Code: This standard rates a building's
ability to block outdoor noise impact (typically from aircraft noise).
Enforcement: Some cities and counties
General Information: This code applies to structures in the vicinity of Air Force bases or airports (in some cities) and is designed to protect any building from excessive aircraft noise. The county or municipality in which the Air Force base or airport is located typically enforces this standard*.
When applicable, building permits will not be granted until acceptable
NLR ratings are demonstrated. All Air Force bases and airports have
noise contour curves, which are established by a Federal Aviation
Regulation (F.A.R.) Part 150 noise study**. You must meet different
NLR depending upon which noise contour curve your structure resides
in. For example, a building between Ldn 65-70, must meet an NLR
of 25 dB. Its typically assumed that a standard construction
will meet an NLR of 20. Within noisier areas, you must upgrade the
isolation in order to comply.
The U.S. Air Force has established sound isolation standards designed
to provide outdoor-to-indoor NLR of 25, 30 and 35 (found in the
U.S. Air Force Recommendations for Insulation of Residential
Structures Against Aircraft Noise). Although following the Air
Forces suggestions will help ensure compliance, you are still
able to comply without following their step-by-step recommendations,
provided a professional acoustician certifies the plans.
* Residents in some cities might qualify for state-funded aid to upgrade their homes to improve the NLR if they live within a certain distance from a public airport.
**As part of this study, the noise contour curves must be calculated and documented.