Dryer exhaust systems shall be independent of all other systems and shall convey the moisture to the outdoors.
Exception: This section shall not apply to listed and labeled condensing (ductless) clothes dryers.
|DRYER EXHAUST DUCT FITTING TYPE||EQUIVALENT LENGTH|
|4 inch radius mitered 45 degree elbow||2 feet 6 inches|
|4 inch radius mitered 90 degree elbow||5 feet|
|6 inch radius smooth 45 degree elbow||1 foot|
|6 inch radius smooth 90 degree elbow||1 foot 9 inches|
|8 inch radius smooth 45 degree elbow||1 foot|
|8 inch radius smooth 90 degree elbow||1 foot 7 inches|
|10 inch radius smooth 45 degree elbow||9 inches|
|10 inch radius smooth 90 degree elbow||1 foot 6 inches|
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 degree = 0.0175 rad.
Where space for a clothes dryer is provided, an exhaust duct system shall be installed. Where the clothes dryer is not installed at the time of occupancy the exhaust duct shall be capped or plugged in the space in which it originates and identified and marked "future use."
Exception: Where a listed condensing clothes dryer is installed prior to occupancy of the structure.
Range hoods shall discharge to the outdoors through a single-wall duct. The duct serving the hood shall have a smooth interior surface, shall be air tight and shall be equipped with a backdraft damper. Ducts serving range hoods shall not terminate in an attic or crawl space or areas inside the building.
Exception: Where installed in accordance with the manufacturer's installation instructions, and where mechanical or natural ventilation is otherwise provided, listed and labeled ductless range hoods shall not be required to discharge to the outdoors.
Single-wall ducts serving range hoods shall be constructed of galvanized steel, stainless steel or copper.
Exception: Ducts for domestic kitchen cooking appliances equipped with down-draft exhaust systems shall be permitted to be constructed of schedule 40 PVC pipe and fittings provided that the installation complies with all of the following:
- The duct is installed under a concrete slab poured on grade; and
- The underfloor trench in which the duct is installed is completely backfilled with sand or gravel; and
- The PVC duct extends not more than 1 inch (25 mm) above the indoor concrete floor surface; and
- The PVC duct extends not more than 1 inch (25 mm) above gradeoutside of the building; and
- The PVC ducts are solvent cemented.
|AREA TO BE VENTILATED||VENTILATION RATES|
|Kitchens||100 cfm intermittent or
25 cfm continuous
|Bathrooms—Toilet Rooms||Mechanical exhaust capacity of
50 cfm intermittent or 20 cfm continuous
For SI: 1 cubic foot per minute = 0.4719 L/s.