California's Noise Insulation Standards for Multi-Family Residential Construction

Requirements for noise insulation are included in the design of all new multi-family dwelling units to be constructed in California after August 1974. Noise Insulation Standards are part of the California Administrative Code (Title 25, Section 1092) and are enforced by local building departments throughout the state. The standards apply to all new multi-family dwelling units, such as hotels, apartments, duplexes, townhouses, and condominium units. Detached single-family dwellings are specifically excluded.

The standards establish minimum requirements for the isolation of interior spaces from exterior noise and set minimum ratings for noise insulation of partitions between dwelling units. The community noise equivalent level (CNEL) of 45 dB is set as the maximum for intrusive noise from exterior sources. ASTM testing procedures for party wall and floor/ceiling system sound transmission provide the basis for setting minimum acceptable performance of separations between units.

Based on a study of numerous (over 200) residential projects, it has been found that a certification that the final design complies with the standards is generally required and provided as part of the consulting effort. Field tests are required when the sound transmission performance of the completed structure is questioned by the building official.

The paper provides a brief description of the standards, their enforcement, pitfalls and an assessment of their impact on residential construction in California.