Page 37 - 2015_IWUI

SPECIAL BUILDING CONSTRUCTION REGULATIONS

have underfloor areas enclosed to within 6 inches (152 Such material shall extend from the top of the foundation
mm) of the ground, with exterior wall construction in to the underside of the roof sheathing.
accordance with Section 504.5 or underfloor protection in 505.6 Underfloor enclosure. Buildings or structures shall
accordance with Section 504.6.
have underfloor areas enclosed to the ground, with exterior
Exception: The enclosure shall not be required where walls in accordance with Section 505.5.
the underside of exposed floors and exposed structural Exception: Complete enclosure shall not be required
columns, beams and supporting walls are protected as
where the underside of exposed floors and exposed struc-
required for exterior 1-hour fire-resistance-rated con- tural columns, beams and supporting walls are protected
struction or heavy-timber construction or fire-retardant-
as required for exterior 1-hour fire-resistance-rated con-
treated wood on the exterior side. The fire-retardant- struction or heavy timber construction or fire-retardant-
treated wood shall be labeled for exterior use and meet treated wood. The fire-retardant-treated wood shall be
the requirements of Section 2303.2 of the International labeled for exterior use and meet the requirements of Sec-
Building Code.
tion 2303.2 of the International Building Code.
505.7 Appendages and projections. Unenclosed accessory
SECTION 505 structures attached to buildings with habitable spaces and
CLASS 2 IGNITION-RESISTANT CONSTRUCTION projections, such as decks, shall be not less than 1-hour fire-
resistance-rated construction, heavy timber construction or
505.1 General. Class 2 ignition-resistant construction shall constructed of one of the following:
be in accordance with Sections 505.2 through 505.11.
1. Approved noncombustible materials.
505.2 Roof covering. Roofs shall have at least a roof assem-
bly that complies with a Class B rating when tested in accor- 2. Fire-retardant-treated wood identified for exterior use
dance with ASTM E 108 or UL 790 or an approved and meeting the requirements of Section 2303.2 of the
noncombustible roof covering. For roof coverings where the International Building Code.
profile allows a space between the roof covering and roof 3. Ignition-resistant building materials in accordance with
decking, the space at the eave ends shall be firestopped to Section 503.2.
preclude entry of flames or embers, or have one layer of 72- 505.7.1 Underfloor areas. Where the attached structure is
pound (32.4 kg) mineral-surfaced, nonperforated cap sheet located and constructed so that the structure or any portion
complying with ASTM D 3909 installed over the combusti- thereof projects over a descending slope surface greater
ble decking. than 10 percent, the area below the structure shall have
505.2.1 Roof valleys. Where provided, valley flashings underfloor areas enclosed to within 6 inches (152 mm) of
shall be not less than 0.019-inch (0.48 mm) (No. 26 galva- the ground, with exterior wall construction in accordance
nized sheet gage) corrosion-resistant metal installed over a with Section 505.5.
minimum 36-inch-wide (914 mm) underlayment consist- 505.8 Exterior glazing. Exterior windows, window walls
ing of one layer of 72-pound (32.4 kg) mineral-surfaced, and glazed doors, windows within exterior doors, and sky-
nonperforated cap sheet complying with ASTM D 3909 lights shall be tempered glass, multilayered glazed panels,
running the full length of the valley. glass block or have a fire protection rating of not less than 20
505.3 Protection of eaves. Combustible eaves, fascias and minutes.
soffits shall be enclosed with solid materials with a minimum 505.9 Exterior doors. Exterior doors shall be approved non-
3
thickness of / inch (19 mm). Exposed rafter tails shall not be combustible construction, solid core wood not less than 1 /
3
4 4
permitted unless constructed of heavy timber materials. inches thick (45 mm), or have a fire protection rating of not
less than 20 minutes. Windows within doors and glazed doors
505.4 Gutters and downspouts. Gutters and downspouts
shall be constructed of noncombustible material. Gutters shall shall be in accordance with Section 505.8.
be provided with an approved means to prevent the accumu- Exception: Vehicle access doors.
lation of leaves and debris in the gutter.
505.10 Vents. Attic ventilation openings, foundation or
505.5 Exterior walls. Exterior walls of buildings or struc- underfloor vents or other ventilation openings in vertical
tures shall be constructed with one of the following methods: exterior walls and vents through roofs shall not exceed 144
2
square inches (0.0929 m ) each. Such vents shall be covered
1. Materials approved for a minimum of 1-hour fire-resis- with noncombustible corrosion-resistant mesh with openings
tance-rated construction on the exterior side. 1
not to exceed / inch (6.4 mm) or shall be designed and
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2. Approved noncombustible materials. approved to prevent flame or ember penetration into the
structure.
3. Heavy timber or log wall construction.
505.10.1 Vent locations. Attic ventilation openings shall
4. Fire-retardant-treated wood on the exterior side. The not be located in soffits, in eave overhangs, between raf-
fire-retardant-treated wood shall be labeled for exterior ters at eaves, or in other overhang areas. Gable end and
use and meet the requirements of Section 2303.2 of the dormer vents shall be located not less than 10 feet (3048
International Building Code.
mm) from lot lines. Underfloor ventilation openings shall
5. Ignition-resistant materials on the exterior side. be located as close to grade as practical.
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22 2015 INTERNATIONAL WILDLAND-URBAN INTERFACE CODE
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