Boston Construction Noise: The Limits at Your Lot Line

If a site opens up next to a home you own in Boston, the question that decides it is where the reading gets taken. The city’s rules measure at the lot line of the affected property, so the number that settles a complaint is the one arriving at your wall.

Two separate tracks

The Regulations for the Control of Noise in the City of Boston, adopted by the Air Pollution Control Commission, split the problem. Regulation 2 covers the use or occupancy of a lot and the noise it produces, and it runs off a table of zoning district standards. Regulation 3 covers construction sites and construction devices, which Regulation 2 expressly leaves alone. Reading a construction complaint against the zoning table is a mistake I see often, and it points at the wrong number.

The zoning district standard

The table sets maximum allowable octave band sound pressure levels at nine center frequencies, measured at any lot line, and gives a single number equivalent for each column. For a residential district that equivalent is 60 dBA during daytime and 50 dBA at all other times. Daytime is defined as the period between 7:00 AM and 6:00 PM. Separately from the regulation, the city describes regular construction hours as 7 a.m. to 6 p.m. on weekdays. Business columns sit at 65 dBA, and an industrial district at 70 dBA.

The construction standard

Regulation 3.1 makes it unlawful to run construction devices if the operation emits noise, measured at the lot line of the affected property, above an L10 level of 75 dBA where that lot is in residential or institutional use. The same row carries a maximum noise level of 86 dBA. Business or recreational lots sit at 80 dBA and industrial at 85 dBA, and a public way is treated as industrial use.

What L10 actually means

L10 is the A-weighted sound level exceeded ten per cent of the time. Regulation 3.2 spells out the method: a reading every ten seconds until one hundred observations exist, with readings spoiled by an outside source such as an aircraft overflight thrown out and the period extended until one hundred valid ones are in hand. The L10 level is the tenth highest of those. It’s a reading of a working morning rather than one bang.

The background test

There’s a second step that protects a site on a loud street. If the person taking the measurements judges that outside sources are contributing significantly, the procedure is repeated with construction inactive to establish the background L10 level. The construction L10 has to exceed that background by 5 dBA before Regulation 3.1 is considered violated.

The carve-outs

Street excavation, grading or repair, and utility street work installation or repair are handled by Regulation 3.3, with a ceiling of 86 dBA at the stated measuring distance from the device. Regulation 3.4 then takes impact devices outside both Regulation 3.1 and Regulation 3.3, and the definitions name pile drivers and paving breakers among the first of them, leaving them to the general prohibition in Regulation 1 and any permit conditions. Regulation 3.3 also excuses a device used in emergency work to restore utility service, provided it is brought into compliance within a day or is not reused in the city until it does. On the residential side, intermittent or occasional daytime use of homeowner’s light residential outdoor equipment, which the definitions illustrate with lawn mowers, garden tools, riding tractors and snow blowers, is outside the zoning table, as is commercial service equipment such as chain saws and log chippers.

Who to call

The City of Boston’s Noise in Boston page routes building construction noise to Inspectional Services during hours. After hours it asks you to check the afterhours permit database first, and to call 311 or Inspectional Services if no permit turns up. Noise that is a disturbance of the peace goes to the police line, restaurant and entertainment venue noise to Entertainment Licensing, trash pickup noise to Public Works, and aircraft to the Massachusetts Port Authority. The Boston Public Health Commission administers the ordinance.

Selling or renovating nearby

Two practical notes. If you’re the one renovating before a listing, the hours and the lot line are what draw calls, and a conversation with the abutters ahead of time costs nothing. If you’re buying near an active site, the permit tells you more than the noise does. Looking at a place in Greater Boston with construction on the block? Send me the address and I’ll pull what’s permitted around it. Diana Kim, REALTOR®, eXp Realty.