SOUND TRANSMISSION CLASS (STC)
In residential walls and ceilings there should be an STC of 45 or higher for partitions and floors/ceilings separating living units from other living units, public spaces, and service areas.
2 Types of Sound Transfer with Solutions to buffer sound transfer:
- Airborne Sound Solutions – TV, talking, etc.
- Caulk and seal all penetrations. An amazing amount of airborne sound can get thru tiny openings.
- Ceiling fixtures should be surface mounted, not recessed, to reduce penetrations.
- It is incorrect to assume that higher density insulation means improved sound insulation. Tests have shown that insulation thickness is the most important property when describing a cavity absorbing material. Thickness affects the sound transmission loss at most frequencies and therefore affects the STC rating.
- Impact Sound Solutions– Sound traveling a path through solid structure such as hearing your neighbor walk in the unit above. This is the most common and the most difficult to fix.
- Cushioning the impact with carpet and pad is one of the most effective methods of isolating impact noise.
- The use of fiber glass insulation with a resilient ceiling attachment will increase the sound insulation for both airborne and
impact sound.
Here is a GUIDE with building details to create various STCs: WALLS_Guide for Residential Sound Control