Sound Class Transmission Rating
From: Katie Henry (
Date: Sat, 7 Mar 2015 20:52:48 -0800 (PST)
I have the as-built drawings in PDF format for Eastern Village Cohousing. I see 
three places where walls are addressed:

. Cross-section diagrams of all wall types, including fire rating, UL design 
number, and GA file number (A6-2)

. Finish schedule showing what wall types are used in various locations 
(hallways, janitor's closets, individual unit bathrooms, etc.) (A6-3)

. Cross-section diagram of dwelling unit separation walls (A5-4)

I don't see any reference to STC or IIC numbers, but I don't know a lot about 
that aspect of construction. I'm happy to send you the three sheets if you want 
to try to figure them out.

As Jessie mentioned earlier, EVC is a rehab of a 1950's office building with 
six-inch concrete floors, so sound transmission between floors is negligible. 
Sound transmission between units is minimal, with a few exceptions, such as the 
two-story units where the spiral stair is attached to a common wall or in cases 
where residents have attached things to a common wall. My impression as 
building manager was that most residents were very happy with the level of 

I'm glad you're taking sound-proofing so seriously. I walked away from a condo 
purchase the day before closing because the upstairs neighbors came home during 
my final walk-through and I could hear every footstep and every word they said. 
Cost me $20,000, and I didn't regret it for a minute. I couldn't have lived 
with it.

Katie Henry

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