how much sound leaks through concrete slab ceiling to residences above?

[subliminaleffect]

i'm considering putting a studio into a ground level retail space with four floors of condo residences above it. the building was built just a couple of years ago to earthquake conscious Los Angeles/California building codes.

i don't know how thick the concrete slab is that separates the retail space from the residences directly above but i would guess that it is substantial to support the four stories above. the ceiling slab is at least as thick as what is normally built above an indoor parking garage.

does anyone have any experience with how much sound (say, from a classic rock band playing together) leaks up through a concrete slab ceiling? the building owners are concerned about potential noise problems for the residences. i'd like to reassure them that the concrete slab will likely be sufficient mass to attenuate sound transmission (or at least, can be controlled with additional sound insulation at a reasonable cost).

does anyone have comparable experiences to share?

thanks.

[Sebg]

Sound doesn't "leak" through a building element unless there is a crack or hole.

Sound is "transmitted" through a building element.

Depending on how noisy or quiet the suburb is, indoor background sound levels within the apartments above could be as low as 20dBA, even during daytime. Let's say it is a more typical 35dBA.

Rock band is somewhere around 110dBA. A 200mm thick slab will provide around 50dBA of attenuation for this type of noise. That leaves 110-50=60dBA of sound transmitted into the apartments above. It means you need to find another (potentially) 30dBA of attenuation by building "room within a room" type studios.

That will not be a small task, nor a reasonable cost.

[boggy]

I don't know for USA, but some countries has elements, builded from clay (pictures attached), included in the slab, between floors, then there may not be always 50dBA of isolation, even if slab is (virtually) 200mm thick, because it's not homogeneous.

[andrebrito]

usually around 45 to 50 dB for a 300 mm slab

André

[Rod Gervais]

Originally Posted by subliminaleffect

i don't know how thick the concrete slab is that separates the retail space from the residences directly above but i would guess that it is substantial to support the four stories above. the ceiling slab is at least as thick as what is normally built above an indoor parking garage.

I would guess that you are mistaken..........

It would be a strange building if there were not a series of bearing points - with the necessary columns and beams (which might well be reinforced concrete) leaving the slabs to serve the purpose of providing horizontal shear strength (it is a flat membrane) as well as the necessary dead and live loads proscribed by code.

I am seriously doubtful that they would provide a slab capable of carrying the weight of fully loaded automobiles in motion for a residential slab..........

The info that you were already provided is probably close to what you're going to need....

Rod

[oldeanalogueguy]

my experience is that all the sound goes through the floor in apartments


some (to a lot) goes through the walls


never heard any sound from under me in an apartment


but if you had a rock band playing i can see where it could be heard above

depending on the design a lot of sound can go through the ductwork


and you cant soundproof that without screwing up the airflow for everybody who will complain and get you kicked out of the building when mgmt finds you were the one who did it.

[subliminaleffect]

thanks for the prompt responses.

the city ordinances limit noise to 65 dBA during daytime. i assume that would be noise transmitted outside to the exterior of the storefront though.

i would guess that the ceiling slab is going to be somewhere around 300mm (12" thick) so about 50dBA of reduction from the respondents.

i'd be willing to put in the cost of a layer of insulation and drywall in the ceiling. if that still isn't enough, i could stack an additional layer of drywall and resilient channel. surely that would be sufficient attenuation, wouldn't it?

anyone else with input?

Originally Posted by Rod Gervais

I am seriously doubtful that they would provide a slab capable of carrying the weight of fully loaded automobiles in motion for a residential slab..........

Rod, sorry my wording was misleading. i didn't mean that the thickness of the ceiling slab that separates the residences above could carry the weight of fully loaded automobiles.

i only meant that the ceiling slab is the same thickness as that which would separate a parking garage from residences above rather than another level of parking garage. so the ground floor consists of retail in the front of the building and parking garage in the back behind the retail with the concrete slab in the ceiling likely consistent in thickness for both the retail and parking.

[Sebg]

i'd be willing to put in the cost of a layer of insulation and drywall in the ceiling. if that still isn't enough, i could stack an additional layer of drywall and resilient channel. surely that would be sufficient attenuation, wouldn't it?

Please don't do this. The fact that you have suggested it means you don't yet know enough to proceed. I suggest you go out and buy Rod's book or get some more info.

never heard any sound from under me in an apartment

A friend just the other day told me that since the downstairs neighbours installed a timber floor, he DOES get noticeable sound - mostly footsteps but also other airborne sounds that he didn't notice before.

[Gohanto]

Originally Posted by subliminaleffect

the city ordinances limit noise to 65 dBA during daytime. i assume that would be noise transmitted outside to the exterior of the storefront though.

i would guess that the ceiling slab is going to be somewhere around 300mm (12" thick) so about 50dBA of reduction from the respondents.

i'd be willing to put in the cost of a layer of insulation and drywall in the ceiling. if that still isn't enough, i could stack an additional layer of drywall and resilient channel. surely that would be sufficient attenuation, wouldn't it?

Couple things, you can't really get "50 dBA" of reduction. dBA is a SPL weighting filter that applies to an overall sound level. You can get 50 dB of reduction at 500Hz, for example. If you want a single number average of what noise reduction a material offers, you look for its lab tested STC.

City noise ordinances, liquor commissions, department of health all have requirements depending on where you are, but they generally apply to noise measurements taken at the property line (i.e. the effect noise has on surrounding properties).

If they had a 12" slab, that'd be rare. 6-8" is much more common, although thickness of concrete beyond that only makes a minor difference.

Here's a test report on 6" concrete and it shows (further down) the octave band transmission loss (STC is airbourne, IIC impact insulation). Concrete, like nearly all materials, is much better at stopping high frequencies than low
http://www.kineticsnoise.com/arch/tests/pdf/B10.pdf

Granted, if there are leaks in the concrete from crack over time or mistakes during construction, that negates a lot of the noise reduction anyway.

You can try installing drywall, insulation, resilient ceiling, ect... and keep adding layers until the condo owners stop filing lawsuits.

Or, if you want to invest in making an actual studio, hire a consultant to test the existing STC of the floor/ceiling and make recommendations and detailed construction drawings on exactly what you'd need to do based on the SPL of a studio and the average noise level in the residences above you.

[Sebg]

Couple things, you can't really get "50 dBA" of reduction.

What else would you call a "reduction in the dBA level of the sound"?

I agree that we should not generalise the concept of "dBA noise reduction". However, I disagree with your literal statement. The Rw+Ctr sound insulation descriptor gives a very convincing ranking of partitions based on their ability to reduce the sound level by a dBA value that is equal to the Rw+Ctr value. Based on the ISO sound spectra shape.

The issue with using "dBA" is that it only applies to a specific sound source spectra shape. So a partition that reduces speech sounds by "50dBA" may only reduce rock band sounds by "40dBA". As long as the context is clear, which it is in this discussion thread (rock band) then it is valid to talk about "dBA noise reduction".

[gouge]

just on the slab,

it's not possible to guess whether the slab does or doesn't support the floors above. the colum grid could be in alignment between levels in which case the slab will be designed thinner (depending on span), or it could also form part of a podium or transfer slab which is used when you need to offset the column spacing from above to achieve a different design outcome. like with residential above commercial or a building above a carpark where the grids need to be different to achieve the design.

not sayng that's the case here but you just need to dig up a set of exisitng structurals to really know what you are dealing with.

that aside, thick slab is not really going to help with bass. it'll just make it easier for flanking paths to occur.

as mentioned above. room within a room will work. not tripple leaf construction if i understand your batten idea properly

not sure what approvals are needed but it's very achievable if you get someone that knows what they are doing. expensive but achievable.

[subliminaleffect]

Originally Posted by gouge

as mentioned above. room within a room will work. not tripple leaf construction if i understand your batten idea properly

not sure what approvals are needed but it's very achievable if you get someone that knows what they are doing. expensive but achievable.

OK, i've gone out and gotten Rod's book (excellent recommendation, by the way) and have been making my way through it over the weekend.

please let me rephrase my situation another way.

if i successfully get a room within a room design built of approx. 18' x 25' with a double door entrance, would a rock band playing at full tilt inside be attenuated enough so that any sound not contained by its walls/ceiling, could at least be insulated by the concrete slab ceiling (and additional insulating materials) from being heard at all by the condo residences above?

i haven't gotten a detail drawing of the concrete slab construction yet but assume it is 6" thick (and solid through the thickness). there is no ductwork penetrating through the ceiling slab, just one or two 3" or 4" pipes that insulating materials could be wrapped around and stuffed into the larger dimension coring.

ideally, i'd like to be able to assure the property owner that the room within a room design plus concrete slab ceiling/additional insulation together can effectively prevent the condo residences from being disturbed. then i can take the next step and get the actual construction drawings for the property.

many thanks in advance.

[avare]

Originally Posted by subliminaleffect

if i successfully get a room within a room design built of approx. 18' x 25' with a double door entrance, would a rock band playing at full tilt inside be attenuated enough so that any sound not contained by its walls/ceiling, could at least be insulated by the concrete slab ceiling (and additional insulating materials) from being heard at all by the condo residences above?

i haven't gotten a detail drawing of the concrete slab construction yet but assume it is 6" thick (and solid through the thickness). there is no ductwork penetrating through the ceiling slab, just one or two 3" or 4" pipes that insulating materials could be wrapped around and stuffed into the larger dimension coring.

ideally, i'd like to be able to assure the property owner that the room within a room design plus concrete slab ceiling/additional insulation together can effectively prevent the condo residences from being disturbed. then i can take the next step and get the actual construction drawings for the property.

Impossible to answer unequivaicably with more specifics. A reasonable approxiamtion, be it with coupling, is in fig. 5, lower right graph in IR 586. If you read through all of IR 586, you will see there great variation in TLs, even with just 2 main variables. For a plain 6" concrete slab, the STC is 52. The figure is misleading as the great LF TL is ignored. See pdf page 220 in IR 811 for more on the concrete.

Andre

[Rod Gervais]

Originally Posted by subliminaleffect

just one or two 3" or 4" pipes that insulating materials could be wrapped around and stuffed into the larger dimension coring.

California is not only earthquake conscious - it is also very fire conscious, and, where those pipes penetrate the concrete membrane separating floors there is supposed to be a rated tested fire separation assembly.....

Some of these assemblies make use of expansive materials intended to fill the remaining void when they are exposed to heat - and filling the void (in that case) would stop them from being able to act properly under fire conditions...........

If the building was constructed just 4 years ago - the owner should have the drawings, as well as the submissions made for fire separation assemblies of any and all penetrations - you need to make certain of what exists - you can always box out and seal on your side of the floor any pipes you wish - but filling the void in the case described above would not only be a code violation - it would put you at huge risk in the event that there was a fire which was not properly contained due to your actions.....

It sounds like it would be well worth your while to hire a local professional to guide you through some of this......

Rod

[subliminaleffect]

thank you for the link to additional reading on the subject.

if an unequivocal answer isn't possible, perhaps an anecdotal extrapolation like the following would help:

"we built a room within a room with walls of staggered studs and double layer drywall sandwiching green glue on the inside and outside. with a rock band going full tilt, the most that we ever heard was equivalent to a television set at low volume. the ceiling/flooring separating the room within a room from the apartment upstairs in my case was just typical wooden frame construction and the upstairs neighbors never heard anything so you could reasonably assume that your concrete slab ceiling should at least be as effective as this..."

does anyone have a (roughly) similar situation to share?

[DanDan]

sub, anecdotes and opinions won't help if you build this thing and it doesn't work.
However I will quote an anecdote related by my acoustics teacher.

Concrete apartment block. TV, conversation, etc. etc. on ground floor. Completely inaudible on 4rth Floor. Ground floor guy takes a hammer drill to attach a picture to the wall. Totally audible on the 10the floor.
Sound travels through solids much more efficiently than through gas. Much.
So Bass, Kick drum etc. will find their way through the floor slab, to the walls and up, unless the path is interrupted by a gap and or resilient break.
DD

[subliminaleffect]

Originally Posted by Rod Gervais

you can always box out and seal on your side of the floor any pipes you wish

Rod, thanks for the advice. your knowledge and experience are greatly appreciated.

Originally Posted by Rod Gervais

It sounds like it would be well worth your while to hire a local professional to guide you through some of this......

i am not adverse to hiring a professional (such as yourself). i would openly welcome solicitation from a knowledgeable and experienced professional who could offer me something like:

"from the general basics that you have provided so far, my initial assessment is that the sound of a rock band inside a properly constructed room within a room could be sufficiently contained by the 6" concrete slab ceiling (boxing and sealing any penetrations of the slab for piping on your side) so that the residences above would not hear anything. i could provide construction designs, estimates, details and instructions, accounting for site conditions, to accomplish this requirement. go ahead and get the as-built construction drawings and details so we can see what is there and i can provide an estimate for my services on your project."

not to put words in your mouth or on your keyboard...

[subliminaleffect]

Originally Posted by DanDan

Ground floor guy takes a hammer drill to attach a picture to the wall. Totally audible on the 10the floor. Sound travels through solids much more efficiently than through gas. Much.
So Bass, Kick drum etc. will find their way through the floor slab, to the walls and up, unless the path is interrupted by a gap and or resilient break.

DanDan, your teacher's anecdote helps a lot.

i'll be sure to account for properly decoupling the floor (and walls) of the room within a room from the overall floor slab then.

thanks. anyone else?

[avare]

Originally Posted by subliminaleffect

i'd like to reassure them that the concrete slab will likely be sufficient mass to attenuate sound transmission (or at least, can be controlled with additional sound insulation at a reasonable cost).

does anyone have comparable experiences to share?

Using blunt words, the slab by itself is not enough. You will need something like Kinetics Noise ICC with a mounting method shown in test report A13-d. It is not cheap.

Andre

[Rod Gervais]

Originally Posted by subliminaleffect

DanDan, your teacher's anecdote helps a lot.

i'll be sure to account for properly decoupling the floor (and walls) of the room within a room from the overall floor slab then.

thanks. anyone else?

A personal experience of mine - High rise hotel adjacent to a convention center - a promenade roughly 60' wide separated the 2 facilities (promenade level was located at the 3rd floor of both structures).

Beneath the promenade was a sub-section that provided a passageway between the 2 structures.

The structures were separated by an 8" air space - this with the exception of 1 concrete pile cap that provided support for a 14" thick concrete wall that was the end wall supporting the promenade - and a single steel column that provided support for the high rise. The concrete floor for the hotel lobby also rested on this pile cap.

We had some marble floor tiles that were chipped in the hotel lobby - the tile crew had to use small electric chipping hammers to remove the chipped tiles in order to install replacement tiles so we could open.

The closest tile to the pile cap in question would have been at least 40 away from the column.

I was standing on the promenade having a conversation and could clearly hear the chipping hammers - the sound was not coming from the closed doors leading into the hotel - which was the outside of a 6' deep airlock - but was clearly coming from an area outside of the hotel structure.

Upon investigating further I was pretty surprised to find that the sound was emanating from a pipe railing that formed a guard and handrail at the edge of the promenade where stairs led down to street level, as well as access to an exterior elevator that provided handicapped access to the promenade.

The rail was about 15' from the face of the hotel structure.... which means that the impact of the chipping hammers (and remember these were quite small electric units - we are not talking pneumatic jack hammers here) was traveling through the 14" thick reinforced concrete slab - up a 14" thick reinforced concrete wall - across a 24" thick reinforced concrete slab - and then causing the railings to ring....... I was standing outside about 35 to 40' from the rail in question and had no problem hearing clearly the sound pf the hammers.

One of the best examples of flanking I have ever experienced......

Rod

[petertjed]

I have a 30cm concrete floor, when i played white noise at 80db and I messured 50 db beneath the room,

Best regards,

Peter

[Rod Gervais]

Originally Posted by subliminaleffect

Rod, thanks for the advice. your knowledge and experience are greatly appreciated.


i am not adverse to hiring a professional (such as yourself). i would openly welcome solicitation from a knowledgeable and experienced professional who could offer me something like:

"from the general basics that you have provided so far, my initial assessment is that the sound of a rock band inside a properly constructed room within a room could be sufficiently contained by the 6" concrete slab ceiling (boxing and sealing any penetrations of the slab for piping on your side) so that the residences above would not hear anything. i could provide construction designs, estimates, details and instructions, accounting for site conditions, to accomplish this requirement. go ahead and get the as-built construction drawings and details so we can see what is there and i can provide an estimate for my services on your project."

not to put words in your mouth or on your keyboard...

Sub,

I would be happy to quote a design to you - however - it would require more than just the information you mention - it would require that you hire a local company to measure the existing isolation and determine what (exactly) was being transmitted through the floors - through flanking - ect.

Which is why I suggested a local company would be your best bet.

Drawings and details only provide me with the information necessary to determine the maximum isolation levels - which will never be the actual isolation levels. There is always a difference between lab tested assemblies and field tested assemblies - for a wide variety of reasons - I do know of reported cases where the designed weighted TL values versus those measured in the field have as great as a 30dB variance....

That puts a designer who's unable to have the actual data in the position of designing for the worse case - which can cost you a ton of money above what you may need to spend if you had the real numbers on hand.

Hate to talk anyone out of hiring me - but hate to burn a customer even more.

Rod

[subliminaleffect]

Originally Posted by Rod Gervais

Which is why I suggested a local company would be your best bet.

thanks for the honesty. do you know of any sound-proofing professionals in the Los Angeles area that you could recommend or even, how i would find one? i don't imagine Angie's List would have such a category.

i seem to be getting a pessimistic vibe from respondents in general. is the general consensus that building under a condo residence even with a concrete ceiling slab in between is never going to work without exorbitant cost (for the sake of argument, let's define it as $100/sq.ft.)?

or is it just collective experience and wisdom that dictates the (overly) cautious responses?

[Rod Gervais]

Personally I would not consider achieving that level of isolation in a condo environment for $100psf exorbitant - in fact I would consider myself lucky if I were able pull that off.

I know that construction costs on the west coast are greater than they are here on the east coast - and with the exception of simple starter homes (a basic residential box with no acoustic isolation to speak of - which can be constructed somewhere between $75 and $80psf) keeping construction costs below $100psf is one hell of a reach.....

Even if you were to do all of the labor intensive construction yourself - meaning framing, and drywall - plus all of the finishes - you can't do the line voltage electrical work - HVAC, fire alarm systems, heck - you can't even do low voltage wiring for the sound systems anymore without a license - you need a C-7 in California to do sound systems......

All of this makes pulling off $100psf one heck of a challenge.....

Rod

[DanDan]

My Irish Acoustics thing is in operation only a short few years. It coincided with a total flatline or worse in the economy here. Despite that, and consequently very little flow of biz, two of my clients had buildings which failed to serve purpose. Totally. One was rented but had a couple of hundred K invested in mods. The other cost a few mill. Both completely could not function due to the most simple basic reason. Location.
The first was a suite of rehearsal rooms. 8 small rooms, one large production sized. No-one seemed to notice the single block wall separating all of this from offices next door. Really.
The second was a multifunction community centre. They put a dance studio on the third floor. Wood frame floor. Well you should see that bounce up and down by inches, as viewed from the counselling offices directly underneath.
Really.
DD

[subliminaleffect]

Originally Posted by Rod Gervais

Personally I would not consider achieving that level of isolation in a condo environment for $100psf exorbitant - in fact I would consider myself lucky if I were able pull that off.

Rod, thanks for the discussion. my wording was unclear (again).

first, i only meant for the per square foot cost to also cover the (sound insulation) materials and installation. i didn't mean for it to include electricity, other wiring, lighting, HVAC, sprinklers, etc.

second, exorbitant was perhaps inappropriate. maybe prohibitive, instead? so the $45k cost to sound insulate a 450 sq.ft. room should make someone perhaps unused to regularly tossing around tens of thousands of dollars reconsider whether they've got the right building to begin with...

thanks.

[DanDan]

$45k cost to sound insulate a 450 sq.ft. room should make someone perhaps unused to regularly tossing around tens of thousands of dollars reconsider whether they've got the right building to begin with...

thanks.

You said it!

DD