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Common Types of Noise Disturbance

Click the tabs to the right to read about the most common types of noise disturbances in Montgomery County.  Visit the Noise Disturbance page or the Noise Ordinance page for more information on how noise disturbance is classified and the details of the noise control ordinance.


Music and PA Systems

Outdoor amplified sound can be a pleasurable experience at a restaurant, music event, or party, but it can create noise problems for surrounding neighbors if not adequately controlled. Other forms of amplified sound, such as an outdoor PA system used at a place of business or sporting event, can be another source of unwanted noise, which can sometimes carry a considerable distance from the source.

All outdoor amplified sound must comply with the decibel limits established in the Noise Control Ordinance, which are measured at the nearest residential receiving property line. The established limits are:


Maximum Allowable Noise Levels in Montgomery County


Daytime:  7am-9pm Weekdays; 9am-9pm Weekends and Holidays

Nighttime:  9pm-7am Weekdays; 9pm-9am Weekends and Holidays

Non-Residential Areas


67 dBA


62 dBA

Residential Areas


65 dBA


55 dBA



Yard Maintenance and Leaf Blowers

The Montgomery County Noise Control Ordinance limits the hours of the day during which power tools and lawn and garden equipment may be operated.

  • Commercial equipment operation may not begin until 7 a.m. weekdays and 9 a.m. on weekends and holidays.

  • All residential yard care and landscaping activities must comply with the standards in the Montgomery County Noise Ordinance.


Leaf Blower Noise

The primary noise concern related to landscaping and yard care is the use of leaf blowers that might cause unnecessary and unusual noise disturbances.

A leaf blower is defined as any portable device designed or intended to blow, vacuum, or move leaves or any other type of debris or material by generating a concentrated stream of air. Leaf blowers include devices or machines that accept vacuum attachments.

In July 1989, after extensive discussion, testimony, and public hearings, the Montgomery County Council amended the County Noise Ordinance (Chapter 31B, Section 31B-11, Montgomery County Code) to specifically regulate noise from leaf blowers. The amendment became effective July 1, 1990. It was reconfirmed and included in the comprehensive revision of the Noise Control Ordinance that became effective March 13, 1996.

Leaf Blower Standard

A person must not sell, buy, offer for sale, or use a leaf ​blower at any time that has an average sound level exceeding 70 dBA (A-weighted decibels) at a distance of 50 feet.

This requirement is in addition to any other noise level or noise disturbance standard that applies under the Noise Ordinance. The Department of Environmental Protection (DEP) must apply the standard in accordance with the most current leaf blower testing standard of the American National Standards Institute (ANSI).

Manufacturers, distributors and retailers are encouraged to submit design and performance data to DEP on all units offered for sale in Montgomery County to demonstrate compliance with ANSI standard. They are further encouraged to conform to the labeling recommendations of the ANSI standard. Without such information and labeling, DEP may order suspension of sale of a specific unit until such test and performance data is obtained.

DEP may inspect—and on its request a person must produce—any leaf blower that is sold, offered for sale, or used in the county, to determine whether the leaf blower complies with the law. A person who relies in good faith on a manufacturer's written representation of the sound level of a leaf blower that has not been modified is not subject to a penalty for violation.

It is the intention of DEP to facilitate voluntary and amicable compliance with this ordinance section among all concerned. However, upon conviction, violators are subject to a civil fine of $500 for the first offense, $750 for subsequent offenses, and other relief as allowed by law.


File a Complaint

Emergency Standby Electric Generators

Commercial buildings are required to have emergency standby generators to operate emergency lights, elevators, fire alarms and fire pumps during power outages. Also, in recent years it has become increasingly popular for homeowners to install emergency standby generators. Consequently, the number of noise complaints related to emergency standby generators has been steadily increasing.

Problems may be avoided through careful planning, design, equipment selection and installation. Almost all manufactured products, including generators, have noise performance specifications. Potential noise sources that can operate on a 24-hour basis, such as standby generators, are required to meet Montgomery County's more restrictive nighttime standard of 55 dBA (A-weighted decibels) at the nearest receiving residential property line.


Things to Consider when Planning for the Installation of an Emergency Standby Electric Generator:

  1. Purchase the quietest generator available. It is much easier to start with equipment that can meet the standard than try to retrofit equipment with noise suppression features later.

  2. The physical location of the generator should be chosen to minimize noise impacts to both on-site occupants and all nearby neighbors.

  3. The general rule of thumb is every time you double the distance from a point noise source you get a corresponding 6 dBA drop in sound pressure. Therefore, if the level is 62 dBA at 7 meters it would be 56 dBA at 14 meters, and 50 dBA at 28 meters, and so on. Noise measurements are typically taken from a complainant’s closest property line.

  4. Schedule the recommended periodic testing of generators to occur at times when building occupants and nearby neighbors are least likely to be disturbed.

  5. The regulations grant a 2.5 dBA allowance for any possible inaccuracies in the sound meter or the operator. The actual nighttime standard is therefore 57.5 dBA or lower.

  6. If distance is a restricting factor, consider constructing a noise barrier to reduce the sound. Several commercial "noise attenuation" or "acoustic enclosure" solutions are available.

The Montgomery County Noise Control Ordinance was first passed by the County Council in 1975, and the ordinance was revised in 1996. DEP works with the Department of Permitting Services to distribute noise information with applications  for permits to install electric generators.  Ultimately it is the property owner’s responsibility to ensure the noise from their generator is in compliance with the nighttime decibel standard.

DEP does not make recommendations for makes and models of equipment that comply with the current nighttime decibel standard.


For more information, email DEP at or contact 311.

File a Two-Party Noise Complaint


Questions about Electric Generators and Air Quality? Visit our outdoor air quality page.

Trash Collection

Trash companies and their employees are not allowed to collect solid wastes and recyclables in Montgomery County before 7 a.m. (9 a.m. on federal holidays and Sundays) or to collect after 9 p.m. on any day (Monday through Sunday, including federal holidays). However, collections may be made at any time from business establishments such as commercial, industrial, institutional, or other nonresidential use structures provided that there is no residential structure within 500 feet of the collection point.


If you experience a trash collection noise problem during quiet hours, contact 311.

Parking Lot Cleaning

Commercial parking lot cleaning activities employ vacuum trucks and leaf blowers to collect and remove debris.  Owners and property managers of commercial buildings and retail establishments generally prefer lot cleaning activities be performed after their business hours. This often times means that lot cleaning activities are occurring after 9 p.m. during quiet hours, and sometimes within close proximity to residences.

The maximum allowable sound levels, measured at the nearest receiving property line, are as follows:


Maximum Allowable Noise Levels in Montgomery County


Daytime:  7am-9pm Weekdays; 9am-9pm Weekends and Holidays

Nighttime:  9pm-7am Weekdays; 9pm-9am Weekends and Holidays

Non-Residential Areas


67 dBA


62 dBA

Residential Areas

(Mixed Used Areas are Treated as Residential)


65 dBA


55 dBA


While it is understandable that lot cleaning contractors may have to service a particular location during nighttime hours, there are things that can be done to minimize the impact of noise on nearby residences, which includes:

  • Clean areas closest to residences as early as possible.

  • Use non-motorized hand cleaning methods on areas closest to residences.

  • Incorporate noise control considerations when bidding and/or soliciting new contracts.

  • Communicate with the surrounding community.

  • Select equipment for its low-noise-emission design.

For more information, email DEP at or contact 311.

File a Two-Party Noise Complaint

Construction Noise

Construction and development projects are by their nature not quiet. However, with careful planning and operation, it's possible to minimize potential noise disturbances from construction activities. Construction workers, contractors and engineers, should be aware of how activities are regulated under the Montgomery County Noise Control Ordinance. 

If after reading this information you believe a construction site is in violation of the Montgomery County Noise Control Ordinance, click here to File a Two-Party Noise Complaint.

                                   Image of Construction

Construction Noise Basics

Virtually all potential noise sources that operate permanently or semipermanently can be designed or controlled to meet the receiving property line standard. Likewise, potential sources under human control, such as electronically amplified sound, can be designed to meet the ordinance requirements.

Noise from some construction activities, however, is difficult, if not impossible, to control to the receiving property line. This is because the engineering design and technical controls that are effective on stationary sources aren't practical or reasonable for a temporary, often mobile, noise source.

The Noise Control Ordinance, therefore, contains certain standards specific to construction noise. DEP has several tools available to help mitigate and regulate this potential source of disturbance.


Construction Noise Exemptions and Standards

The Montgomery County Noise Control Ordinance defines construction as temporary activities directly associated with site preparation, assembly, erection, repair, alteration, or demolition of structures or roadways. Construction noise levels must be measured on a receiving property, but no closer than 50 feet from the noise source.

Notice to Contractors

From 7 a.m. to 5 p.m. weekdays, construction noise levels must not exceed:

  • 75 dBA without a Noise Suppression Plan
  • 85 dBA with a Noise Suppression Plan

See the Guidelines for further information on a Noise Suppression Plan (PDF, 488KB)

At all times other than 7 a.m. to 5 p.m. weekdays, the general ordinance guidelines in the Noise Control Ordinance must be met. The following table provides a summary of the noise standards for construction activities:

Construction Noise Standards By Time of Day
Time of day Residential Nonresidential*
   7 a.m. to 5 p.m. (exempted hours) 75 dBA (85 dBA with a Noise Suppression Plan) 75 dBA (85 dBA with a Noise Suppression Plan)
   5 p.m. to 9 p.m. (daytime hours) 65 dBA 67 dBA
   9 p.m. to 7 a.m. (nighttime hours) 55 dBA 62 dBA
 Weekends and Holidays**    
   9 a.m. to 9 p.m. (daytime hours) 65 dBA 67 dBA
   9 p.m. to 9 a.m. (nighttime hours) 55 dBA 62 dBA


 *In most circumstances in the County, the receiving property will be considered residential.

   ** The U.S. Office of Personnel Management has a list of federally recognized holidays.


Be Aware! Construction activities are also subject to the "Noise Disturbance" provisions of the ordinance. Although a noise disturbance could conceivably occur at any time, it is most likely to happen during nighttime hours. The following are examples of noise disturbances:

  • The delivering materials or equipment.

  • The Loading or unloading in a residential area.

  • The operating of construction equipment with audible backup warning devices.

The County mails copies of the revised ordinance upon request. If you have questions or comments, contact 311.


Tools for Regulating Construction Noise

In addition to the Noise Control Ordinance, DEP has several mechanisms for controlling and regulating construction noise.

Noise Suppression Plan

A Noise Suppression Plan is a written plan to use the most effective noise-suppressing equipment, materials, and methods appropriate and reasonably available for a particular type of construction.

Several construction activities, such as pile driving and hoe ramming, might inherently exceed 75 dBA, depending on the circumstances. In those cases, the Montgomery County Noise Control Ordinance allows up to 85 dBA, provided a Noise Suppression Plan, approved by DEP, is implemented. Essentially, these plans require the best reasonably available control technology or strategy. They might involve equipment selection, scheduling, and temporary noise control devices to block or absorb the sound.

Read the full text of the Montgomery County Noise Suppression Plan Guidelines (PDF, 488KB) to learn more.

Approved noise supression plans:



Temporary Noise Waiver

Occasionally, public works construction projects are done during hours that fall outside the County-designated normal construction hours of Monday through Friday 7 a.m. to 5 p.m. These projects are usually done in response to directives by state and local agencies to address traffic congestion and pedestrian safety issues. The Montgomery County Noise Control Ordinance allows for the issuance of a Temporary Noise Waiver to allow after-hours and nighttime construction projects if the benefit to the public offsets the noise the event will create in excess of the established limits. Refer to the application form and fee schedule below, and allow 30 days for the processing of your Temporary Noise Waiver application.

The following fees apply for exemption applications:


Fees for Temporary Noise Waivers
Activity Source Hearing (C)
Single Source (A) Multiple Source (B)
Residential, single-family $50   $100
Residential, all others $230 $230 + ($25 per source/site) $500
Construction (all types private) $350 $350 + ($25 per source/site) $500
Commercial $350 $350 + ($25 per source/site) $500
Industrial $350 $350 + ($25 per source/site) $500
Transportation $350 $350 + ($25 per source/site) $500
Government $350 $350 + ($25 per source/site) $500



Active Nighttime Construction Projects:







Overnight Work Will Close Lanes on MD 355 and Cedar Lane Through Late Fall


(September 20, 2016) – The final phase of roadwork for the MD 355 (Rockville Pike)/ Cedar Lane/West Cedar Lane intersection widening project in Montgomery County starts early next month.  Beginning in early October (weather/schedule permitting), the Maryland Department of Transportation’s State Highway Administration (SHA) will pave all turn lanes and through lanes at the intersection.   Weather permitting, the work should be complete by late fall.


The final resurfacing work includes:

  • Removing the top layer of asphalt;
  • Resurfacing all traffic lanes
  • Applying temporary lane markings


Crews are permitted to close lanes on MD 355 Sundays through Thursdays between 8 p.m. and 5 a.m. additionally, and weekdays 9 a.m. to 3 p.m.  Equipment used for construction may be disruptive. More than 55,000 vehicles drive through this intersection daily.


“We ask that all drivers and pedestrians be alert and look for the orange - the color of construction signs, cones, barrels and fencing,” said SHA District 3 Engineer Brian Young. “Sidewalk, bicycle and pedestrian path users will be able to safely pass through the work zone by following signage that directs them around closed paths or sections of sidewalk.  SHA appreciates the cooperation of the public as we work to complete this project.” 


This improvement is part of Base Realignment and Closure (BRAC) intersection projects in Bethesda.  For the latest real-time travel information, log onto or call 1-855-466-3511 using a hands-free device while driving. Those with questions may contact Mr. Robert Shoemake, SHA Project Engineer, at 301-362-1580.


Tips for Construction Site Managers

Useful tips learned from previous construction projects include the following:

  • Incorporate noise control considerations in all phases of project design and planning.

  • Communicate with the surrounding community early and often. Put a human face on the project and the company. Let people know what's happening and, most importantly, when it should be over. People are more tolerant when they know what to expect.

  • "Buy quiet----Rent quiet." Select equipment for its low-noise-emission design. When renting, specify the quietest equipment available, using the Noise Control Ordinance requirements as a guide. Low-noise equipment is often of better quality and durability. Most manufacturers can provide noise emission specs.

  • Internal combustion equipment should be equipped with proper, well-maintained mufflers. In particular, use "critical" mufflers in noise-sensitive areas. Keep access doors and hatches closed when the units are in operation, and operate all equipment at the minimum level necessary to get the job done. (It saves fuel too!)

  • Whenever possible, schedule the more noise-intense activities for less intrusive times, such as mid-morning to mid-afternoon.

  • Construct portable barriers around noisy non-mobile pieces of equipment, using readily available materials.

  • Use lawful alternatives to factory-installed backup beepers, such as flagpersons, "Smart Alarms," or video systems.

  • Purchase a sound level meter for self-monitoring and documentation.

  • "Work quiet." Equal to all of the above is the awareness that noise control is an important part of the job. Everyone likes a good neighbor. Managers and supervisors should communicate that noise control is part of the job.

  • Noise suppression measures can be fabricated on-site using materials at hand. Also, many equipment manufacturers provide silencing packages, both design and retrofit.

Proactive and reasonable control of construction noise results in more content communities and successful, on-schedule projects with a minimum of hassle due to noise. It also removes the inconvenience of civil penalties, abatement orders, or stop work orders.


Calculating Sound Intensity

Noise emissions from all mechanical equipment must be expressed, in A-weighted decibels (dBA), measured at a stated reference distance. It's your responsibility to calculate the estimated sound intensity (in dBA) to ensure that it complies with the Montgomery County Noise Control Ordinance. The following guidance can help you:

  • As a general rule, sound from a stationary source will diminish approximately 6 dBA with each doubling of distance. For example, if the sound intensity is 75 dBA at 25 feet, it will be 69 dBA at 50 feet and 63 dBA at 100 feet.

  • Because of the logarithmic nature of the decibel scale, if two sources of equal sound intensity are placed in close proximity to one another, the net increase will be 3 dBA. However, if there is a difference of 10 dBA or more between the two, the lesser source will have no effect on the overall level.

These estimations are especially useful in determining equipment or facility placement (e.g. loading docks), or in the design of engineering controls. All calculations and assumptions should be submitted to the reviewing authority.

Note: Most equipment manufacturers, and especially those who produce or market in Europe or Asia, have detailed noise performance specifications for their products.