Ready to build drum/music room- feedback requested!

[PaulieSkiDrum]

First of all thank you for such an informative site. I've spent countless hours on the web sifting thru sites including SAE, soundproofing, E coustics, acoustics 101, etc before finding yours, and this site really helps to put it all together.

Background first.. We live in Duvall, Washington, which is a suburb of the Seattle area. I am a drummer, and my 14 yo son is a drummer. Can anyone say "SOUNDPROOF"?? Yes, he also plays double pedal so what we are looking for is MAXIMUM isolation. Sound levels peak at 110db +-, and we are tired of playing during daylite hours only to appease our bitchy neighbor. Currently with our best efforts to quiet our 2nd flr drumroom, decibel levels peak at 65db outside the wall facing neighbor, which really isn't bad. Unfortunately the lady next door is a very unhappy person, and is always looking for things to gripe about. I should add that my wife would also appreciate some quiet. I guess she's really the one I should be caring about anyway huh? We want to be able to play anytime of day or nite, including band practice.

Our 2 year old home is on a site that slopes down to the rear, and CHECK THIS OUT- BRAG- we have 13' of head room in the rear crawlspace from the sill plates to the bottom of the main floor flr joists. From reading posts we are very lucky indeedy...

Attached is a simple drawing of the plan.

Our goal is sound isolation of 60+STC on all sides and above. As far as acoustical issues go we are planning on treatments such as bass traps, Auralex, etc after completing construction.

Here goes...

First, we currently have 2x6 exterior walls w/ Hardi-Plank over sheathing on a 6" concrete foundation all they way around, except for the 40' wall which will be a 4' high 6" concrete retaining wall. There will be a solid core entry door (opening out) to a lobby area which will have slab floor and R-21 insulation and one layer of 5/8 sheetrock on 3 sides. There will be another solid core door( opens in) to drum/practice room, and a standard door to storage room.

The floor will be min 4" concrete slab on grade for entire basement. All exterior walls will be insulated w/ R-21. The walls for the storage room will be 5/8" sheetrock screwed to exterior studs, plus whatever framework is to be constructed on the 16' long retaining wall side, as well as R-21 installed on retaining wall side. Ceiling will be standard one layer 5/8" sheetrock to ceiling joists which be be dropped well below the current floor joist( approx 1.5-2 feet). The wall facing the drum room will be a 2X4 stud wall on the slab with one layer of sheetrock and 3" of Roxul against sheetrock.

The drum/practice room is to be floated on the slab with a 2" air gap from all perimeter walls. The floor will be constructed by floating 2x4s on 1/2" neoprene squares, with 3" of Roxul between boards, and 2 layers of 5/8" OSB at 90 degree angles screwed on top. I'm not sure at this point whether we should have TIG wood flooring on top or padding and commercial grade carpet. Any feedback would be appreciated. The walls will be 2x4" studs on all sides on the floating floor w/ 3" Roxul against 2 or 3 layers of sheetrock. My plan initally was 5/8" sheetrock- 1/2" Celotex- 1/2" sheetrock following the idea of different densities many "sound people" promote, but I'm not so sure the Celotex is necessary or if 2 layers of 5/8" or onel layer 5/8 and one 1/2" is best. Help.. The ceiling will be(guess) 10'+ high, and supported by the walls, and will be, as in the other room, sitting 1.5-2' below the floor above (which is currently insulated BTW). The ceiling will follow same rules as walls with 3" Roxul and 2 or 3 layers of sheetrock.

All electrical will be run thru wall mounted conduit w/ wall mounted electrical boxes around perimeter of room in music room. Light fixures will be track lighting ceiling mounted. A/C to be mini-duct system, likely heat pump combo mounted on 14' wall facing backyard.

Questions:

1. Does it make any difference whether we put a 1/2" expansion joint between the 2 rooms so they are decoupled or is this going overboard?

2. Do we need a gap between current foundation and slab? To me it doesn't seem nec. since we are floating the floor on top of it.

3. If one leaf is the exterior 2x6 wall ( sheathing, siding, and R-21) and 2nd leaf on separate( 2" gap) floated 2x4 stud wall w/ Roxul and say 2 layers of sheetrock 5/8 and 1/2, will that be enough for maximum isolation to exterior sides of music room? I will do 3 layers of 5/8" if that's
needed. The idea of cutting and placing sheetrock against backside of sheathing for outer leaf seems very time consuming and a pain in the ass..

4. Obviously, my main concern is sound transmission to exterior walls. Am I missing anything??? Thanks for all your feedback.

I do have current crawl pics, but not sure how to add to this post..

paul

[PaulieSkiDrum]

Sorry about the size. I did read the rules first, but obviously goofed somewhere. Help!! I 'll fix it..

[knightfly]

Is the drum room the only room you want isolated from the rest of the house, or might you later decide to use the other room as a control room for recording?

Regardless, there is a very simple (but continually over-thought) rule of isolation that always applies - the infamous mass-air-mass one. In the case of your hardi-plank/sheathing wall, if you don't want to increase the mass the hard way then your OTHER leaf needs to be heavier, and further away (wider air gap) to compensate. This can have the added benefit of lowering the m-a-m resonance anyway, which would improve the low frequency isolation (good for kick drums, double-good for double-kicks )

Couple of examples, using VERY rough numbers -

existing hardi plank (assuming 1/2" here) plus 5/8" OSB for outer leaf - separate inner frame, insulated, 2 5/8" gypsum layers - 8" space between inside of outer leaf and outside of inner leaf - STC 71, but low frequency TL is around 44 dB - m-a-m resonance would fall at about 37 hZ. Drums would start being audible outside when inside SPL is around 90 dB, possibly 95 on sound level meter.

Same outer, same inner, with 12" air space - exact same STC, but low frequency improves to 47 dB, m-a-m resonance drops to 30 hZ - between 95-100 dB inside before audibility outside.

Add a third layer of 5/8" gypsum on inner leaf only, still 12" air space - STC 75, TL 50 dB @ 50 hZ, m-a-m resonance drops again to 27 hZ, inside SPL around 105 dB when barely audible outside.

Adding just one layer of 5/8" inserts between the outside studs would get you another 3 dB STC and another 3 dB on the low end.

Ceilings, to keep up with the last example, would need to be pretty beefy too - one thing that will help is the wide air gap. IF your upper floor is about the same mass as your outer walls, then supporting your inner ceiling on inner walls (insulated, of course) with a 24" air gap -

With separate framing and 24" air gap, figuring 3/4 OSB and 5/8" particle board upper floor (not mentioned, this is a guess) 2 layers of 5/8 rock 24" air space comes out to about STC 61, 41 dB @ 50 hZ, m-a-m resonance of 24 hZ (the wide air gap helps that part) -

Adding a third layer of 5/8 rock, STC 63 with TL of 44 dB @ 50 hZ, m-a-m resonance of 22 hZ. Somewhere between 95-100 dB inside will just become audible upstairs, provided there's no flanking paths (hard to do)

Your floor is where things need to change, or most of the above is pointless.

You propose a wood floor floated on neoprene and 2x4's - this would be the equivalent of a wall with only 4" air gap, resilient channel, and only 2 layers of 1/2" gypsum each side. This runs you smack dab into the "weakest link" law...

Not to mention that quite a bit of the noise that escapes thru the "crappy horizontal wall" will get into your slab, find its way up the walls, and re-radiate into the house in all the LEAST desirable spots...

If I'm correct in my understanding that you've not yet poured the floor for this part, hoooo-rayyyy...

Because the simplest, best way to avoid ALL this, probably save a few $$, and walk away with the "My Neighbor Must Have Gone Deaf Because She's Not Bitching Anymore" award (not to mention the multitude of "attaboys" from your wife which will allow you at least one "aw shit", is to pour an isolated slab in the first place.

This can be done just as a standard monolithic slab, except that NO CONTACT is allowed with the existing foundation; instead, you would dig footings separated by a couple inches from the outer footings (keep in mind that the outer footings will protrude INSIDE the inner edge of existing foundation walls by at least 4" - you'll need to dig down enough to locate this inner edge of existing footing so you can miss it by 2", and pour a standard monolith floor.

You will want a LOT of compacted gravel under the slab to keep moisture to a minimum, and check out the Building Sciences links in the REFERENCE section for the PDF titled "before you buy, build or renovate", yada yada - pay special attention to their sketches on drainage systems to make sure you're not at risk for moisture.

I'm including a basic sketch of basement walls/monolith for purposes of discussion -

Not sure how I missed this, just went thru the entire site (except for Design) this morning; hope this helps... Steve

[PaulieSkiDrum]

Steve Thanks for the excellent feedback!

I think the 3 layers and 12" space is the way to go.

1. If I'm calculating correctly, the 4" gap provided by laying the slab as you described together w/ 3.5" of 2x4 inner frame and 5.5" of outerframe makes for a 13'' gap, at least on the 2 exterior sides anyway

2. Are you saying that I don't even have to mess w/ floating a floor at all if I have an isolated slab laid as described? That would be SWEET . Then laying an expansion joint between rooms is unnecessary, or would this be beneficial?

3. The architect said today that a rigid insulation board would have to laid around the perimeter between the foundation and floating slab. Does that sound right? How thick and what type of board is this? Won't this transmit sound?

4. Provided I don't need to float my floor as described, should the inner walls still be sitting on some sort of neoprene for vibration minimizing?

5. What is that little brace in the picture between the rooms, and how does that work, how many, etc?

Thanks, I'm getting really pumped, architect will be starting drawings next week.

More questions later.....

[knightfly]

Started to answer this this morning, damn browser locked up and bailed on me; here goes again -

1. If I'm calculating correctly, the 4" gap provided by laying the slab as you described together w/ 3.5" of 2x4 inner frame and 5.5" of outerframe makes for a 13'' gap, at least on the 2 exterior sides anyway

More is always better, 13" is pretty good.

2. Are you saying that I don't even have to mess w/ floating a floor at all if I have an isolated slab laid as described? That would be SWEET . Then laying an expansion joint between rooms is unnecessary, or would this be beneficial?

Yes. As to expansion joints, depends on what you use in the joint and what your intention is for the other room (you haven't answered me on that yet)

3. The architect said today that a rigid insulation board would have to laid around the perimeter between the foundation and floating slab. Does that sound right? How thick and what type of board is this? Won't this transmit sound?

He's right; typically use EPS foam board. If you have to, 1" will work. I said 2" just to ensure that there is NO BLOB of concrete allowed to fall between slab and outer footing to cause hard contact between the two. Speed of sound is different in concrete vs. foam, and the sound would be making TWO changes in speed; one going from inner slab to EPS, and a second change going from EPS to footing concrete; these will attenuate the sound quite a bit.

4. Provided I don't need to float my floor as described, should the inner walls still be sitting on some sort of neoprene for vibration minimizing?

Not necessary; you will want something under your framing for a Thermal Break however; there is a product called "sill seal" that will work for this, but don't worry about seals between rooms - this will be covered by caulking of individual layers of wallboard.

5. What is that little brace in the picture between the rooms, and how does that work, how many, etc?

That's an isolated sway brace - used every few feet between free-standing walls to support them without flanking. There are also types for masonry.

http://www.silentsource.com/rsic_prods.html#RSICCWBxx

http://www.kineticsnoise.com/arch/index.html (check under wall section)

http://209.200.80.33/html/dnsb_brace.htm (check bottom of page for info on spacing)

HTH... Steve

[PaulieSkiDrum]

Steve

Re: the adjacent room- it will be storage/ ski tuning room w/ 1/2 bath. Not to be floating, walls all attached to current and added foundation walls.

1. If we don't separate the two slabs won't sound travel thru drum room floor to exterior walls and ceiling in the storage room.

2. Would we then split the slab by a 2'' space or something like that?

3. I went crosseyed last nite loking for everything i could find in the forum re: slab floors. Many good comments were yours, and I'm a bit confused as far as weakest link theory ( obviously my damaged brain) If my walls and ceiling are STC of 65+, does my floor still become the weakest link if i do this monolithic floating slab?

4. How much sound will travel thru grade/ground to outside walls, etc
if we properly compact and prepare grade before slab goes in?

5. Should slab be more than 4" deep?

Thanks...

Brain Overloaded Drummer

[sharward]

Let's clear one thing up. There are floated slabs and there are isolated slabs. From the looks of things, you will not be floating. You'll be isolating. You'll go nuts (and others will go nuts trying to help) if you use those terms interchangably.

In my project, I'll be cutting, jackhammering, and removing my 4" concrete floor in my garage and replacing it with a 6" isolated slab with rebar. I'd recommend the same in your case. You need strength in order to support the weight of your walls and ceiling. Slab failure will cause your studio to be ruined, so don't skimp on the concrete.

I battled the "to float or not to float" conundrum myself for months. Here is the point where I proposed to do an isolated floor. And here's where I posted my acoustic engineer's "OK" of that plan. With a little luck, I'll be cutting and jackhammering in less than 10 days.

--Keith

[PaulieSkiDrum]

Bump.....

Still hoping for response to last questions posted re: How much sound will be transmitted to ground thru 6" isolated slab? Will floor be weakest link still??

Thanks

[knightfly]

Sorry I let this one slip thru the cracks;

Re: the adjacent room- it will be storage/ ski tuning room w/ 1/2 bath. Not to be floating, walls all attached to current and added foundation walls.

If by "added foundation walls" you mean your new construction, specifically the sound room, this needs to be explored further - see next.

1. If we don't separate the two slabs won't sound travel thru drum room floor to exterior walls and ceiling in the storage room.

Yes - either your entire basement needs to be resting ONLY on the new, isolated slab or you will need two separated slabs. You do NOT want hard contact to continue from ANY part of the drum room to ANY part of the rest of the house.

This can be done by either two separate slabs, or by considering the other basement room as part of the sound room and having separate inner wall/ceiling frames for ALL the basement space. If there's not enough headroom for a separate inner ceiling frame, then resilient mounts of some sort will need to be used for hanging the layers of ceiling drywall.

2. Would we then split the slab by a 2'' space or something like that?

The drawing I posted assumed that the entire basement would be isolated from structure; you could also, if you don't ever intend the other room to be used for studio space, pour just the drum room's slab separate (1" minimum gap all around, footings under walls, foam board filler) - then, your drum room wall framing would rest on the isolated slab and your other room's wall frames would rest on the rest of the slab, which could be continuous with the NON-musical structure of the house.

3. I went crosseyed last nite loking for everything i could find in the forum re: slab floors. Many good comments were yours, and I'm a bit confused as far as weakest link theory ( obviously my damaged brain) If my walls and ceiling are STC of 65+, does my floor still become the weakest link if i do this monolithic floating slab?

No. If by some quirk of physics you still get flanking into the rest of the house (very unlikely unless a mistake is made) you can always do this

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=4013

4. How much sound will travel thru grade/ground to outside walls, etc
if we properly compact and prepare grade before slab goes in?

Very little. You'll be going from air to concrete to gravel to earth to concrete in order to reach the rest of the house's structure via the floor path.

5. Should slab be more than 4" deep?

Not necessary as long as thicker footings are used under all walls, as done in normal monolithic slab houses.

HTH... Steve