Adopting Agency BSC SFM. Adopt Entire Chapter Adopt Entire Chapter as amended (amended sections listed below) X X X X X X X X X X

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1 Adopting Agency BSC SFM Adopt Entire Chapter Adopt Entire Chapter as amended (amended sections listed below) Adopt only those sections that are listed below CALIFORNIA MECHANICAL CODE MATRIX ADOPTION TABLE CHAPTER 6 DUCT SYSTEMS HCD DSA OSHPD 1 2 1/AC AC SS SS/CC X X X X X X X X X X Article/Section 601.2, Exception X X X X X X X X X X X X X X X X X X X X X X 602.1, Exception X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X CA DPH 2010 CALIFORNIA MECHANICAL CODE 103

2 CALIFORNIA MECHANICAL CODE

3 CHAPTER 6 DUCT SYSTEMS Scope Ducts and plenums that are portions of a heating, cooling, absorption or evaporative cooling, or productconveying system shall comply with the requirements of this chapter Sizing Requirements. Duct systems used with blowertype equipment that are portions of a heating, cooling, absorption, evaporative cooling, or outdoor-air ventilation system shall be sized in accordance with Chapter 17, or by other approved methods. Exception: [HCD 1 & HCD 2] Duct sizing calculations are not required for existing duct systems The performance criteria and requirements herein contemplate a duct that is a structural assembly having the capacity to support occupant health and safety while minimizing its own contribution to property damage under emergency conditions. Ducts can supply fresh or treated air in support of life and health, can convey products of combustion away from a fire zone, can maintain a pressure differential that facilitates evacuation and reduces the spread of fire and smoke, and can facilitate firefighter access to a fire source Material General. Supply air, return air, and outside air for heating, cooling, or evaporative cooling systems shall be conducted through duct systems constructed of metal as set forth in the ANSI/SMACNA HVAC Duct Construction Standards - Metal and Flexible, or another approved duct construction standard. Rectangular ducts in excess of two (2) inches w.g. shall comply with the ANSI/SMACNA HVAC Duct Construction Standards - Metal and Flexible, or another approved duct construction standard. Ducts, plenums, and fittings may be constructed of concrete, clay, or ceramics when installed in the ground or in a concrete slab, provided the joints are tightly sealed. In other than Group A, E, H, I, L, and R occupancies, high-rise buildings, and other applications listed in Section regulated by the Office of the State Fire Marshal, corridors shall not be used to convey air to or from rooms if the corridor is required be of fire-resistive construction per the Building Code. In Group A, E, H, I, L, and R occupancies, high-rise buildings, and other applications listed in Section regulated by the Office of the State Fire Marshal, corridors shall not be used to convey air to or from rooms except where permitted in accordance with Section of the California Building Code. Exception: [OSHPD 1, 2, 3 & 4] (See Section ). Not permitted for [OSHPD 1, 2, 3 & 4] Concealed building spaces or independent construction within buildings may be used as ducts or plenums. When gypsum products are exposed in ducts or plenums, the air temperature shall be restricted to a range from 50 F (10 C) to 125 F (52 C), and moisture content shall be controlled so that the material is not adversely affected. For the purpose of this section, gypsum products shall not be exposed in ducts serving as supply from evaporative coolers, and in other air-handling systems regulated by this chapter when the temperature of the gypsum product will be below the dew point temperature. See Chapter 8 for limitations on combustion products venting systems extending into or through ducts or plenums. See Chapter 5 for limitations on environmental air systems exhaust ducts extending into or through ducts or plenums. Exhaust ducts under positive pressure and venting systems shall not extend into or pass through ducts or plenums. For appliance vents and chimneys, see Chapter Combustibles Within Ducts or Plenums. Materials exposed within ducts or plenums shall be noncombustible or shall have a flame spread index not greater than twenty-five (25) and a smoke developed index not greater than fifty (50), when tested as a composite product in accordance with one of the following test methods: NFPA 255, Method of Test of Surface Burning Characteristics of Building Materials, ASTM E 84, Surface Burning Characteristics of Building Materials, or UL 723, Test for Surface Burning Characteristics of Building Materials, except as indicated below. Exceptions: (1) Return-air and outside-air ducts, plenums, or concealed spaces that serve a dwelling unit shall be permitted to be of combustible construction. (2) Air filters meeting the requirements of Sections and (3) Water evaporation media in an evaporative cooler. (4) Charcoal filters when protected with an approved fire suppression system. (5) Electrical wiring in plenums shall comply with NFPA 70, National Electrical Code. Electrical wires and cables and optical fiber cables shall be listed and labeled as suitable for use in plenums and shall have a flame spread distance not greater than five (5) feet (1,524 mm), an average optical density not greater than 0.15, and a peak optical density not greater than 0.5, when tested in accordance with NFPA 262, Flame Travel and Smoke of Wires and Cables for Use in Air-Handling Spaces. (6) Nonmetallic fire sprinkler piping in plenums shall be listed and labeled as suitable for use in plenums and shall have a flame spread distance not greater than five (5) feet (1,524 mm), an average optical density not greater than 0.15 and, a peak optical density not greater than 0.5, when tested in accordance with UL 1887, Fire Test of Plastic Sprinkler Pipe for Visible Flame and Smoke Characteristics CALIFORNIA MECHANICAL CODE 105

4 (7) Nonmetallic pneumatic tubing in plenums shall be listed and labeled as suitable for use in plenums and shall have a flame spread distance not greater than five (5) feet (1,524 mm), an average optical density not greater than 0.15, and a peak optical density not greater than 0.5, when tested in accordance with UL 1820, Fire Test of Pneumatic Tubing for Flame and Smoke Characteristics. (8) Loudspeakers and recessed lighting fixtures, including their assemblies and accessories, in plenums shall be listed and labeled as suitable for use in plenums and shall have a peak rate of heat release not greater than 100 kilowatts, an average optical density not greater than 0.15, and a peak optical density not greater than 0.5, when tested in accordance with UL 2043, Fire Test for Heat and Visible Smoke Release for Discrete Products and their Accessories Installed in Air-Handling Spaces. (9) Smoke detectors. (10) Duct insulation, coverings, and linings and other supplementary materials complying with Section (11) Materials in a Group H, Division 6, fabrication area including the areas above and below the fabrication area sharing a common air recirculation path with the fabrication area Factory-Made Air Ducts. Factory-made air ducts shall be approved for the use intended or shall conform to the requirements of the referenced standard for air ducts in Chapter 17. Each portion of a factory-made air duct system shall be identified by the manufacturer with a label or other suitable identification indicating compliance with the referenced standard for air ducts in Chapter 17 and its class designation. These ducts shall be listed and shall be installed in accordance with the terms of their listing. Flexible air connectors are not permitted Flexible Ducts. [OSHPD 1, 2, 3 & 4] In hospital building projects and all other health-care facilities, including clinics and correctional treatment centers, flexible ducts of not more than 10 feet (3048 mm) in length may be used to connect supply, return or exhaust-air terminal devices to rigid duct systems. Where constant volume, variable volume or mixing boxes are utilized, flexible duct of not more than 10 feet (3048 mm), may be used on the inlet side for alignment. An internal impervious liner shall be provided to isolate insulation material from conditioned air Joints and Seams of Ducts. Joints of duct systems shall be made substantially air-tight by means of tapes, mastics, gasketing, or other means. Crimp joints for round ducts shall have a contact lap of at least inch (38 mm) and shall be mechanically fastened by means of at least three (3) sheet-metal screws equally spaced around the joint, or an equivalent fastening method. Joints and seams for inch (0.41 mm) (No. 28 gauge) and inch (0.33 mm) (No. 30 gauge) residential rectangular ducts shall be as specified in the ANSI/SMACNA HVAC Duct Construction Standards - Metal and Flexible or another approved duct construction standard for inch (0.48 mm) (No. 26 gauge) material. Joints and seams for rectangular duct systems shall be as specified in the ANSI/SMACNA HVAC Duct Construction Standards - Metal and Flexible or another approved duct construction standard. Joints and seams for flat oval ducts and round ducts in other than single-dwelling units shall be as specified in the ANSI/SMACNA HVAC Duct Construction Standards - Metal and Flexible or another approved duct construction standard. Joints and seams and all reinforcements for factory-made air ducts and plenums shall meet with the conditions of prior approval in accordance with the installation instructions that shall accompany the product. Closure systems for rigid air ducts and plenums shall be listed in accordance with UL 181A, Standard for Closure Systems for Use with Rigid Air Ducts and Air Connectors. Closure systems for flexible air ducts shall be listed in accordance with UL 181B, Standard for Closure Systems for Use with Flexible Air Ducts and Air Connectors Metal. Every duct, plenum, or fitting of metal shall comply with the ANSI/SMACNA HVAC Duct Construction Standards - Metal and Flexible or duct systems complying with UL 181 for Factory Made Air Ducts and Air Connectors Tin. Existing tin ducts may be used when cooling coils are added to a heating system, provided the first ten (10) feet (3,048 mm) of the duct or plenum measured from the cooling coil discharge are constructed of metal of the gauge thickness set forth in the ANSI/SMACNA HVAC Duct Construction Standards - Metal and Flexible or another approved duct construction standard or are of approved material and construction. Tin ducts completely enclosed in inaccessible concealed areas need not be replaced. All accessible ducts shall be insulated to comply with the ANSI/SMACNA HVAC Duct Construction Standards - Metal and Flexible or another approved duct construction standard. For the purpose of this subsection, ducts shall be considered accessible where the access space is thirty (30) inches (762 mm) or greater in height Vibration Isolators. Vibration isolators installed between mechanical equipment and metal ducts (or casings) shall be made of an approved material and shall not exceed ten (10) inches (254 mm) in length Quality of Material. Galvanized steel shall be of lockforming quality with a minimum coating of 1.25 ounces of zinc per square foot (0.04 kg/m 3 ) conforming to the requirements of ASTM A653/A653M-07 Standard Specification for Steel Sheet, Zinc-Coat (Galvanized) or Zinc-Iron Alloy-Coat (Galvannealed) by the Hot Dip Process Installation of Ducts General Ducts Under Floor or Crawl Space. Air ducts installed under a floor in a crawl space shall be installed as follows: CALIFORNIA MECHANICAL CODE

5 (1) Shall not prevent access to any area of the crawl space. (2) Where it is required to move under ducts for access to areas of the crawl space a minimum vertical clearance of eighteen (18) inches (457 mm) shall be provided Metal Ducts. Ducts shall be securely fastened in place at each change of direction and as set forth in the ANSI/SMACNA HVAC Duct Construction Standards - Metal and Flexible or another approved duct construction standard. Vertical rectangular ducts and vertical round ducts shall be supported as set forth in the ANSI/SMACNA HVAC Duct Construction Standards - Metal and Flexible or another approved duct construction standard. Riser ducts shall be held in place by means of metal straps or angles and channels to secure the riser to the structure. Metal ducts shall be installed with at least four (4) inches (102 mm) separation from earth. Metal ducts when installed in or under a concrete slab shall be encased in at least two (2) inches (51 mm) of concrete. Ducts shall be installed in a building with adequate clearance so as to permit retaining the full thickness of fireproofing on structural members. Supports for rectangular ducts as set forth in the ANSI/SMACNA HVAC Duct Construction Standards - Metal and Flexible or another approved duct construction standard, when suspended from above, shall be installed on two opposite sides of each duct and shall be riveted, bolted, or metal screwed to each side of the duct at not more than the intervals specified. Horizontal round ducts forty (40) inches (1,016 mm) or less in diameter, when suspended from above shall be supported at intervals not more than as set forth in the ANSI/SMACNA HVAC Duct Construction Standards - Metal and Flexible or another approved duct construction standard with one hanger installed to comply with the requirements listed below: Ducts shall be equipped with tight-fitting circular bands extending around the entire perimeter of the duct at each specified support interval Circular bands shall be not less than one (1) inch (25 mm) wide nor less than equivalent to the gauge of the duct material it supports. Exception: Ducts ten (10) inches (254 mm) and less in diameter may be supported by No. 18 gauge galvanized steel wire Each circular band shall be provided with a suitable means of connecting to the suspending support Ducts shall be braced and guyed to prevent lateral or horizontal swing Factory-Made Air Ducts. Listed Class 0 or Class 1 factory-made air ducts may be installed in any occupancy covered by this code. Factory-made air ducts shall not be used for vertical risers in air-duct systems serving more than two stories. Such ducts shall not penetrate construction where fire dampers are required. Factory-made air ducts shall be installed with at least four (4) inches (102 mm) of separation from earth, except when installed as a liner inside of concrete, tile, or metal pipe; they shall be protected from physical damage. The temperature of the air to be conveyed in any of these classes of ducts shall not exceed 250 F (122 C) Protection of Ducts. Ducts installed in locations where they are exposed to mechanical damage by vehicles or from other causes shall be protected by approved barriers Support of Ducts. Installers shall provide the manufacturer s field fabrication and installation instructions. In the absence of specific supporting materials and spacing, approved factory-made air ducts may be installed as set forth in the ANSI/SMACNA HVAC Duct Construction Standards - Metal and Flexible or another approved duct construction standard Protection Against Flood Damage. In flood hazard areas, ducts shall be located above the design flood elevation or shall be designed and constructed to prevent water from entering or accumulating within the ducts during floods up to the design flood elevation. If the ducts are located below the design flood elevation, the ducts shall be capable of resisting hydrostatic and hydrodynamic loads and stresses, including the effects of buoyancy, during the occurrence of flooding to the design flood elevation Insulation of Ducts. Supply-, return-air ducts and plenums of a heating or cooling system shall be insulated to achieve the minimum thermal (R) value as set forth in Tables 6-6A and B. [OSHPD 1, 2, 3 & 4] Cold air ducts shall be insulated wherever necessary or to prevent condensation problems. Exceptions: (1) Factory-installed plenums, casings, or ductwork furnished as a part of HVAC equipment tested and rated in accordance with approved energy efficiency standards. (2) Ducts or plenums located in conditioned spaces. (3) For runouts less than ten (10) feet (3,048 mm) in length to air terminals or air outlets, the rated R value of insulation need not exceed R-3.5 (R-0.6). (4) Backs of air outlets and outlet plenums exposed to unconditioned or indirectly conditioned spaces with face areas exceeding five (5) square feet (0.5 m ) need not exceed R-2 (R-0.4); those five (5) square feet (0.5 m 2 ) or smaller need not be insulated. 5) Ducts and plenums used exclusively for evaporative cooling systems. Approved materials shall be installed within ducts and plenums for insulating, sound deadening, or other purposes. Materials shall have a mold, humidity, and erosion-resistant surface that meets the requirements of the referenced standard for air ducts in Chapter 17. Duct liners in systems operating with air velocities exceeding 2,000 feet per minute (10.16 m/s) shall be fastened with both adhesive and mechanical fasteners, and exposed edges shall have adequate treatment to withstand the operating velocity CALIFORNIA MECHANICAL CODE 107

6 Insulation applied to the surface of ducts, including duct coverings, linings, tapes, and adhesives, located in buildings shall have a flame-spread index not greater than twenty-five (25) and a smoke developed index not greater than fifty (50), when tested in accordance with NFPA 255, Method of Test of Burning Characteristics of Building Materials, or in accordance with ASTM E 84, Surface Burning Characteristics of Building Materials, or in accordance with the provisions of UL 723, Test for Surface Burning Characteristics of Building Materials. The specimen preparation and mounting procedures of ASTM E 2231, Specimen Preparation and Mounting of Pipe and Duct Insulation Materials to Assess Surface Burning Characteristics, shall be used. Air duct coverings and linings shall not flame, glow, smolder, or smoke when tested in accordance with ASTM C 411, Hot-Surface Performance of High-Temperature Thermal Insulation, at the temperature to which they are exposed in service. In no case shall the test temperature be below 250 F (121 C). Factory-made air ducts and faced insulations intended for installation on the exterior of ducts shall be legibly printed with the name of the manufacturer, the thermal resistance (R) value at installed thickness, and the flame-spread index and smoke developed index of the composite material [OSHPD 1, 2, 3 (surgical clinics) & 4] Thermal acoustical lining materials shall not be installed within ducts, terminal boxes, sound traps, and other in-duct systems serving areas such as operating, cesarean operating rooms, delivery rooms, post anesthesia care units, cystoscopy, cardiac cath labs, nurseries, intensive care units, newborn intensive care units, and airborne infection Isolation rooms unless terminal filters with 90 percent average efficiency based on ASHRAE Standard or minimum efficiency rating value (MERV) of 14 are installed downstream of the duct lining [OSHPD 1, 2 & 4] Thermal or acoustical lining materials shall not be installed within ducts which are downstream of the percent high-efficiency particulate air (HEPA) filter or with minimum efficiency rating value (MERV) of 17 required in Section for protective environment rooms Smoke Dampers, Fire Dampers, and Ceiling Dampers Smoke Dampers. Smoke dampers shall comply with the standards for leakage-rated dampers referenced in Chapter 17, and shall be installed in accordance with approved manufacturer s installation instructions when required by the Building Code. Smoke dampers shall be labeled by an approved agency Fire Dampers. Fire dampers shall comply with the standard for fire dampers referenced in Chapter 17, and shall be installed in accordance with the approved manufacturer s installation instructions when required by the Building Code. Fire dampers shall have been tested for closure under airflow conditions and shall be labeled for both maximum airflow permitted and direction of flow. When more than one damper is installed at a point in a single air path, the entire airflow shall be assumed to be passing through the smallest damper area. Fire dampers shall be labeled by an approved agency. Ductwork shall be connected to damper sleeves or assemblies in accordance with the fire damper manufacturer s installation instructions Ceiling Radiation Dampers. Ceiling radiation dampers shall comply with the standard for ceiling radiation dampers referenced in Chapter 17, and shall be installed in accordance with the manufacturer s approved installation instructions in the fire-resistive ceiling element of floor-ceiling and roofceiling assemblies when required by the Building Code. Fire dampers not meeting the temperature limitation of ceiling radiation dampers shall not be used as a substitute. Ceiling radiation dampers shall be labeled by an approved agency Multiple Arrangements. When size requires the use of multiple dampers, the installation shall be framed in an approved manner to ensure that the dampers remain in place Access and Identification. Dampers shall be provided with an approved means of access large enough to permit inspection and maintenance of the damper and its operating parts. The access shall not impair fire-resistive construction. Access shall not require the use of tools, keys, or special knowledge. Access points shall be permanently identified on the exterior by a label with letters not less than 1 2 inch (12.7 mm) in height reading: SMOKE DAMPER or FIRE DAMPER. Access doors in ducts shall be tight fitting and suitable for the required duct construction Freedom from Interference. Dampers shall be installed in a manner to ensure positive closing or opening as required by function. Interior liners or insulation shall be held back from portions of a damper, its sleeve, or adjoining duct that would interfere with the damper s proper operation. Exterior materials shall be installed so as to avoid interference with the operation or maintenance of external operating devices needed for proper function Temperature Classification of Operating Elements. Fusible links, thermal sensors, and pneumatic or electric operators shall have a temperature rating or classification as required by the Building Code When the automatic activation of a smoke damper or a combination smoke-fire damper occurs, the HVAC system serving such dampers shall immediately shut down. Exceptions: (1) HVAC systems that are part of an engineered smoke evacuation system. (2) Where the automatic activation causes all the smoke dampers and combination smoke-fire dampers to close in the enclosed space having a common atmosphere where openings are required to be protected. (3) Where analysis demonstrates shutoff would create a greater hazard. The HVAC system shall not be restarted again until all the dampers are reset and fully opened Ventilating Ceilings General. Perforated ceilings may be used for air supply within the limitations of this section. Exit corridors, when required to be of fire-resistive construction by the Building Code, shall not have ventilating ceilings CALIFORNIA MECHANICAL CODE

7 [OSHPD 1, 2, 3 & 4] Ventilating ceilings are not permitted in health facilities Requirements. Ventilating ceilings shall comply with the following provisions: Suspended ventilating ceiling material shall have a Class I flame-spread classification on both sides, determined in accordance with the Building Code. Suspended ventilating ceiling supports shall be of noncombustible materials Lighting fixtures recessed into ventilating ceilings shall be of a type approved for that purpose Use of Under-Floor Space as Supply Plenum for Dwelling Units. An under-floor space may be used as a supply plenum, provided: The use of under-floor space shall be limited to dwelling units not more than two stories in height. Except for the floor immediately above the under-floor plenum, supply ducts shall be provided extending from the plenum to registers on other floor levels. Exception: In flood hazard areas, under-floor spaces shall not be used as supply plenums unless the flood opening requirements in the Building Code are satisfied Such spaces shall be cleaned of all loose combustible scrap material and shall be tightly and substantially enclosed The enclosing material of the under-floor space, including the sidewall insulation, shall be not more flammable than one (1) inch (25 mm) (nominal) wood boards (flame-spread index of 200). Installation of foam plastics is regulated by the Building Code Access shall be through an opening in the floor and shall be not less than twenty-four (24) inches by twenty-four (24) inches (610 mm x 610 mm) A furnace supplying warm air to under-floor space shall be equipped with an automatic control that will start the aircirculating fan when the air in the furnace bonnet reaches a temperature not higher than 150 F (66 C). Such control shall be one that cannot be set higher than 150 F (66 C) A furnace supplying warm air to such space shall be equipped with an approved temperature limit control that will limit outlet air temperature to 200 F (93 C) A noncombustible receptacle shall be placed below each floor opening into the air chamber, and such receptacle shall conform to the following: The receptacle shall be securely suspended from the floor members and shall be not more than eighteen (18) inches (457 mm) below the floor opening The area of the receptacle shall extend three (3) inches (76 mm) beyond the opening on all sides The perimeter of the receptacle shall have a vertical lip at least one (1) inch (25.4 mm) high at the open sides if it is at the level of the bottom of the joists, or three (3) inches (76 mm) high if the receptacle is suspended Floor registers shall be designed for easy removal in order to give access for cleaning the receptacles Exterior walls and interior stud partitions shall be firestopped at the floor Each wall register shall be connected to the air chamber by a register box or boot A duct conforming with Section shall extend from the furnace supply outlet at least six (6) inches (152 mm) below combustible framing The entire ground surface of the under-floor space shall be covered with a vapor barrier having a minimum thickness of four (4) mils ( mm) and a flame-spread index of 200 or less Fuel-gas lines and plumbing waste cleanouts are not located within the space Automatic Shutoffs. Air-moving systems supplying air in excess of 2000 cubic feet per minute (944 L/s) to enclosed spaces within buildings shall be equipped with an automatic shutoff. Automatic shutoff shall be accomplished by interrupting the power source of the airmoving equipment upon detection of smoke in the main supplyair duct served by such equipment. Smoke detectors shall be labeled by an approved agency, approved and listed by California State Fire Marshal for air duct installation and shall be installed in accordance with the manufacturer s approved installation instructions. Such devices shall be compatible, with the operating velocities, pressures, temperatures, and humidities of the system. Where fire detection or alarm systems are provided for the building, the smoke detectors required by this section shall be supervised by such systems, and installed in accordance with NFPA 72, National Fire Alarm and Signaling, and the California Building and Fire Codes. Exceptions: (1) When the space supplied by the air-moving equipment is served by a total coverage smoke-detection system complying with the California Fire Code, interconnection to such system may be used to accomplish the required shutoff. (2) Automatic shutoff is not required when all occupied rooms served by the air-handling equipment have direct exit to the exterior and the travel distance does not exceed 100 feet (30,480 mm). (3) Automatic shutoff is not required for Group R, Division 3 and Group U Occupancies. (4) Automatic shutoff is not required for approved smokecontrol systems or where analysis demonstrates shutoff would create a greater hazard such as may be encountered in air-moving equipment supplying specialized portions of Group H Occupancies. Such equipment shall be required to have smoke detection with remote indication and manual shutoff capability at an approved location. (5) Smoke detectors that are factory installed in listed airmoving equipment may be used in lieu of smoke detectors installed in the main supply-air duct served by such equipment CALIFORNIA MECHANICAL CODE 109

8 TAbLE 6-6 A (I-P Units) Minimum Duct Insulation R Value a Cooling and Heating Only Supply Ducts and Return Ducts d, e Climate Zone Duct Location Envelope HDD65 CDD50 Exterior Ventilated Unvented Unvented Uncon- Indirectly buried Criteria Table Attic Attic w/ Attic w/ ditioned Conbackloaded Roof Space b ditioned Ceiling Insulation a Space c Heating-Only Ducts 5-1 to ,800 all none none none none none none none 5-8 to ,801 3,600 all R-3.5 none none none none none none 5-13 to ,601 5,400 all R-3.5 none none none none none none 5-16 to ,401 7,200 all R-6 R-3.5 none none none none R to ,201 9,000 all R-6 R-6 R-3.5 none none none R to ,001 10,800 all R-8 R-6 R-6 none R-3.5 none R ,801 12,600 all R-8 R-6 R-6 none R-6 none R ,601 16,200 all R-8 R-8 R-6 none R-6 none R ,201 19,800 all R-10 R-8 R-8 none R-6 none R ,801+ all R-10 R-10 R-8 none R-8 none R-6 Cooling-Only Ducts 5-15, 18, 20, all 0 1,800 R-1.9 R-1.9 R-1.9 R-1.9 R-1.9 none none 22 to , 14, 17, all 1,801 3,600 R-3.5 R-1.9 R-3.5 R-1.9 R-1.9 none none 19, , 9, 11, 13, all 3,601 5,400 R-3.5 R-3.5 R-6 R-1.9 R-1.9 none none , 6, 8, 10 all 5,401 7,200 R-6 R-6 R-6 R-3.5 R-1.9 none none 5-3, 5-5 all 7,201 9,000 R-6 R-6 R-6 R-3.5 R-3.5 none R all 9,001 10,800 R-6 R-6 R-8 R-3.5 R-3.5 none R all 10,801+ R-8 R-8 R-8 R-3.5 R-3.5 none R-3.5 Return Ducts 5-15 to 5-26 all climates R-3.5 R-3.5 R-3.5 none none none none none Notes: a b c d e Insulation R-values, measured in (h ft 2 ºF)/Btu, are for the insulation as installed and do not include film resistance. The required minimum thicknesses do not consider water vapor transmission and possible surface condensation. Where exterior walls are used as plenum walls, wall insulation shall be as required by the most restrictive condition. Insulation resistance measured on a horizontal plane in accordance with ASTM C518 at a mean temperature of 75ºF (24ºC) at the installed thickness. Includes crawl spaces, both ventilated and nonventilated. Includes return-air plenums with or without exposed roofs above. Vapor retarders shall be installed on supply ducts in spaces vented to the outside in geographic areas where the average summer dewpoint temperature based on the 2-1/2 percent column of dry-bulb and mean coincident wet-bulb temperature exceeds 60ºF (16ºC). Insulation shall have an approved weatherproof barrier CALIFORNIA MECHANICAL CODE

9 TAbLE 6-6 b (I-P Units) Minimum Duct Insulation R Value a Combined Heating and Cooling Ducts d, e Climate Zone Duct Location Envelope HDD65 CDD50 Exterior Ventilated Unvented Unvented Uncon- Indirectly buried Criteria Attic Attic w/ Attic w/ Roof ditioned Conditioned Table backloaded Insulation a Space b Space c Ceiling ,801+ R-8 R-6 R-8 R-3.5 R-3.5 none R ,001 10,800 R-6 R-6 R-8 R-3.5 R-3.5 none R ,201 9,000 R-6 R-6 R-6 R-3.5 R-3.5 none R ,200 R-6 R-3.5 R-6 R-3.5 R-1.9 none R ,800 7,201+ R-6 R-6 R-6 R-3.5 R-3.5 none R ,800 5,401 7,200 R-6 R-6 R-6 R-3.5 R-3.5 none R , ,400 R-3.5 R-3.5 R-6 R-1.9 R-1.9 none R ,801 2,700 5,401+ R-6 R-6 R-6 R-3.5 R-3.5 none R ,801 2, ,400 R-6 R-3.5 R-6 R-1.9 R-1.9 none R ,701 3,600 5,401+ R-6 R-6 R-6 R-3.5 R-3.5 none R ,701 3,600 3,601 5,400 R-6 R-6 R-6 R-3.5 R-3.5 none R ,701 3, ,600 R-3.5 R-3.5 R-3.5 R-1.9 R-1.9 none R ,601 5,400 3,601+ R-6 R-6 R-6 R-3.5 R-3.5 none R ,601 5,400 1,801 3,600 R-6 R-3.5 R-6 R-1.9 R-3.5 none R ,601 5, ,800 R-3.5 R-3.5 R-3.5 R-1.9 R-1.9 none R ,401 7,200 3,601+ R-6 R-6 R-6 R-3.5 R-3.5 none R ,401 7,200 1,801 3,600 R-6 R-6 R-6 R-1.9 R-3.5 none R ,401 7, ,800 R-6 R-3.5 R-3.5 R-1.9 R-3.5 none R ,201 9,000 1,801+ R-8 R-6 R-6 R-1.9 R-3.5 none R ,201 9, ,800 R-6 R-6 R-6 R-1.9 R-3.5 none R ,001 10,800 1,801+ R-8 R-6 R-6 R-1.9 R-6 none R ,001 10, ,800 R-8 R-6 R-6 R-1.9 R-3.5 none R ,801 12,600 all R-8 R-6 R-6 R-1.9 R-6 none R ,601 16,200 all R-8 R-8 R-8 R-1.9 R-6 none R ,201 19,800 all R-10 R-8 R-8 R-3.5 R-6 none R ,801+ all R-10 R-10 R-8 R-3.5 R-8 R-3.5 R-6 Notes: a Insulation R-values, measured in (h ft 2 F)/Btu, are for the insulation as installed and do not include film resistance. The required minimum thicknesses do not consider water vapor transmission and possible surface condensation. Where exterior walls are used as plenum walls, wall insulation shall be as required by the most restrictive condition. Insulation resistance measured on a horizontal plane in accordance with ASTM C518 at a mean temperature of 75 F (24ºC) at the installed thickness. b Includes crawl spaces, both ventilated and nonventilated. c Includes return air plenums with or without exposed roofs above. d Vapor retarders shall be installed on cooling supply ducts in spaces vented to the outside in geographic areas where the average summer dewpoint temperature based on the 2-1/2 percent column of dry-bulb and mean coincident wet-bulb temperature exceeds 60 F (16 C). e Insulation shall have an approved weatherproof barrier CALIFORNIA MECHANICAL CODE 109.2

10 CALIFORNIA MECHANICAL CODE