Bathroom and dryer vent duct material

[mtCDCcb]

We are replacing the bathroom and dryer vent ducts in our condo. Both bathrooms and the dryer vent separately. I was wondering what kind of material for this ducting. Can vinyl vent ducting be used for the bathrooms and the dryer. What about flexible aluminum. Where in the building code is this addressed? Thanks

[Jerry Peck - Codeman]

Can vinyl vent ducting be used for the bathrooms and the dryer. What about flexible aluminum. Where in the building code is this addressed? Thanks

Below are the requirements for the exhaust ducts:
SECTION 501 GENERAL
- 501.1 Scope.
- - This chapter shall govern the design, construction and installation of mechanical exhaust systems, including exhaust systems serving clothes dryers and cooking appliances; hazardous exhaust systems; dust, stock and refuse conveyor systems; subslab soil exhaust systems; smoke control systems; energy recovery ventilation systems and other systems specified in Section 502.
- 501.2 Exhaust discharge.
- - The air removed by every mechanical exhaust system shall be discharged outdoors at a point where it will not cause a nuisance and not less than the distances specified in Section 501.2.1. The air shall be discharged to a location from which it cannot again be readily drawn in by a ventilating system. Air shall not be exhausted into an attic or crawl space.
- - - Exceptions:
- - - - 1. Whole-house ventilation-type attic fans shall be permitted to discharge into the attic space of dwelling units having private attics.
- - - - 2. Commercial cooking recirculating systems.
- - 501.2.1 Location of exhaust outlets.
- - - The termination point of exhaust outlets and ducts discharging to the outdoors shall be located with the following minimum distances:
- - - - 1. For ducts conveying explosive or flammable vapors, fumes or dusts: 30 feet (9144 mm) from property lines; 10 feet (3048 mm) from operable openings into buildings; 6 feet (1829 mm) from exterior walls and roofs; 30 feet (9144 mm) from combustible walls and operable openings into buildings which are in the direction of the exhaust discharge; 10 feet (3048 mm) above adjoining grade.
- - - - 2. For other product-conveying outlets: 10 feet (3048 mm) from the property lines; 3 feet (914 mm) from exterior walls and roofs; 10 feet (3048 mm) from operable openings into buildings; 10 feet (3048 mm) above adjoining grade.
- - - - 3. For all environmental air exhaust: 3 feet (914 mm) from property lines; 3 feet (914 mm) from operable openings into buildings for all occupancies other than Group U, and 10 feet (3048 mm) from mechanical air intakes. Such exhaust shall not be considered hazardous or noxious.
- - - - 4. Exhaust outlets serving structures in flood hazard areas shall be installed at or above the elevation required by Section 1612.4 of the Florida Building Code, Building for utilities and attendant equipment.
- - - - 5. For specific systems see the following sections:
- - - - - 5.1. Clothes dryer exhaust, Section 504.4.
- - - - - 5.2. Kitchen hoods and other kitchen exhaust equipment, Sections 506.3.12, 506.4 and 506.5.
- - - - - 5.3. Dust stock and refuse conveying systems, Section 511.2.
- - - - - 5.4. Subslab soil exhaust systems, Section 512.4
- - - - - 5.5. Smoke control systems, Section 513.10.3
- - - - - 5.6. Refrigerant discharge, Section 1105.7
- - - - - 5.7. Machinery room discharge, Section 1105.6.1
- - - 501.2.1.1 Exhaust discharge.
- - - - Exhaust air shall not be directed onto walkways.
- - - 501.2.2 Exhaust opening protection.
- - - - Exhaust openings that terminate outdoors shall be protected with corrosion-resistant screens, louvers or grilles. Openings in screens, louvers and grilles shall be sized not less than 1/4 inch (6 mm) and not larger than 1/2 inch (13 mm). Openings shall be protected against local weather conditions. Louvers that protect exhaust openings in structures located in hurricane-prone regions as defined in the Florida Building Code, Building shall comply with AMCA Standard 550. Outdoor openings located in exterior walls shall meet the provisions for exterior wall opening protectives in accordance with the Florida Building Code, Building.
- 501.3 Pressure equalization.
- - See Section 601.4 of this code and Section 503.2.10.6 of the Florida Building Code, Energy Conservation.
- 501.4 Ducts.
- - Exhaust ducts shall be of metal and such construction shall comply with Chapter 6.

SECTION 504 CLOTHES DRYER EXHAUST
- 504.6 Domestic clothes dryer ducts.
- - Exhaust ducts for domestic clothes dryers shall conform to the requirements of Sections 504.6.1 through 504.6.7.
- - 504.6.1 Material and size.
- - - Exhaust ducts shall have a smooth interior finish and shall be constructed of metal a minimum 0.016 inch (0.4 mm) thick. The exhaust duct size shall be 4 inches (102 mm) nominal in diameter.
- - 504.6.2 Duct installation.
- - - Exhaust ducts shall be supported at 4-foot (1219 mm) intervals and secured in place. The insert end of the duct shall extend into the adjoining duct or fitting in the direction of airflow. Ducts shall not be joined with screws or similar fasteners that protrude into the inside of the duct.
- - 504.6.3 Transition ducts.
- - - Transition ducts used to connect the dryer to the exhaust duct system shall be a single length that is listed and labeled in accordance with UL 2158A. Transition ducts shall be a maximum of 8 feet (2438 mm) in length and shall not be concealed within construction.
- - 504.6.4 Duct length.
- - - The maximum allowable exhaust duct length shall be determined by one of the methods specified in Section 504.6.4.1 or 504.6.4.2.
- - - 504.6.4.1 Specified length.
- - - - The maximum length of the exhaust duct shall be 35 feet (10 668 mm) from the connection to the transition duct from the dryer to the outlet terminal. Where fittings are used, the maximum length of the exhaust duct shall be reduced in accordance with Table 504.6.4.1.
- - - - Exception. Where a clothes dryer booster fan is installed and listed and labeled for the application, the maximum length of the exhaust duct, including any transition duct, shall be permitted to be in accordance with the booster fan manufacturer’s installation instructions. Where a clothes dryer booster fan is installed and not readily accessible from the room in which the dryer is located, a permanent identifying label shall be placed adjacent to where the exhaust duct enters the wall. The label shall bear the words: "This dryer exhaust system is equipped with a remotely located booster fan.”

SECTION 603 DUCT CONSTRUCTION AND INSTALLATION
- 603.4 Metallic ducts.
- - All metallic ducts shall be constructed as specified in the SMACNA HVAC Duct Construction Standards—Metal and Flexible and shall be mechanically attached and sealed using approved closure systems for the pressure class as specified in Table 603.
- - - Exception: Ducts installed within single dwelling units shall have a minimum thickness as specified in Table 603.4.

TABLE 603.4 DUCT CONSTRUCTION MINIMUM SHEET METAL THICKNESSES FOR SINGLE DWELLING UNITS
Round ducts and enclosed rectangular ducts
- 14 inches or less
- - GALVANIZED
- - - Minimum thickness (in.) = 0.0157
- - - Equivalent galvanized gage no. = 28
- - ALUMINUM
- - - Minimum thickness (in.) = 0.0175