R703.3 Nominal Thickness and Attachments

The nominal thickness and attachment of exterior wall coverings shall be in accordance with Table R703.3(1), the wall covering material requirements of this section, and the wall covering manufacturer's installation instructions. Cladding attachment over foam sheathing shall comply with the additional requirements and limitations of Sections R703.15 through R703.17. Nominal material thicknesses in Table R703.3(1) are based on a maximum stud spacing of 16 inches (406 mm) on center. Where specified by the siding manufacturer's instructions and supported by a test report or other documentation, attachment to studs with greater spacing is permitted. Fasteners for exterior wall coverings attached to wood framing shall be in accordance with Section R703.3.2 and Table R703.3(1). Exterior wall coverings shall be attached to cold-formed steel light frame construction in accordance with the cladding manufacturer's installation instructions, the requirements of Table R703.3(1) using screw fasteners substituted for the nails specified in accordance with Table R703.3(2), or an approved design.

TABLE R703.3(1)
SIDING MINIMUM ATTACHMENT AND MINIMUM THICKNESS

SIDING MATERIAL		NOMINAL THICKNESS (inches)	JOINT TREATMENT	TYPE OF SUPPORTS FOR THE SIDING MATERIAL AND FASTENERS
				Wood or wood structural panel sheathing into stud	Fiberboard sheathing into stud	Gypsum sheathing into stud	Foam plastic sheathing into studl	Direct to studs	Number or spacing of fasteners
Anchored veneer: brick, concrete, masonry or stone (see Section R703.8)		2	Section R703.8	Section R703.8
Adhered veneer: concrete, stone or masonry (see Section R703.12)		—	Section R703.12	Section R703.12
Fiber cement siding	Panel siding (see Section R703.10.1)	5/16	Section R703.10.1	6d common (2" × 0.113")	6d common (2" × 0.113")	6d common (2" × 0.113")	6d common (2" × 0.113")	4d common (11/2" × 0.099")	6" panel edges 12" inter. sup.
	Lap siding (see Section R703.10.2)	5/16	Section R703.10.2	6d common (2" × 0.113")	6d common (2" × 0.113")	6d common (2" × 0.113")	6d common (2" × 0.113")	6d common (2" × 0.113") or 11 gage roofing nail	Note f
Hardboard panel siding (see Section R703.5)		7/16	—	0.120" nail (shank) with 0.225" head	0.120" nail (shank) with 0.225" head	0.120" nail (shank) with 0.225" head	0.120" nail (shank) with 0.225" head	0.120" nail (shank) with 0.225" head	6" panel edges 12" inter. sup.d
Hardboard lap siding (see Section R703.5)		7/16	Note e	0.099" nail (shank) with 0.240" head	0.099" nail (shank) with 0.240" head	0.099" nail (shank) with 0.240" head	0.099" nail (shank) with 0.240" head	0.099" nail (shank) with 0.240" head	Same as stud spacing 2 per bearing
Horizontal aluminuma	Without insulation	0.019b	Lap	Siding nail 11/2" × 0.120"	Siding nail 2" × 0.120"	Siding nail 2" × 0.120"	Siding nailh 11/2" × 0.120"	Not allowed	Same as stud spacing
		0.024	Lap	Siding nail 11/2" × 0.120"	Siding nail 2" × 0.120"	Siding nail 2" × 0.120"	Siding nailh 11/2" × 0.120"	Not allowed
	With insulation	0.019	Lap	Siding nail 11/2" × 0.120"	Siding nail 21/2" × 0.120"	Siding nail 21/2" × 0.120"	Siding nailh 11/2" × 0.120"	Siding nail 11/2" × 0.120"
Insulated vinyl sidingj		0.035 (vinyl siding layer only)	Lap	0.120 nail (shank) with a 0.313 head or 16-gage crownh, i	0.120 nail (shank) with a 0.313 head or 16-gage crownh	0.120 nail (shank) with a 0.313 head or 16-gage crownh	0.120 nail (shank) with a 0.313 head Section R703.11.2	Not allowed	16 inches on center or specified by manufacturer instructions, test report or other sections of this code
Particleboard panels		3/8	—	6d box nail (2" × 0.099")	6d box nail (2" × 0.099")	6d box nail (2" × 0.099")	6d box nail (2" × 0.099")	Not allowed	6" panel edges 12" inter. sup.
		1/2	—	6d box nail (2" × 0.099")	6d box nail (2" × 0.099")	6d box nail (2" × 0.099")	6d box nail (2" × 0.099")	6d box nail (2" × 0.099")
		5/8	—	6d box nail (2" × 0.099")	8d box nail (21/2" × 0.113")	8d box nail (21/2" × 0.113")	6d box nail (2" × 0.099")	6d box nail (2" × 0.099")
Polypropylene sidingk		Not applicable	Lap	Section 703.14.1	Section 703.14.1	Section 703.14.1	Section 703.14.1	Not allowed	As specified by the manufacturer instructions, test report or other sections of this code
Steelc		29 ga.	Lap	Siding nail (13/4" × 0.113") Staple—13/4"	Siding nail (23/4" × 0.113") Staple—21/2"	Siding nail (21/2" × 0.113") Staple—21/4"	Siding nail (13/4" x 0.113") Staple—13/4"	Not allowed	Same as stud spacing
Vinyl siding (see Section R703.11)		0.035	Lap	0.120" nail (shank) with a 0.313" head or 16-gage staple with 3/8- to 1/2-inch crownh, i	0.120" nail (shank) with a 0.313" head or 16-gage staple with 3/8- to 1/2- inch crownh	0.120" nail (shank) with a 0.313" head or 16- gage staple with 3/8- to 1/2- inch crownh	0.120" nail (shank) with a 0.313 head Section R703.11.2	Not allowed	16 inches on center or as specified by the manufacturer instructions or test report
Wood siding (see Section R703.5)	Wood rustic, drop	3/8 min.	Lap	6d box or siding nail (2" × 0.099")	6d box or siding nail (2" × 0.099")	6d box or siding nail (2" × 0.099")	6d box or siding nail (2" × 0.099")	8d box or siding nail (21/2" × 0.113") Staple—2"	Face nailing up to 6" widths, 1 nail per bearing; 8" widths and over, 2 nails per bearing
	Shiplap	19/32 average	Lap
	Bevel	7/16
	Butt tip	3/16	Lap
Wood structural panel ANSI/APA PRP-210 siding (exterior grade) (see Section R703.5)		3/8 — 1/2	Note e	2" × 0.099" siding nail	21/2" × 0.113" siding nail	21/2" × 0.113" siding nail	21/2" × 0.113" siding nail	2" × 0.099" siding nail	6" panel edges 12" inter. sup.
Wood structural panel lap siding (see Section R703.5)		3/8 — 1/2	Note e Note g	2" × 0.099" siding nail	21/2" × 0.113" siding nail	21/2" × 0.113" siding nail	21/2" × 0.113" siding nail	2" × 0.099" siding nail	8" along bottom edge

TABLE R703.3(2)
SCREW FASTENER SUBSTITUTION FOR SIDING ATTACHMENT TO COLD-FORMED STEEL LIGHT FRAME CONSTRUCTION^{a, b, c, d, e}

NAIL DIAMETER PER TABLE R703.3(1)	MINIMUM SCREW FASTENER SIZE
0.099"	No. 6
0.113"	No. 7
0.120"	No. 8

Where the design wind pressure exceeds 30 psf or where the limits of Table R703.3.1 are exceeded, the attachment of wall coverings shall be designed to resist the component and cladding loads specified in Table R301.2(2), adjusted for height and exposure in accordance with Table R301.2(3). For the determination of wall covering attachment, component and cladding loads shall be determined using an effective wind area of 10 square feet (0.93 m²).

TABLE R703.3.1
LIMITS FOR ATTACHMENT PER TABLE R703.3(1)

MAXIMUM MEAN ROOF HEIGHT
Ultimate Wind Speed (mph 3-second gust)	Exposure
	B	C	D
115	NL	50'	20'
120	NL	30'	DR
130	60'	15'	DR
140	35'	DR	DR

Exterior wall coverings shall be securely fastened with aluminum, galvanized, stainless steel or rust-preventative coated nails or staples in accordance with Table R703.3(1) or with other approved corrosion-resistant fasteners in accordance with the wall covering manufacturer's installation instructions. Nails and staples shall comply with ASTM F1667. Nails shall be T-head, modified round head, or round head with smooth or deformed shanks. Staples shall have a minimum crown width of ⁷/₁₆ inch (11.1 mm) outside diameter and be manufactured of minimum 16-gage wire. Where fiberboard, gypsum, or foam plastic sheathing backing is used, nails or staples shall be driven into the studs. Where wood or wood structural panel sheathing is used, fasteners shall be driven into studs unless otherwise permitted to be driven into sheathing in accordance with either the siding manufacturer's installation instructions or Table R703.3.2.

TABLE R703.3.2
OPTIONAL SIDING ATTACHMENT SCHEDULE FOR FASTENERS WHERE NO STUD PENETRATION NECESSARY

APPLICATION	NUMBER AND TYPE OF FASTENER	SPACING OF FASTENERSb
Exterior wall covering (weighing 3 psf or less) attachment to wood structural panel sheathing, either direct or over foam sheathing a maximum of 2 inches thick.a Note: Does not apply to vertical siding.	Ring shank roofing nail (0.120" min. dia.)	12" o.c.
	Ring shank nail (0.148" min. dia.)	15" o.c.
	No. 6 screw (0.138" min. dia.)	12" o.c.
	No. 8 screw (0.164" min. dia.)	16" o.c.