Anyone familiar with STC 50 for residential floor? I just ran into a highrise condo project which requires STC 50 on 8" concrete slab without finishes above and under. Do you know any paint or spread that can provide STC 50 to that concrete slab?
The Sound Transmission Class (STC) of concrete is very high, and an 8-inch concrete floor will more than exceed the minimum STC 50 required by the code.
However, the problem with concrete floors is that they have a low Impact Insultation Class (IIC). This is the structural-borne sound made by objects on the floor surface, such as footsteps, sliding chairs, bouncing balls, etc. The code requires a minimum IIC 50, and an 8-inch concrete floor can only get an IIC 32 at best. The floor will need to be treated with some type of impact absorbing material such as carpeting.
Riga and needtolearn, thank you, The challenge is for a highrise afforable housing project without floor and ceiling finishes on bare concrete. The architect tried a special coating, but it didn't work, even it cost more than $2.50/sf. I told them we can put carpet on floor for the same unit price or about $24/sy, good carpet. So I think my challenge is to find some type of coating which has IIC 18 or more to make up 50 (32+18) correct? Thank you again
You need something on the surface to absorb the energy of the impact without transmitting it through the structure. A paint or coating (unless it is a liquid-type resilient flooring) won't give you that additional isolation.
If it isn't a tested assembly, then you'll probably need to field test it. In that case, all you'll need is an IIC of 45.
your alternate approach to carpeting/similar is to consider treating the ceilings (i.e. multi-component application using resilient channels or float/wire suspension system and either acoustic tiles or other material that has high vibration absorption potential...
i suggest you invest a few hundred dollars and get a consultation from an acoustic engineer in your area... it will be well worth the cost...
i'm not aware of any 'coating' that can come close to accomplishing what you need
Riga and Hil, thank you again, Developer of this affordable housing tested certain type of coating on another project but it failed. Design team is investigating other products, including Supertherm on ceiling, but I were told it can't be exposed. Any thought?
I'm not sure what the 'design team' is 'investigating'. You said high-rise, so the design team must have an architect. You said 'affordable housing'. This has been researched to death for decades with the same result. The 'standard' solution is: living areas get pad and carpet; bathrooms and kitchens get sheet goods with sheet padding beneath. HUD and FHA, along with other agencies, have specs for this. Neither of these are not 'expensive' solutions, as you have already noted. Every carpet/flooring subcontractor that has done multi-floor residential work has a spec for this. Every building department is familiar with these solutions. I'm at a loss to understand why you are having trouble putting this to bed. The cost of your time and the design team's time are greater than few hours need from an acoustic engineer for the necessary specs and details (also standard for these products, which are used, to my knowledge, across the country for this project type). hil
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