How Much Soundproofing is Enough?

[baw_heed]

Hi, I've had a read through a good few posts and I know another newbie question must be a pain but if anyone has the patience to read this I’d be very appreciative.

BACKGROUND
I’m not new to recording but I am new to soundproofing. I have an ideal space in the double garage of my new house for recording – unfortunately it’s next to a road that is busy during rush hours (ok - slightly less than ideal then). There is not outrageous levels of noise (more lots of low level) but enough to hear on a recording (particularly in the wet). There is also a boiler in the garage that tends to have a bit of a click and a rumble from time to time.

ANSWER - Isolation Booth! A big project isolation booth would be ideal. I have a lot of experience of using VO booths and know the effect they have. Unfortunately I don’t have the time or money for such a construction. Also, I’d like to build a semi perm structure that could be moved once my kids decide they want the garage (it’s not glamorous and shows little commitment to recording I know - but it’s the truth).

Therefore my goals are modest – to build a modest isolation booth (prob 2m x 2m) to record acoustic instruments without the external noise disrupting. To that end I want to deaden most external sound and create a relatively decent recording environment inside. I am not looking for a completely dead room and I understand that I’d have to go to extreme lengths to do this. Therefore – this is a practical, not a perfect, solution I’m looking for.

WHAT I’D LIKE TO KNOW
However, before I embark on a massive mission I’d be grateful for advice on the following.

1) Is there anyway I can measure how much soundproofing I’ll need given the levels of noise I’m experiencing? Even if it's just "lots", "some" or "little".

2) I plan on ……………
* constructing the box/booth out of timber and Gyproc Soundbloc
* Double sheets of Gyproc Soundbloc – ie one either side of the timber frame to create a cavity in a mass - air - mass way)
* covering the outside in either Mass Load Vinyl or Sonic Cord. Poss using "Green Glue" but not convinced yet.
* Acoustic foam inside.
* I’ll seal the edges with metal tape.
* I’ll be using a large domestic Double Glazed Window that I know has good sound blocking properties. on one wall. This is big enough to be the door as well (no health and safety officer here )


So really two main points – How do I know how much I need to soundproof – and does my current plan sound viable?

Many thanks for your patience.

All the best.

 

[John Hile]

So to clarify: Are you making a free standing Iso Booth?

If so

* construct the box/booth out of 2 x 4 @ 24" OC with insulation in the cavity

* Double sheets of 5/8" Drywall – 1 layer on the inside of the timber frame and 2 layers on the outside to create a cavity in a mass - air - mass way) Skip covering the outside in either Mass Load Vinyl or Sonic Cord. This is just more mass and is costly. If you want mass, use the less expensive and better performing 5/8" drywall.

*At this point you need damping. I would highly recommend using "Green Glue" in between the panels. Many many studios have used Green Glue to damp the panels with great results.

* I would recommend sealing the edges with a pliable putty such as "Mortite", which is typically available on RV web sites of all places

* The large domestic Double Glazed Window will be the weakest link though it will add some isolation. Not so much in the lower frequencies though.

* Acoustic foam on the inside of the iso booth for in room sound control.

I hope this helped

 

[bpape]

Don't forget the floor. A lot of the low frequency rumble from the road is coming through that way. Build your own floor system that's decoupled and build the room on top of that.

If you just build a standard room but freestanding, you'll be fine. Double drywall is good along with green glue. Insulate the walls well. Pay specific attention to any electrical boxes, light switches, light fixture boxes, etc. All of those will leak if not properly enclosed.

Tape on the joints isn't going to stop bass. Caulk everything. Make sure you alternate layers when building so the seams are more z shaped rather than a straight shot in the corners.

Good luck

Bryan

 

[RICK FITZPATRICK]

Build your own floor system that's decoupled and build the room on top of that.

I've come to the personal conclusion, that wood framed floors, even when isolated are simply a membrane with very little mass. Structural vibration transmission from the floor to walls can occur which then act as membranes themselves, transmitting vibration to the
surrounding space air volume. Impact noise from drums, piano pedaling, etc will transmit right into the floor.

Actually, floating a floor/room is a lesson in hindsight when using framed wood for a floor. And most people don't need it. For very HIGH Transmission Loss goals, floating a CONCRETE FLOOR is the only real option. And then build a room on that. However, it is UNMOVABLE...hence it is permenent. And its expensive.
For non perment construction, I'd suggest floating the walls on decoupling products, and then use a roll out fiberglass or fiberglass panel product with decoupling pads built in. Use this over existing concrete floors, and lay a subfloor/finish floor on top of the fiberglass product. There are numerous manufacturers...heres one.


http://www.greenspec.co.uk/productpdf/IsoAcFloorSlab.pdf

 

[John Hile]

A floating concrete floor is pretty hardcore that's for sure.

Bryan's suggestion of freestanding floor is a great idea, and to overcome the issues that Rick mentioned I would recommend using double Plywood or OSB with Green Glue sandwiched in between (to take the resonance out of the panel) Also I would use regular pink insulation in the floating floor cavity. By doing this you can attain TL numbers that can compare to concrete.

I would think that for your project this would be fine.

John

 

[bpape]

I'll agree that in many cases, it's not needed. However, given the specific issues stated by the OP (close to a road, ie, lots of low freqency rumble, etc.) - IMO the isolation provided would be worth it in this case.

Bryan

 

[RICK FITZPATRICK]

A floating concrete floor is pretty hardcore that's for sure.

Ok, well, heres an idea for a mass filled floor.
Chalkline the outer dimensions and joistlines of the floating floor on the existing concrete floor.

Build the framing on the floor, bottom face up. Screw or nail 1"x1"(nominal)cleats at the top inside face of each framing cavity. Contact cement Sylomer(or other) decoupling pads on the framing at manufacturer recommended spacing especially at the perimeter where the walls attatch. Turn the framing over and position to the chalklines. Level with shims under the pads.

Then fill the joist cavities with one layer of drywall and caulk. Now fill the cavities with multiple layers of drywall, using Green Glue between each layer. Caulk the final layer. Now shieth the top face two layers of 3/4" MDF(more mass then OSB). , again using green glue between the final layer of drywall and the MDF. Screw the MDF to the framing. Be sure to offset the joints , I believe this will fill the bill

Couple of points to remember. Decoupling with any product, is only as good as the recommended weight to product density, and recommended "compression ratio", which actually determines the frequency at which resonance occurs..or something to that effect. Its been a while since I delved into this rehlm of studio building. And remember, its not just the floor, but the walls, cieling, equipment AND PEOPLE that needs to be figured in.

There are many products out there for this purpose, but all are based on this compression/weight ratio(?)factor to work. Not an easy challange calculating this stuff, but doable. Simply floating a floor on Neoprene or something else does NOT guarantee decoupling will occur correctly. You could waste a lot of time and money.
However, this is all assuming the local Building Inspection Department approves prior to building. See below.

Not only that, but there are other factors to consider. Like cracking the existing slab. Believe me, it happened to me!! Even with NO additional mass in the cavities. OR...the above mentioned...walls, cieling, equipment and people. This will be one freaking heavy unit.

Heres my take on doing this stuff.

In my early HR enthusiast days, when there wasn't much info on this stuff, I used what I thought was a common sense approach to building a "floating floor". In my inexperienced exuberance at my "brilliant" solution, I embarked on building "floating floor" MODULES, which I built on a seperated garage concrete floor slab. I did what I suggested above, only I was going to fill the framing with sand. Didn't even do that. I ended up using insulation, and 2 layers of 3/4" MDF. Well, there were 3, 5'x12" modules, tied together at the builtin cable chases. Each module took 4 guys to move into place. One thing that I failed to take into consideration was leveling. Once I shiethed the bottom to seal the cavities for sand, I couldn't level it once positioned. Dumb. Also, I used a cheap "neoprene foam" for the decoupling pads. DUMB. Since I couln't level the units, some of the foam pads compressed more than others due to irregularities in the slab hieght. NO slab is perfectly flat, although it may appear to be to the eye.
Another DUMB thing was building this in a RENTAL!. No sooner than I had built the floor, my landlord informed me he was selling the house. Fuck. Time to disassemble these units. Unfortunately, a storm occured a few days before I could get to it. When I finally removed the first module, I was totally blown away. Not only had these units cracked the slab, but moisture seeped up through the cracks, and formed small pools of water....geeeeezus...what a dummy! My landlord was NOT pleased.

Couple of other things. First is PERMITS. ANY TIME, you enclose HABITABLE space, the Building Inspection Department wants to know about it.
Especially when it comes to VENTING, ELECTRICAL, STRUCTURAL, EGRESS and other factors. Code infraction or lack of a permit can lead to serious consequences. Like loss of insurance should something happen.


Needless to say, you might want to investigate the various considerations this project implys before you proceed. You might want to read this before embarking on your project.
http://www.johnlsayers.com/phpBB2/viewtopic.php?t=8173
http://www.johnlsayers.com/phpBB2/viewtopic.php?t=4442
http://www.johnlsayers.com/phpBB2/viewtopic.php?t=2921&highlight=garage

One word of warning. Set aside some time for reading. The last thread is NINETY PLUS PAGES! But it DOES address all the issues I've mentioned.
fitZ

 

[twentyfootman]

shock absorbers

This is an ideal situation for floating an entire room on 4 shock absorbers. I have a friend who did this 25 years ago in an apartment with neighbors on 3 sides. He got airline shock absorbers from boeing. You could probably use truck size absorbers and end up with a floated cement floor. I'm under the opinion that green glue sucks though [ unless you have time to wait for it dry and then add more because it shrank and broke any seal tou thought it made}.I live in the northwest where moisture is an issue. A layer of water based goo has a possibillity of turning into mold. I've seen it happen. Sound-board with silicone on the edges is cheaper, easier and effective. Thanks for reading. Good luck

 

[RICK FITZPATRICK]

Sound-board with silicone on the edges is cheaper, easier and effective.

Oh really. For what? Maybe you can provide your lab test analysis of its transmission loss value.

 

[witzendoz]

I am wondering why he reactivated a thread from last year?

 

[twentyfootman]

sound-board sandwich

Is rick saying sound-board is a useless product. I've installed truck loads of board into pro studios. Almost always inbetween 2 layers of sheetrock. Is rick saying green goo is as good as a layer of sheetrock. If so it is cheaper and easier to install sheetrock. Please get back to me on this as I have upcoming projects. For the small iso room I would consider using cinder-block with tile on the inside walls. A higher stc than wood frame and a great sound for the quieter instuments.