CNEL NOISE MITIGATION MEASURES

General

Per Section 1208A.8.5 of the City of Los Angeles Building Code, residential buildings located within a municipal airport noise boundary shall comply with prescriptive standards established by the Los Angeles County Building Code Manual (LACBCM) for mitigation of interior noise levels due to the airport. There are three municipal airport noise boundaries designated by the "Community Noise Equivalent Level" (CNEL) data element with the values, "65 dB < 70 dB", "70 dB < 75 dB" and "75 dB +". The Los Angeles Department of Building and Safety (LADBS) Electronic Permit System (e-Permit system) provides four types of work where compliance with these measures is required if the residential building is located within a CNEL noise boundary. These types of work are:

  1. Replace window(s)
  2. Replace door(s)
  3. Replaced damaged wood framing
  4. Chimney repair

The noise mitigation measures required for each type of work are shown below.

Replace window(s)

For residential buildings located in a CNEL noise boundary, all replacement window(s) must comply with the standards summarized in the table below. Click on each "CNEL Noise Boundary" hyperlink to review the complete text of the prescriptive standards.

CNEL Noise Boundary Prescriptive Standards Established by LACBCM for Mitigation of Interior Noise Levels When Window(s) Are Replaced
65 dB < 70 dB
  1. Openable windows shall have a minimum Sound Transmission Control (STC) rating of 35dB.
  2. Fixed windows shall be glazed with minimum of 1/4-inch glass and be set in non-hardening glazing materials.
70 dB < 75 dB
  1. Openable windows shall have a minimum STC rating of 40dB and shall have an air infiltration rate of no more than 0.5 cubic feet per minute according to ASTM E-283.
  2. Fixed windows shall be shall have a minimum STC rating of 40dB and be set in non-hardening glazing materials.
  3. The joint between the wall opening and windows shall be continuously filled with glass fiber insulation and the exterior cover trim shall be continuously caulked to seal the joint.
75 dB +
  1. Openable windows within stucco or masonry walls shall have a minimum STC rating of 40dB and shall have an air infiltration rate of no more than 0.5 cubic feet per minute according to ASTM E-283.
  2. Openable windows within wood siding or lightweight exterior cladding walls shall have a minimum STC rating of 44dB and shall have an air infiltration rate of no more than 0.5 cubic feet per minute according to ASTM E-283.
  3. Fixed windows shall be shall have a minimum STC rating of 44dB and be set in non-hardening glazing materials.
  4. The joint between the wall opening and windows shall be continuously filled with glass fiber insulation and the exterior cover trim shall be continuously caulked to seal the joint.

Replace door(s)

For residential buildings located in a CNEL noise boundary, all exterior replacement door(s) must comply with the standards summarized in the table below. Click on each "CNEL Noise Boundary" hyperlink to review the complete text of the prescriptive standards.

CNEL Noise Boundary Prescriptive Standards Established by LACBCM for Mitigation of Interior Noise Levels When Exterior Door(s) Are Replaced
65 dB < 70 dB
  1. Hollow core or lightweight doors and doors with glazed openings shall be replaced with doors that have a minimum laboratory sound transmission class rating of at least STC 35 dB.
  2. Solid core or heavy panel doors shall be fitted with a drop seal at the sill and vinyl bulb seals at the jambs and head.
70 dB < 75 dB
  1. Exterior hinged doors to rooms that are exposed to aircraft noise shall be replaced with a door and seals that have a laboratory sound transmission class rating of at least STC 40 db. A new rabbeted frame shall be provided for each new door to replace the existing frame.
  2. Access doors from a garage to a room within a dwelling shall be replaced with a door and seals that have laboratory sound transmissions rating of at least STC 30 db.
  3. Sliding glass doors to rooms that are exposed to aircraft noise shall be fitted with a secondary sliding glass door installed on the exterior of the existing door and trimmed on all exposed sides with wood trim that is at least 2-inches thick (nominal).
  4. The joint between the wall opening and the new doorframe required in Item No. 3 a, b or c above shall be continuously filled with glass fiber insulation and the exterior cover trim shall be continuously caulked to seal the joint.
75 dB +
  1. Exterior hinged doors to rooms shall be replaced with a door and seals that have a laboratory sound transmission class rating of at least STC 40 db. A new rabbeted frame shall be provided for each new door to replace the existing frame.
  2. Access doors from a garage to a room within a dwelling shall be replaced with a door and seals that have a laboratory sound transmission rating of at least STC 30 dB.
  3. Exterior sliding glass doors in rooms shall be fitted with a secondary sliding glass door installed on the exterior of the existing door and trimmed on all exposed sides with wood trim that is at least 2 inches thick (nominal).
  4. The joint between the wall opening and the new door frame required in Item No. 3 a, b or c above shall be continuously filled with glass fiber insulation and the exterior cover trim shall be continuously caulked to seal the joint.

Replaced damaged wood framing

For residential buildings located in a CNEL noise boundary, the damaged wood framing repair must comply with the standards summarized in the table below.

CNEL Noise Boundary Prescriptive Standards Established by LACBCM for Mitigation of Interior Noise Levels
65 dB < 70 dB Click on the CNEL Noise Boundary for your building or structure to review the detailed prescriptive standards for floors, exterior walls, and roofs.
70 dB < 75 dB
75 dB +

Chimney repair

For residential buildings located in a CNEL noise boundary, the chimney repair must comply with the standards summarized in the table below. Click on each "CNEL Noise Boundary" hyperlink to review the complete text of the prescriptive standards.

CNEL Noise Boundary Prescriptive Standards Established by LACBCM for Mitigation of Interior Noise Levels When a Chimney is Repaired
65 dB < 70 dB Each fireplace constructed of a masonry unit shall be fitted with a damper at the top of the chimney that is operated from the firebox and shall have glass doors across the front of the firebox.
70 dB < 75 dB
75 dB +