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CITY OF PALM DESERT
Building & Safety Department
73-510 Fred Waring, Palm Desert, CA (760) 776-6420
DOMESTIC CLOTHES DRYER VENTING
2016 California Mechanical Code (CMC), Section 504.4
504.4. Clothes Dryer. A clothes dryer exhaust duct shall not be connected to a vent connector, gas vent, chimney,
and shall not terminate into a crawl space, attic, or other concealed space. Exhaust ducts shall not be assembled
with screws or fastening means that extend into the duct and that are capable of catching lint, and that reduce
energy efficiency of the exhaust system. Exhaust ducts shall be constructed of rigid metallic material.
• Transition ducts used to connect to the dryer to the exhaust duct shall be listed for that application or installed
in accordance with the clothes dryer manufacturer's installation instructions.
• Clothes dryer exhaust ducts shall terminate to the outside of the building in accordance with Section
502.2.1 And shall be equipped with a backdraft damper. Screens shall not be installed at the duct termination.
• Devices, such as fire or smoke dampers, that will obstruct the flow of the exhaust shall not be used. Where
joining of ducts, the crimped end (male) shall be used in the direction of flow.
• Type 1 Clothes Dryer. Primarily used in family living environment. May or may not be coin-operated for public
use.
504.4.1 Provisions for make-up air. Make-up air shall be provided in accordance with the following:
• Make up air shall be provided for Type 1 clothes dryers in accordance with the manufacturer's instructions.
Where a closet is designed for the installation of a clothes dryer, an opening not less than 100 square inches
for make-up air shall be provided in the door or by other approved means.
• Provisions for make-up air shall be provided for Type 2 clothes dryer, with a free area of not less than 1 square
inch for each British thermal unit (Btu/h) total input rating of the dryer(s) installed.
504.4.2. Domestic Clothes Dryer. When a compartment or space is provided for a Type 1, a minimum 4-inch
diameter (102mm) and not less than .016 of an inch thickness the exhaust duct shall have approved material and
installed in accordance Section 504.0.
• Unless otherwise permitted or required by the dryer manufacturer's instructions and approved by the Authority
Having Jurisdiction, domestic dryer moisture exhaust duct shall not exceed a combined horizontal and vertical
length of 14 feet, including two 90 degree elbows. A length of 2 feet shall be reduced for each 90 degree elbow
in excess of two.
504.2.2. Transition Ducts. Listed clothes dryer transition ducts not more than 6 feet in length shall be permitted to
be used to connect the Type 1 dryer to the exhaust ducts. Transition ducts and flexible clothes dryer transition
ducts shall not be concealed within construction, and shall be installed in accordance with the manufacturer's
installation instructions.
4/19/2017