Soundproofing A Standby Generator
Soundproofing a standby generator is becoming a more frequently encountered challenge when it comes to soundproofing. Standby generators have become increasingly popular in recent years with home and business owners after periods of prolonged power outages due to natural disasters, such as hurricanes, tornadoes, floods, fires and earthquakes. One of the challenges faced by generator owners relates to the high levels of noise that generators make. There is no such thing as a quiet generator, and owners are faced with paying more for a full-featured generator set that may operate quietly verses paying less for a louder generator. This trade-off is troublesome since a standby generator will only be used for emergency power over several days and nights as infrequently as once or twice per year.
Generator Decibel Levels
Generators operate at a fixed RPM, however, they develop noise across the audible spectrum depending on the size and type of motor, the number of cylinders, the design of the radiator fan, the configuration of the inlet, the type of exhaust system and amount of soundproofing in the enclosure. Most standard generator enclosures are adequate weather enclosures, but they may not contain adequate soundproofing. As a result, standby generators will typically emit noise in the 65 to 80 dB range, which may exceed most community noise ordinances. Generator owners are therefore left with very few viable alternatives to reduce noise for their standby generators.
Sonic-Shield acoustical engineers have worked extensively to develop affordable noise control solutions for standby generators. We typically recommend the use of an auxiliary sound dampening barrier fence that can be built around the generator. These fences can be made to look attractive and blend in with existing homes, buildings and landscaping. Such a fence can be fabricated and assembled by a typical home or business owner, using our soundproofing materials together with fencing, lumber and other building materials that can be purchased from a hardware store. Our general recommendations include the following:
- Internal Space – We recommend that the generator owner consult with the manufacturer to determine the minimum distance between the inside of the fence and the generator. Generally, manufacturers recommend a minimum clearance of 18” to 24” around the generator to ensure adequate room for access to the generator and proper air flow.
- Height – We recommend that the height of the fence be a minimum of six feet tall or twice the height of the generator, whichever is tallest. The six foot height is the minimum height required to block noise from a listener at ear level, although we recommend heights of eight feet or more, depending on the height of nearby houses and the topography of the site.
- Fence Materials – The fence can be constructed using a standard wooden fence which will provide a very aesthetic structure that can blend in with the house and yard. Some generator owners may opt for a cinderblock wall or chain link fence. Whatever materials are used, we recommend the use of heavy-duty materials in order to support the weight of additional sound attenuation materials that will be added to it.
- Sound Barrier Materials – On the inside of the fence, between the support poles and wooden fence panels, we recommend the use of Sonic-Shield Noise Barrier, which is a sheet of mass-loaded vinyl with superior noise blocking capabilities and a density of one pound per square foot (STC=26). The noise barrier should be installed loosely on the inside of the fence and cover the fence from top to bottom. Special consideration should be given at the bottom of the barrier to ensure that sound does not leak out of the bottom of the enclosure.
- Sound Absorption Materials – On the inside of the fence, on top of the Sonic-Shield Noise Barrier, we recommend the use of Sonic-Fiber absorption insulation. These materials are hydrophobic (i.e., they shed water) and come in rigid sheets that are 2” thick. Sonic-Fiber has an NRC of 1.0, which means that it will not reflect noise from the generator, which will eliminate acoustical reverberations which may amplify within the fence structure.
We Can Help
Sonic-Shield engineers can assist home and business owners by providing technical advice and design recommendations for the construction of a noise dampening fence for their standby generators. Once a fence design is developed, Sonic-Shield can “kit” and deliver all of the materials and accessories needed to properly soundproof the generator.