Page 408 - 2018_IRC

CHAPTER 8

ROOF-CEILING CONSTRUCTION

User note:
About this chapter: Chapter 8 addresses the design and construction of roof-ceiling systems. This chapter contains two roof-ceiling framing
systems: wood framing and cold-formed steel framing. Allowable span tables are provided to simplify the selection of rafter and ceiling joist
size for wood roof framing and cold-formed steel framing. Chapter 8 also provides requirements for the application of ceiling finishes, the
proper ventilation of concealed spaces in roofs (for example, enclosed attics and rafter spaces), unvented attic assemblies and attic access.

SECTION R801 R802.1.4 Structural composite lumber. Structural
GENERAL capacities for structural composite lumber shall be estab-
lished and monitored in accordance with ASTM D5456.
R801.1 Application. The provisions of this chapter shall
control the design and construction of the roof-ceiling system R802.1.5 Fire-retardant-treated wood. Fire-retardant-
for buildings. treated wood (FRTW) is any wood product that, when
impregnated with chemicals by a pressure process or other
R801.2 Requirements. Roof and ceiling construction shall
be capable of accommodating all loads imposed in accor- means during manufacture, shall have, when tested in
dance with Section R301 and of transmitting the resulting accordance with ASTM E84 or UL 723, a listed flame
spread index of 25 or less and does not show evidence of
loads to the supporting structural elements.
significant progressive combustion where the test is contin-
R801.3 Roof drainage. In areas where expansive soils or col- ued for an additional 20-minute period. In addition, the
lapsible soils are known to exist, all dwellings shall have a flame front shall not progress more than 10.5 feet (3200
controlled method of water disposal from roofs that will col- mm) beyond the center line of the burners at any time during
lect and discharge roof drainage to the ground surface not less the test.
than 5 feet (1524 mm) from foundation walls or to an approved R802.1.5.1 Pressure process. For wood products
drainage system. impregnated with chemicals by a pressure process, the
process shall be performed in closed vessels under
pressures not less than 50 pounds per square inch gauge
SECTION R802 (psig) (344.7 kPa).
WOOD ROOF FRAMING
R802.1.5.2 Other means during manufacture. For
R802.1 General. Wood and wood-based products used for wood products produced by other means during manu-
load-supporting purposes shall conform to the applicable pro- facture the treatment shall be an integral part of the
visions of this section. manufacturing process of the wood product. The treat-
R802.1.1 Sawn lumber. Sawn lumber shall be identified ment shall provide permanent protection to all surfaces
by a grade mark of an accredited lumber grading or of the wood product.
inspection agency and have design values certified by an R802.1.5.3 Testing. For wood products produced by
accreditation body that complies with DOC PS 20. In lieu other means during manufacture, other than a pressure
of a grade mark, a certificate of inspection issued by a process, all sides of the wood product shall be tested in
lumber grading or inspection agency meeting the require- accordance with and produce the results required in
ments of this section shall be accepted. Section R802.1.5. Testing of only the front and back
R802.1.1.1 End-jointed lumber. Approved end- faces of wood structural panels shall be permitted.
jointed lumber identified by a grade mark conforming R802.1.5.4 Labeling. In addition to the labels required
to Section R802.1.1 shall be permitted to be used inter- by Section 802.1.1 for sawn lumber and Section
changeably with solid-sawn members of the same spe- 803.2.1 for wood structural panels, each piece of fire-
cies and grade. End-jointed lumber used in an assembly retardant-treated lumber and wood structural panel
required elsewhere in this code to have a fire-resistance shall be labeled. The label shall contain:
rating shall have the designation “Heat-Resistant Adhe-
sive” or “HRA” included in its grade mark. 1. The identification mark of an approved agency in
accordance with Section 1703.5 of the Interna-
R802.1.2 Structural glued-laminated timbers. Glued- tional Building Code.
laminated timbers shall be manufactured and identified as
required in ANSI A190.1, ANSI 117 and ASTM D3737. 2. Identification of the treating manufacturer.
3. The name of the fire-retardant treatment.
R802.1.3 Structural log members. Structural log mem-
bers shall comply with the provisions of ICC 400. 4. The species of wood treated.

2018 INTERNATIONAL RESIDENTIAL CODE ® 383
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