Reducing Transmission Loss & Impact Noise thru concrete

I have just bought over an old studio in a commercial building and have 2 main problems. There is no real proper treatment, have fished around this site, the ideal answer would be to build a floating studio, unfortunately the slab to concrete ceiling beam height is only 8ft, the ideal floating studio inside this will mean I will get close to scraping my head on the ceiling. Problem 1. Transmission loss through the floor slab, high level sound, drums, guitar etc transmitting through floor. The current floor is just carpet straight down on the concrete slab (unknown thickness probably no more than 4"), there is a "loud noise complaining tenant" one floor below. How effective would a floating floor only (without floating walls), silicone sealed to the 4 brick walls, be in reducing transmission loss. I would need to keep the floor air cavity to bare minimum. Was thinking cement board and plywood (5/8" or 3/4" thick each) sandwich sitting directly on strips of 1" polystyrene foam which is sitting on top of the existing carpet, with fibreglass insulation filling the cavity. How effective would this be? Problem 2. The ceiling has acoustic treatment only, some soft board and rockwool insulation, nothing with any significant density or mass. There is significant impact noise coming down through ceiling slab, the neighbour's floor above is painted concrete, I can hear every footstep, shuffle, pen drop etc I am trying to work out how I could hang some dense cement board (or similar) from the ceiling, silicone sealed on the 4 sides to each brick wall. If the hanging ceiling could work, any ideas on what product could be used to hang the ceiling frame and cemboard. How effective would this be? Problem 3. Have already invested to the max, need a cheap solution (don't we all) A floating studio will be far to expensive, so was trying to focus on the main problem floor and ceiling and ignoring transmission thru the walls, which is much less significant, the walls are thick plastered solid brick, which is working well. Any advice really appreciated Cheers (first time post and new member today) Michael

Welcome to the forum. You should wait for another poster to reply but... Good luck, there is no cheap way out of this :roll: The only cheap thing I can think of which will not be effective enough would be some risers for the floor which will reduce impact noise but will not stop the low end. Marc

Welcome to the forum. I have no answers for you -- hopefully Rod can chime in with some good advice for you. I do want to make one clarification for you: you want to increase transmission loss, not decrease it. Transmission loss = soundproofing. You want to decrease structure-borne flanking. --Keith :mrgreen:

Michael, i hate to tell you this - but we casn't get you from A to B. What you think isd the path that the sound is taking might be - or it might not be - the only way to know for sure is with an onsite visit. You need to hire an acoustician in your area to guide you. I can tell you that if you are right about your floor that the solution you suggest will not help you out to any degree. As far as your ceiling goes - this is a case where I would suggest that limp mass would probably help a lot - (MLV) and I would consider drywall before ever getting into trying to hand cement board ceilings. But first you need someone who is trained to check your space out and determine exactly what path the sound is taking. It would be a shame for you to spend hundreds or thousands of dollars and find out that nothing changed. Sincerely, Rod

Thanks guys for your responses. I am at a catch 22, I can't use the studio during working hours because of the people impact noises from my neighbors coming thru the ceiling concrete slab and my loud instrument noise going thru the ceiling and floor slab disturbing the neighbor's. Availability of qualified or trustworthy "Acousticians" in Malaysia is nil, would have to fly in someone, I can't afford that or can't afford to build a full floating studio. Kinda screwed, huh!! I am sure that the "worst" of the noise transfer is through the ceiling and floor concrete slabs as they are thin, rather than via the wall. I can literally hear a pen drop on the floor of my upstairs neighbor. I thought if I started with a floating floor only and a floating ceiling only this may help a little. If I need to improve it later when cashed up, I could bridge the ceiling and floor with walls - seems like the hard way around I know, but I have no choice, have invested to the max already. Rod, you said my suggested floor treatment will not work to any degree, is this because of the minimal air gap 1" or because of no (consistent) continuity up the walls to the ceiling? If I need to increase this air gap, what would be the recommended absolute minimum for reasonable performance? For a floating floor, could pieces or strips of polystyrene foam be used instead of rubber isolator's? Polystyrene is spongy, it compresses under weight. I understand that if it "bottoms out" then it is no longer is effective. Isn't it just a matter of establsihing the right distribution of isolator's so the floor is still afloat and mid compression cycle under normal conditions? When you say drywall, do you mean gypsum board (drywall is an unused term here) I thought cement board would provide better isolation because it is more dense and higher mass for the same thickness? Thanks Michael

Rod or anyone else for that fact ... any chance you could respond to my last post. I am starting to fret, can't use my studio at all during the day, guess that's why it was up for sale and was going cheap!! Thanks Michael

Junction wrote:

Rod, you said my suggested floor treatment will not work to any degree, is this because of the minimal air gap 1" or because of no (consistent) continuity up the walls to the ceiling? If I need to increase this air gap, what would be the recommended absolute minimum for reasonable performance?

Michael, It's both the air pocket and the mass........ or the lack thereof to be more prescise......... Isolating decks (to be effective) need enough rigid mass to acheive a center frequency of about 10Hz..... so we're talking a reinforced concrete slab a minimum 4" thick - then the air pocket - and the air is a very critical part of the equation - pouring a 4" concrete deck on top of an existing 6" deck will add about 3 STC - if you then raise that deck by 2" you will gain 22 STC.... add 2 more inches and your gain is another 3 STC....... The problem is that it's this compination of the 2 required to make this work ........ what you are suggesting would be fine for most impact noise - but not for airborne sound - for that you are just creating a drum head........... no where near the mass you need (around 115psf) to make it work. SO the magic number is around 6" - 2 of air and 4 of concrete - to make a floating deck work, and that is assuming that your existing structure could take that sort of load without collapsing.

For a floating floor, could pieces or strips of polystyrene foam be used instead of rubber isolator's? Polystyrene is spongy, it compresses under weight. I understand that if it "bottoms out" then it is no longer is effective. Isn't it just a matter of establsihing the right distribution of isolator's so the floor is still afloat and mid compression cycle under normal conditions?

I have no idea as to the density and other critical properties of this material or where exactly you would find data about it in this regard....... I do know that one of my concerns would be it's longevity - at what point would it colapse under a constant load? The problem with trying to find cheap alternatives to tested materials is that there is no one paying good money to test bad product........ or they teted it - and it doesn't work - which is why they don't market it and sell it....... Stick with what's tried and true..........

When you say drywall, do you mean gypsum board (drywall is an unused term here) I thought cement board would provide better isolation because it is more dense and higher mass for the same thickness?

Yes I mean drywall - and although I understand what you are saying - drywall is much cheaper mass than the otheer alternatives you speak of - so it isn't really cost effective......... Rod

...not to mention, it's much easier (relatively) to work with.

Thanks Rod and guys for your valuable advice, back to the drawing board now and dream up option 2! Cheers michael