Section 2306 Allowable Stress Design

The design and construction of wood elements in structures using allowable stress design shall be in accordance with the following applicable standards:

American Wood Council.

American Society of Agricultural and Biological Engineers.

APA—The Engineered Wood Association.

Truss Plate Institute, Inc.

West Coast Lumber Inspection Bureau

The allowable unit stresses for preservative-treated wood need not be adjusted for treatment, but are subject to other adjustments.

The allowable unit stresses for fire-retardant-treated wood, including fastener values, shall be developed from an approved method of investigation that considers the effects of anticipated temperature and humidity to which the fire-retardant-treated wood will be subjected, the type of treatment and the redrying process. Other adjustments are applicable except that the impact load duration shall not apply.

The capacity of lumber decking arranged according to the patterns described in Section 2304.9.2 shall be the lesser of the capacities determined for flexure and deflection according to the formulas in Table 2306.1.4.

PATTERN	ALLOWABLE AREA LOADa, b
	Flexure	Deflection
Simple span
Two-span continuous
Combination simple- and two-span continuous
Cantilevered pieces intermixed
Controlled random layup
Mechanically laminated decking
2-inch decking
3-inch and 4-inch decking

For SI: 1 inch = 25.4 mm.

1. σ_b = Allowable total uniform load limited by bending.
   
   σ_Δ = Allowable total uniform load limited by deflection.
2. d = Actual decking thickness.
   
   l = Span of decking.
   
   F_b' = Allowable bending stress adjusted by applicable factors.
   
   E' = Modulus of elasticity adjusted by applicable factors.

Wood-frame diaphragms shall be designed and constructed in accordance with AWC SDPWS. Where panels are fastened to framing members with staples, requirements and limitations of AWC SDPWS shall be met and the allowable shear values set forth in Table 2306.2(1) or 2306.2(2) shall be permitted. The allowable shear values in Tables 2306.2(1) and 2306.2(2) are permitted to be increased 40 percent for wind design.

PANEL GRADE	STAPLE LENGTH AND GAGEd	MINIMUM FASTENER PENETRATION IN FRAMING (inches)	MINIMUM NOMINAL PANEL THICKNESS (inch)	MINIMUM NOMINAL WIDTH OF FRAMING MEMBERS AT ADJOINING PANEL EDGES AND BOUNDARIESe (inches)	BLOCKED DIAPHRAGMS				UNBLOCKED DIAPHRAGMS
					Fastener spacing (inches) at diaphragm boundaries (all cases) at continuous panel edges parallel to load (Cases 3, 4), and at all panel edges (Cases 5, 6)b				Fasteners spaced 6 max. at supported edgesb
					6	4	21/2c	2c	Case 1 (No unblocked edges or continuous joints parallel to load)	All other configurations (Cases 2, 3, 4, 5 and 6)
					Fastener spacing (inches) at other panel edges (Cases 1, 2, 3 and 4)b
					6	6	4	3
Structural I grades	11/2 16 gage	1	3/8	2	175	235	350	400	155	115
				3	200	265	395	450	175	130
			15/32	2	175	235	350	400	155	120
				3	200	265	395	450	175	130
Sheathing, single floor and other grades covered in DOC PS 1 and PS 2	11/2 16 gage	1	3/8	2	160	210	315	360	140	105
				3	180	235	355	400	160	120
			7/16	2	165	225	335	380	150	110
				3	190	250	375	425	165	125
			15/32	2	160	210	315	360	140	105
				3	180	235	355	405	160	120
			19/32	2	175	235	350	400	155	115
				3	200	265	395	450	175	130

For SI: 1 inch = 25.4 mm, 1 pound per foot = 14.5939 N/m.

1. For framing of other species: (1) Find specific gravity for species of lumber in ANSI/AWC NDS. (2) For staples find shear value from table for Structural I panels (regardless of actual grade) and multiply value by 0.82 for species with specific gravity of 0.42 or greater, or 0.65 for all other species.
2. Space fasteners maximum 12 inches on center along intermediate framing members (6 inches on center where supports are spaced 48 inches on center).
3. Framing at adjoining panel edges shall be 3 inches nominal or wider.
4. Staples shall have a minimum crown width of ⁷/₁₆ inch and shall be installed with their crowns parallel to the long dimension of the framing members.
5. The minimum nominal width of framing members not located at boundaries or adjoining panel edges shall be 2 inches.
6. For shear loads of normal or permanent load duration as defined by the ANSI/AWC NDS, the values in the table shall be multiplied by 0.63 or 0.56, respectively.

PANEL GRADEc	STAPLE GAGEf	MINIMUM FASTENER PENETRATION IN FRAMING (inches)	MINIMUM NOMINAL PANEL THICKNESS (inch)	MINIMUM NOMINAL WIDTH OF FRAMING MEMBER AT ADJOINING PANEL EDGES AND BOUNDARIESe	LINES OF FASTENERS	BLOCKED DIAPHRAGMS
						Cases 1 and 2d
						Fastener Spacing Per Line at Boundaries (inches)
						4		21/2		2
						Fastener Spacing Per Line at Other Panel Edges (inches)
						6	4	4	3	3	2
Structural I grades	14 gage staples	2	15/32	3	2	600	600	860	960	1,060	1,200
				4	3	860	900	1,160	1,295	1,295	1,400
			19/32	3	2	600	600	875	960	1,075	1,200
				4	3	875	900	1,175	1,440	1,475	1,795
Sheathing single floor and other grades covered in DOC PS 1 and PS 2	14 gage staples	2	15/32	3	2	540	540	735	865	915	1,080
				4	3	735	810	1,005	1,105	1,105	1,195
			19/32	3	2	600	600	865	960	1,065	1,200
				4	3	865	900	1,130	1,430	1,370	1,485
			23/32	4	3	865	900	1,130	1,490	1,430	1,545

For SI: 1 inch = 25.4 mm, 1 pound per foot = 14.5939 N/m.

1. For framing of other species: (1) Find specific gravity for species of framing lumber in ANSI/AWC NDS. (2) For staples, find shear value from table for Structural I panels (regardless of actual grade) and multiply value by 0.82 for species with specific gravity of 0.42 or greater, or 0.65 for all other species.
2. Fastening along intermediate framing members: Space fasteners not greater than 12 inches on center, except 6 inches on center for spans greater than 32 inches.
3. Panels conforming to PS 1 or PS 2.
4. This table gives shear values for Cases 1 and 2 as shown in Table 2306.2(1). The values shown are applicable to Cases 3, 4, 5 and 6 as shown in Table 2306.2(1), providing fasteners at all continuous panel edges are spaced in accordance with the boundary fastener spacing.
5. The minimum nominal depth of framing members shall be 3 inches nominal. The minimum nominal width of framing members not located at boundaries or adjoining panel edges shall be 2 inches.
6. Staples shall have a minimum crown width of ⁷/₁₆ inch, and shall be installed with their crowns parallel to the long dimension of the framing members.
7. High-load diaphragms shall be subject to special inspection in accordance with Section 1705.5.1.
8. For shear loads of normal or permanent load duration as defined by the ANSI/AWC NDS, the values in the table shall be multiplied by 0.63 or 0.56, respectively.