Exception: The appliance, equipment and system installations regulated by this code are permitted to be located below the elevation required by Section 1612 of the International Building Code for utilities and attendant equipment provided that they are designed and installed to prevent water from entering or accumulating within the components and to resist hydrostatic and hydrodynamic loads and stresses, including the effects of buoyancy, during the occurrence of flooding to such elevation.
- The appliance is a direct-vent appliance installed in accordance with the conditions of the listing and the manufacturer's instructions.
- Vented room heaters, wall furnaces, vented decorative appliances, vented gas fireplaces, vented gas fireplace heaters and decorative appliances for installation in vented solid fuel-burning fireplaces are installed in rooms that meet the required volume criteria of Section 304.5.
- The appliance is installed in a room or space that opens only into a bedroom or bathroom, and such room or space is used for no other purpose and is provided with a solid weather-stripped door equipped with an approved self-closing device. All combustion air shall be taken directly from the outdoors in accordance with Section 304.6.
- Direct vent appliances.
- Type 1 clothes dryers that are provided with makeup air in accordance with the manufacturer's installation instructions.
- Replacement of a fuel gas utilization appliance that complies with all of the following conditions:
- Replacement appliance has a Btu/hr (kW) input rating not greater than 30 percent above the original appliance input rating.
- Combustion air provisions meet the code requirements in effect at the time of the original installation.
- Replacement appliance shall not cause an existing mechanical system to become unsafe, hazardous, or overloaded.
- Combustion air may be determined using Table 304.1 for gas-fired appliances when combustion air is provided from a single opening from the outdoors, commencing within 12 inches of the bottom of the enclosure.
- Combustion air for power burner appliances equipped with a draft control device and having an input above 400,000 Btu/hr shall have a net free area of 0.2 square inches per 1,000 Btu/hr. Combustion air shall be provided from a single opening from the outdoors, terminating within 12 inches of the bottom of the enclosure. In lieu of this requirement, combustion air requirements specified by the manufacturer for a specific power burner appliance may be approved by the building official.
- Combustion air for power burner appliances not equipped with a draft control device and having an input above 400,000 Btu/hr shall have a net free area of 0.1 square inches per 1,000 Btu/hr. Combustion air shall be provided from a single opening from the outdoors, terminating within 12 inches of the bottom of the enclosure. In lieu of this requirement, combustion air requirements specified by the manufacturer for a specific power burner appliance may be approved by the building official.
|TOTAL INPUT OF APPLIANCES1, |
THOUSANDS OF Btu/hr
|REQUIRED FREE AREA OF AIR-SUPPLY |
OPENING OR DUCT, SQUARE INCHES
|ACCEPTABLE APPROXIMATE ROUND DUCT |
|25 (8)||7 (4,500)||3 (75)|
|50 (15)||7 (4,500)||3 (75)|
|75 (23)||11 (7,000)||4 (100)|
|100 (30)||14 (9,000)||4 (100)|
|125 (37)||18 (12,000)||5 (125)|
|150 (45)||22 (14,000)||5 (125)|
|175 (53)||25 (16,000)||6 (150)|
|200 (60)||29 (19,000)||6 (150)|
|225 (68)||32 (21,000)||6 (150)|
|250 (75)||36 (23,000)||7 (175)|
|275 (83)||40 (26,000)||7 (175)|
|300 (90)||43 (28,000)||7 (175)|
|325 (98)||47 (30,000)||8 (200)|
|350 (105)||50 (32,000)||8 (200)|
|375 (113)||54 (35,000)||8 (200)|
|400 (120)||58 (37,000)||9 (225)|
- For total inputs falling between listed capacities, use next largest listed input.
- If flexible duct is used, increase the duct diameter by one inch.*
For appliances other than fan-assisted, calculate volume using Equation 3-1.
For fan-assisted appliances, calculate volume using Equation 3-2.
|Iother||=||All appliances other than fan assisted (input in Btu/h).|
|Ifan||=||Fan-assisted appliance (input in Btu/h).|
|ACH||=||Air change per hour (percent of volume of space exchanged per hour, expressed as a decimal).|
For purposes of this calculation, an infiltration rate greater than 0.60 ACH shall not be used in Equations 3-1 and 3-2.
- The ratio of interior spaces shall be the available volume of all communicating spaces divided by the required volume.
- The outdoor size reduction factor shall be one minus the ratio of interior spaces.
- The minimum size of outdoor opening(s) shall be the full size of outdoor opening(s) calculated in accordance with Section 304.6, multiplied by the reduction factor. The minimum dimension of air openings shall be not less than 3 inches (76 mm).
- Ducts shall be of galvanized steel or an equivalent corrosion-resistant material. If flexible duct is used, increase the duct diameter by one inch. Flexible duct shall be stretched with minimal sags.
- Ducts shall terminate in an unobstructed space, allowing free movement of combustion air to the appliances.
- Ducts shall serve a single space.
- Ducts shall not service both upper and lower combustion air openings where both such openings are used. The separation between ducts serving upper and lower combustion air openings shall be maintained to the source of combustion air.
- Ducts shall not terminate in an attic space.
- The remaining space surrounding a chimney liner, gas vent, special gas vent, or plastic piping installed within a masonry, metal or factory-built chimney shall not be used to supply combustion air.
7. Vertical ducts shall not extend through two or more stories without prior approval from the building official.
8. Ducts shall not terminate in the return air plenum of a forced-air heating system unless installed in accordance with the heating equipment manufacturer's installation instructions.
9. Combustion air intake openings shall be located to avoid intake of exhaust air in accordance with IMC Section 401.5 and IFGC Section 503.8 and shall be covered with corrosion-resistant screen of not less than 1/4-inch (6.4 mm) mesh.
10. Combustion air intake openings shall be located at least 12 inches (305 mm) above adjoining grade level.
In barbershops, beauty shops and other facilities where chemicals that generate corrosive or flammable products, such as aerosol sprays, are routinely used, nondirect vent-type appliances shall be located in a mechanical room separated or partitioned off from other areas with provisions for combustion air and dilution air from the outdoors. Direct-vent appliances shall be installed in accordance with the appliance manufacturer's installation instructions.
Unlisted appliances approved in accordance with Section 301.3 shall be limited to uses recommended by the manufacturer and shall be installed in accordance with the manufacturer's instructions, the provisions of this code and the requirements determined by the code official.
Exception: The requirements of this section shall not apply where the appliances are protected from motor vehicle impact and installed in accordance with Section 305.3 and NFPA 30A.
- Overhead heaters where installed not less than 8 feet (2438 mm) above the floor shall be permitted.
- Heating appliances for vehicle repair areas where there is no dispensing or transferring of Class I or II flammable or combustible liquids or liquefied petroleum gas shall be installed in accordance with NFPA 30A.
Exception: Within a dwelling unit, appliances installed in a compartment, alcove, basement or similar space shall be provided with access by an opening or door and an unobstructed passageway measuring not less than 24 inches (610 mm) wide and large enough to allow removal of the largest appliance in the space, provided that a level service space of not less than 30 inches (762 mm) deep and the height of the appliance, but not less than 30 inches (762 mm), is present at the front or service side of the appliance with the door open.
- The passageway and level service space are not required where the appliance is capable of being serviced and removed through the required opening.
- Where the passageway is not less than 6 feet (1829 mm) high for its entire length, the passageway shall be not greater than 50 feet (15 250 mm) in length.
- The passageway is not required where the level service space is present when the access is open and the appliance is capable of being serviced and removed through the required opening.
- Where the passageway is not less than 6 feet high (1829 mm) for its entire length, the passageway shall not be limited in length.
Exception: A portable ladder may be used for dwellings, replacement equipment and appliances on existing buildings, and for exterior roof access points not exceeding 16 feet (4.9 m) above grade, unless the building official determines that the unique shape of the roof does not allow safe access with a portable ladder.
The permanent stair shall be as required by relevant safety regulations, but shall not be less than the following:
- The stair shall be installed at an angle of not more than 60 degrees measured from the horizontal plane.
- The stair shall have flat treads at least 6 inches (152 mm) deep and a clear width of at least 18 inches (457 mm) with equally spaced risers at least 10.5 inches (267 mm) high and not exceeding 14 inches (356 mm).
- The stair shall have intermediate landings not exceeding 18 feet (5.5 m) vertically.
- Continuous handrails shall be installed on both sides of the stair.
- Interior stairs shall terminate at the under side of the roof at a hatch or scuttle of at least 8 square feet (0.74 m2) with a minimum dimension of 20 inches (508 mm).
- When a roof access hatch or scuttle is located within 10 feet (3.0 m) of a roof edge, a guard shall be installed in accordance with IFGC Section 306.6.
- Exterior stairs shall terminate at the roof access point or at a level landing of at least 8 square feet (0.74 m2) with a minimum dimension of 20 inches (508 mm). The landing shall have a guard installed in accordance with IFGC Section 306.6.
- Width shall be at least 16 inches (406 mm).
- Rung spacing shall be a maximum of 14 inches (356 mm).
- Toe space shall be at least 6 inches (152 mm).
- Side railings shall extend at least 30 inches (762 mm) above the roof or parapet wall.
|TYPE OF PROTECTION APPLIED TO |
AND COVERING ALL SURFACES OF COMBUSTIBLE
MATERIAL WITHIN THE DISTANCE SPECIFIED AS THE
REQUIRED CLEARANCE WITH NO PROTECTION
[see Figures 308.2(1), 308.2(2), and 308.2(3)]
|WHERE THE REQUIRED CLEARANCE WITH NO PROTECTION FROM |
APPLIANCE, VENT CONNECTOR, OR SINGLE-WALL METAL PIPE IS: (inches)
|Allowable clearances with specified protection (inches)|
|Use Column 1 for clearances above appliance or horizontal connector. Use Column 2 |
for clearances from appliance, vertical connector and single-wall metal pipe.
|1. 31/2-inch-thick masonry wall without ventilated |
|2. 1/2-inch insulation board over 1-inch glass fiber or |
mineral wool batts
|3. 0.024-inch (nominal 24 gage) sheet metal over 1-inch |
glass fiber or mineral wool batts reinforced with wire
on rear face with ventilated airspace
|4. 31/2-inch-thick masonry wall with ventilated airspace||—||12||—||6||—||6||—||6||—||6|
|5. 0.024-inch (nominal 24 gage) sheet metal with |
|6. 1/2-inch-thick insulation board with ventilated |
|7. 0.024-inch (nominal 24 gage) sheet metal with |
ventilated airspace over 0.024-inch (nominal 24 gage)
sheet metal with ventilated airspace
|8. 1-inch glass fiber or mineral wool batts sandwiched |
between two sheets 0.024-inch (nominal 24 gage)
sheet metal with ventilated airspace
|For SI: 1 inch = 25.4 mm, °C = [(°F - 32)/1.8], 1 pound per cubic foot = 16.02 kg/m3, 1 Btu per inch per square foot per hour per °F = 0.144 W/m2 • K.|
|a. Reduction of clearances from combustible materials shall not interfere with combustion air, draft hood clearance and relief, and accessibility of servicing.|
|b. All clearances shall be measured from the outer surface of the combustible material to the nearest point on the surface of the appliance, disregarding any intervening protection applied to the combustible material.|
|c. Spacers and ties shall be of noncombustible material. No spacer or tie shall be used directly opposite an appliance or connector.|
|d. For all clearance reduction systems using a ventilated airspace, adequate provision for air circulation shall be provided as described [see Figures 308.2(2) and 308.2(3)].|
|e. There shall be at least 1 inch between clearance reduction systems and combustible walls and ceilings for reduction systems using ventilated airspace.|
|f. Where a wall protector is mounted on a single flat wall away from corners, it shall have a minimum 1-inch air gap. To provide air circulation, the bottom and top edges, or only the side and top edges, or all edges shall be left open.|
|g. Mineral wool batts (blanket or board) shall have a minimum density of 8 pounds per cubic foot and a minimum melting point of 1500°F.|
|h. Insulation material used as part of a clearance reduction system shall have a thermal conductivity of 1.0 Btu per inch per square foot per hour per °F or less.|
|i. There shall be at least 1 inch between the appliance and the protector. In no case shall the clearance between the appliance and the combustible surface be reduced below that allowed in this table.|
|j. All clearances and thicknesses are minimum; larger clearances and thicknesses are acceptable.|
|k. Listed single-wall connectors shall be installed in accordance with the manufacturer's installation instructions.|
|"A" equals the clearance with no protection.|
|"B" equals the reduced clearance permitted in accordance with Table 308.2.|
|The protection applied to the construction using combustible material shall extend far enough in each direction to make "C" equal to "A."|
|For SI: 1 inch = 25.4 mm.|
|For SI: 1 inch = 25.4 mm.|