Washington Administrative Code › Title 51 - Enterprise Services, Department of (Building Code Council) › Chapter 51-52 - State Building Code adoption and amendment of the 2021 edition of the International Mechanical Code › Section 51-52-0504 - Section 504-Clothes dryer exhaust

Current through Register Vol. 24-14, July 15, 2024
504.4 Exhaust installation.
Dryer exhaust ducts
				for clothes dryers shall terminate on the outside of the building and shall be
				equipped with a backdraft damper located where the duct terminates. Dryer
				exhaust ducts may terminate at exterior wall louvers with openings spaced not
				less than 1/2-inch in any direction.
Screens shall not be installed at the duct termination. Ducts
				shall not be connected or installed with sheet metal screws or other fasteners
				that will obstruct the exhaust flow. Clothes dryer exhaust ducts shall not be
				connected to a vent connector, vent or chimney. Clothes dryer exhaust ducts
				shall not extend into or through ducts or plenums.
Domestic dryer exhaust ducts may terminate at a common location
				where each duct has an independent back-draft damper.
504.11 Common exhaust systems for clothes dryers located
				in multistory structures.
Where a common multistory duct system is
				designed and installed to convey exhaust from multiple clothes dryers, the
				construction of the system shall be in accordance with all of the
				following:
1. The shaft in which the
			 duct is installed shall be constructed and fire-resistance rated as required by
			 the
International Building Code
.
2. Dampers shall be prohibited in the exhaust
			 duct. Penetrations of the shaft and ductwork shall be protected in accordance
			 with Section 607.5.5, Exception 2.
3. Rigid metal ductwork shall be installed
			 within the shaft to convey the exhaust. The ductwork shall be constructed of
			 sheet steel having a minimum thickness of 0.0187 inch (0.4712 mm) (No. 26 gage)
			 and in accordance with SMACNA
Duct Construction
			 Standards
.
4. The ductwork
			 within the shaft shall be designed and installed without offsets.
5. The exhaust fan motor design shall be in
			 accordance with Section 503.2.
6.
			 The exhaust fan motor shall be located outside of the air-stream.
7. The exhaust fan shall run continuously,
			 and shall be connected to a standby power source.
8. Exhaust fan operation shall be monitored
			 in an
approved
location and shall initiate an audible or
			 visual signal when the fan is not in operation.
9. Makeup air shall be provided for the
			 exhaust system to maintain the minimum flow for the exhaust fan when the dryers
			 are not operating. Additionally, makeup air shall be provided when required by
			 Section 504.7.
10. A cleanout
			 opening shall be located at the base of the shaft to provide
access
to the duct to allow for cleaning and inspection. The
			 finished opening shall be not less than 12 inches by 12 inches (305 mm by 305
			 mm).
11. Screens shall not be
			 installed at the termination.
12.
			 The common multistory duct system shall serve only clothes dryers and shall be
			 independent of other exhaust systems.
Statutory Authority:
				  RCW
				    19.27.031,
				  19.27.074 and
				  chapters
				  19.27 and
				  34.05 RCW. 13-04-053, §
				  51-52-0504, filed 2/1/13, effective 7/1/13. Statutory Authority:
				  RCW
				    19.27.190,
				  19.27.074,
				  19.27.031 and
				  chapters
				  19.27 and
				  34.05 RCW. 10-03-099, §
				  51-52-0504, filed 1/20/10, effective 7/1/10. Statutory Authority:
				  RCW
				    19.27.190,
				  19.27.020, and
				  chapters
				  19.27 and
				  34.05 RCW. 07-01-092, §
				  51-52-0504, filed 12/19/06, effective
				  7/1/07.