perhaps only a little - perhaps in reverse.

You don't know which of the above is true because you have never paid to have identical assemblies built with and without them - so as to be able to compare the actual value they may (or may not) impart.

Hey - don't get me wrong - I love Auralex - think they're a great company in a lot of respects - but believe they blew it on this one - and let Steve know that way back when he was still onboard with them - nothing has changed since then.

Funny how they test eveything else - and will let you see reports on those product - but not this one...... hhhmmmmmm.........

Sincerely,

Rod
 
Bryan -

I can't believe you bought into that hype -

Define "good isolation" and then try to put it into perspective with a product that has never been tested to determine performance.........

If a company won't test products (and release the results of those tests) - we (as design professionals) shouldn't be recommending the use of those products......... we have plenty of bonafide companies out there who produce products that we CAN define a fairly exacting performance curve with - ands those are the products we should be sending people to.

They are the companies who will continue to produce newer products - testing and verifying their actual values in the field - so we can continue to design better projects as the years unfold.

I say this because there is no way for us to quantify the value (if any) of the investment
made in a product like U-boats - perhaps they work - perhaps they don't - perhaps only a little - perhaps in reverse.

You don't know which of the above is true because you have never paid to have identical assemblies built with and without them - so as to be able to compare the actual value they may (or may not) impart.

Hey - don't get me wrong - I love Auralex - think they're a great company in a lot of respects - but believe they blew it on this one - and let Steve know that way back when he was still onboard with them - nothing has changed since then.

Funny how they test eveything else - and will let you see reports on those product - but not this one...... hhhmmmmmm.........

Sincerely,

Rod

Thanks for the input - so do you have a suggestion as to another product or method I need to look at to isolate the floor?
 
Hi Rod.

Understand your frustration with Auralex. I recommend them because I've used them and find them to be effective. Obviously there are much better solutions out there if we can avoid the beam all together. Doesn't sound like we can. In that case, we do the best we can.

I'd be very interested if you have a recommendation for a similar product for this type of specific application that you feel is better and has the testing done on it.

Bryan
 
I'm now ready to begin construction. This will be essentially a free floating room inside the garage but will butt up against 1 & 1/2 existing walls of the house. Isolation from the rest of the house is a much bigger concern than room acoustics. Due to wife's elderly parents living with us, I no longer have any empty house time. Just want a place I can go and play my electrics at reasonable volume without disturbing the rest of the house. I attached a dwg & right now I'm figuring mat'ls at about $2K. Want to make sure I'm not overdoing or skimping. A few specific questions: 1. On the interior double sheetrock - do I need to Greenglue the first layer to the studs or just put it between the 2 layers. 2. Same question for floor underlayment. 3. On the new exterior walls, do I need to Greenglue between the sheetrock and the studs. 4. Right now I'm planning to build the door myself - same thickness as wall w/ tapered jamb like on a soundproof booth - good approach? 5. I know I'm going to need to figure out some baffling around the HVAC unit - suggestions on this would be welcome.

Thanks!
 

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No need to do GG between the first layer and the studs nor the first floor and the joists.

On the OUTER wall, you do not want drywall on the side that's going to face the back side of the inner wall. Take it down to the studs and fill the whole cavity with insulation. If you have drywall on the inside of the outer wall, you're creating a triple leaf that can actually make transmission worse. Plus, the wider cavity will drop the resonant frequency of the gap (a good thing).

Double drywall the inner room and use Green Glue between the layers. If you had planned on the expense of extra drywall and green glue for the outer wall, the money would be better spent to add a 3rd layer of drywall to the inside of the room. Same money spent - much better performance at the cost of 1" of interior space.

Bryan
 
No need to do GG between the first layer and the studs nor the first floor and the joists.

On the OUTER wall, you do not want drywall on the side that's going to face the back side of the inner wall. Take it down to the studs and fill the whole cavity with insulation. If you have drywall on the inside of the outer wall, you're creating a triple leaf that can actually make transmission worse. Plus, the wider cavity will drop the resonant frequency of the gap (a good thing).

Double drywall the inner room and use Green Glue between the layers. If you had planned on the expense of extra drywall and green glue for the outer wall, the money would be better spent to add a 3rd layer of drywall to the inside of the room. Same money spent - much better performance at the cost of 1" of interior space.

Bryan

Yes, I had planned to take the sheet rock off the existing exterior house walls. There will be no sheet rock between the existing interior house wall and the new interior wall of the music room - just a wide cavity filled with insulation.

Right now, I had planned on only 1 layer of sheet rock on the exterior walls, but thanks for the tip about putting another layer on the inside - something I can do later if I don't get the isolation I want.

Question about insulation: I much prefer blown cellulose insulation over fiberglass for both it's thermal insulating and sound isolating properties. I've seen it installed, but never done it myself and I'm thinking it's going to be a pain between renting the blowing machine and learning how to properly wet it down for the wall applications, so I'm just wondering - how much would I lose if I went with fiberglass?
 
If you use fiberglass in a packed state, you can get it to be just as good. The blown in will be good too though - it's really not that bad.

Bryan
 
Can I just confirm-- Is the 'drywall' you Americans speak of equivalent to our plasterboard over here in the UK?
 
Not sure on the plasterboard. Gyprock is pretty much the same thing I believe.

Bryan
 
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