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Sound Transmission

Sound Transmission

Sound Transmission

(OP)
I've got an electrical engineer telling me that his refridgeration room on the elevated mezzanine level needs to have solidly grouted CMU walls to reduce sound transmission.  They're also crying about headroom below the mezz, too.  My mezzanine steel framing is already rather deep due to the required live loads.  And they will only get deeper with a solid CMU wall and L/600 deflection limits.

Now, he said he'd like to get a 12" CMU wall.  I think a 12" metal stud wall with batt insulation would be a better option, at least structurally.  Does anyone know about sound transmission through CMU vs. Insulation or any other product?

If there's tables for dead loads, are there tables for sound transmission through different media?

RE: Sound Transmission

I was just recently involved in a movie theatre project.  Sound transmission between theatres needed to be controlled.  The construction detail between theatres was a double metal stud wall with an air space between them.  There was also some detailing that had to be done at the roof.  The roof deck had to be broken between theatres.

RE: Sound Transmission

The classic "Wood-Frame House Construction" by the US Dept. of Agriculture (Handbook No. 73) has a 6 page chapter on "Sound Insulation". It states that "the resistance of a building element, such as a wall, to the passage of airborne sound is rated by its Sound Transmission Class (STC)". This book is very affordable on Ebay.

www.SlideRuleEra.net

RE: Sound Transmission

Can you use upset beams to provide a deeper beam without infringing on headroom? In other words, raise the beams up to the top of the slab or even higher. If you raise them above the top of the floor, you may have to cope them at door openings.

RE: Sound Transmission

(OP)
Unfortunately, there is a hallway around the refridge room, making the top flanges a tripping hazard!

I'm using the steel and concrete slab for composite construction, also.

From my research so far, it appears that a stud wall with batt insulation and solid CMU provide about the same STC value.

RE: Sound Transmission

Hi there,

Yes there are tables in the back of most district codes.  I don't have but I can tell you  you a bit about STC and code requirements.

The Ontario building code requires an STC of 50 between dwellings and and STC of 55 if the dwelling abuts an elevator shaft or garbage chute.

The american codes should be similar.  I know wood stud (double wall) with insulation will meet an STC of 50.  You can't use wood stud because you'r ina non-combustible building.  I'm sure metal stud/drywall and insulation will get you to 50 or 55.  

The concrete block won't be any good without 2 coats of oil paint on each side which makes me think the 12" CMU request is a not a complete idea.

I can't get you the details because I'm out of town for a while.  

I suggest you put this back to the architect.  Be careful with sound transmission.  It often leads to complaints from occupants which can become a major problem or lawsuit later.  

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