Code of Massachusetts Regulations › 780 CMR - STATE BOARD OF BUILDING REGULATIONS AND STANDARDS › Chapter 23 - Wood › Section 2306 - ALLOWABLE STRESS DESIGN › Subsection 2306.2 - Wood diaphragms

Current through Register 1525, July 5, 2024
2306.2.1
Wood structural panel
				diaphragms.
Wood structural panel diaphragms shall be designed and
				constructed in accordance with AF & PA SDPWS. Wood structural panel
				diaphragms are permitted to resist horizontal forces using the allowable shear
				capacities set forth in Table 2306.2.1(1) or 2306.2.1(2). The allowable shear
				capacities in Tables 2306.2.1(1) and 2306.2.1(2) are permitted to be increased
				40 percent for wind design.
TABLE 2306.2.1(1) ALLOWABLE SHEAR (POUNDS PER FOOT) FOR
				  WOOD STRUCTURAL PANEL DIAPHRAGMS WITH FRAMING OF DOUGLAS FIR-LARCH, OR SOUTHERN
				  PINEa FOR WIND OR SEISMIC
				  LOADINGh
PANEL GRADE
COMMON NAIL SIZE OR STAPLEf LENGTH
							 AND GAGE
MINIMUM FASTENER PENETRATION IN
							 FRAMING (inches)
MINIMUM NOMINAL PANEL THICKNESS
							 (inch)
MINIMUM NOMINAL
WIDTH
							 OF FRAMING MEMBERS AT ADJOINING PANEL
EDGES AND
							 BOUNDARIESg (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
2 1/2c
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
8d (2 1/2" x 0.131")
1 3/8
3/8
2
270
360
530
600
240
180
3
300
400
600
675
265
200
11/2 16 Gage
1
2
175
235
350
400
155
115
3
200
265
395
450
175
130
10dd (3" x 0.148")
1 1/2
15/32
2
320
425
640
730
285
215
3
360
480
720
820
320
240
11/2 16 Gage
1
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
6de (2" x 0.113")
11/4
3/8
2
185
250
375
420
165
125
8d (21/2" x 0.131")
13/8
3
210
280
420
475
185
140
2
240
320
480
545
215
160
3
270
360
540
610
240
180
11/2 16 Gage
1
2
160
210
315
360
140
105
3
180
235
355
400
160
120
8d (2 1/2" x 0.131")
1 3/8
7/16
2
255
340
505
575
230
170
3
285
380
570
645
255
190
11/2 16 Gage
1
2
165
225
335
380
150
110
3
190
250
375
425
165
125
8d (2 1/2" x 0.131")
1 3/8
15/32
2
270
360
530
600
240
180
3
300
400
600
675
265
200
10dd (3" x 0.148")
11/2
2
290
385
575
655
255
190
3
325
430
650
735
290
215
11/2 16 Gage
1
2
160
210
315
360
140
105
3
180
235
355
405
160
120
10dd (3" x 0.148")
11/2
19/32
2
320
425
640
730
285
215
3
360
480
720
820
320
240
13/4 16 Gage
1
2
175
235
350
400
155
115
3
200
265
395
450
175
130
TABLE 2306.2.1(1)-continued-ALLOWABLE SHEAR (POUNDS PER
				  FOOT) FOR WOOD STRUCTURAL PANEL DIAPHRAGMS WITH FRAMING OF DOUGLAS FIR-LARCH,
				  OR SOUTHERN PINEa FOR WIND OR SEISMIC
				  LOADINGh
Click to view
							 image
For SI: 1 inch = 25.4 mm, 1 pound per foot = 14.5939
							 N/m.
a. For framing of other species: (1) Find specific gravity
							 for species of lumber in AF & PA NDS. (2) For staples find shear value from
							 table above 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. (3) For nails find shear value from table above for nail
							 size for actual grade and multiply value by the following adjustment factor:
							 Specific Gravity Adjustment Factor = [1-(0.5 - SG)], where SG = Specific
							 Gravity of the framing lumber. This adjustment factor shall not be greater than
							 1.
b. Space fasteners maximum 12 inches o.c. along intermediate
							 framing members (6 inches o.c. where supports are spaced 48 inches o.c.).
c. Framing at adjoining panel edges shall be 3 inches nominal or
							 wider, and nails at all panel edges shall be staggered where panel edge nailing
							 is specified at 21/2 inches o.c. or less.
d. Framing at adjoining
							 panel edges shall be 3 inches nominal or wider, and nails at all panel edges
							 shall be staggered where both of the following conditions are met: (1) 10d
							 nails having penetration into framing of more than 11/2 inches and (2) panel
							 edge nailing is specified at 3 inches o.c. or less.
e. 8d is
							 recommended minimum for roofs due to negative pressures of high winds.
f. 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.
g. The minimum nominal width of framing members not
							 located at boundaries or adjoining panel edges shall be 2 inches.
h. For shear loads of normal or permanent load duration as defined by the AF
							 & PA NDS, the values in the table above shall be multiplied by 0.63 or
							 0.56, respectively.
TABLE 2306.2.1(2) ALLOWABLE SHEAR (POUNDS PER FOOT) FOR
				  WOOD STRUCTURAL PANEL BLOCKED DIAPHRAGMS UTILIZING MULTIPLE ROWS OF FASTENERS
				  (HIGH LOAD DIAPHRAGMS) WITH FRAMING OF DOUGLAS FIR-LARCH OR SOUTHERN
				  PINEa FOR WIND OR SEISMIC LOADINGb, g,
				  h
PANEL
							 GRADEc
COMMON NAIL SIZE OR
							 STAPLEf GAGE
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
10d common nails
11/2
15/32
3
4
4
2
2
3
605
700
875
815
915
1,220
875
1,005
1,285
1,150
1,290
1,395
-
-
-
-
-
-
19/32
3
4
4
2
2
3
670
780
965
880
990
1,320
965
1,110
1,405
1,255
1,440
1,790
-
-
-
-
-
-
23/32
3
4
4
2
2
3
730
855
1,050
955
1,070
1,430
1,050
1,210
1,525
1,365
1,565
1,800
-
-
-
-
-
-
14 gage staples
2
15/32
3
4
2
3
600
860
600
900
860
1,160
960
1,295
1,060
1,295
1,200
1,400
19/32
3
4
2
3
600
875
600
900
875
1,175
960
1,440
1,075
1,475
1,200
1,795
Sheathing single floor and other grades
							 covered in DOC PS 1 and PS 2
10d common nails
11/2
15/32
3
4
4
2
2
3
525
605
765
725
815
1,085
765
875
1,130
1,010
1,105
1,195
-
-
-
-
-
-
19/32
3
4
4
2
2
3
650
755
935
860
965
1,290
935
1,080
1,365
1,225
1,370
1,485
-
-
-
-
-
-
23/32
3
4
4
2
2
3
710
825
1,020
935
1,050
1,400
1,020
1,175
1,480
1,335
1,445
1,565
-
-
-
-
-
-
14 gage staples
2
15/32
3
4
2
3
540
735
540
810
735
1,005
865
1,105
915
1,105
1,080
1,195
19/32
3
4
2
3
600
865
600
900
865
1,130
960
1,430
1,065
1,370
1,200
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.
a. For framing of other species: (1) Find specific gravity
							 for species of framing lumber in AF & PA NDS. (2) For staples, find shear
							 value from table above 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. (3) For nails, find shear value from table above
							 for nail size of actual grade and multiply value by the following adjustment
							 factor: Specific Gravity Adjustment Factor = [ 1- (0.5 - SG)], where SG =
							 Specific gravity of the framing lumber. This adjustment factor shall not be
							 greater than 1.
b. Fastening along intermediate framing members:
							 Space fasteners a maximum of 12 inches on center, except 6 inches on center for
							 spans greater than 32 inches.
c. Panels conforming to PS 1 or PS
							 2.
d. This table gives shear values for Cases 1 and 2 as shown in
							 Table 2306.2.1(1). The values shown are applicable to Cases 3, 4, 5 and 6 as
							 shown in Table 2306.2.1(1), providing fasteners at all continuous panel edges
							 are spaced in accordance with the boundary fastener spacing.
e.
							 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.
f. 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.
g. High load diaphragms
							 shall be subject to special inspection in accordance with Section 1704.6.1.
h. For shear loads of normal or permanent load duration as defined
							 by the AF & PA NDS, the values in the table above shall be multiplied by
							 0.63 or 0.56, respectively.
TABLE 2306.2.1(2)-continued-ALLOWABLE SHEAR (POUNDS
				  PER FOOT) FOR WOOD STRUCTURAL PANEL BLOCKED DIAPHRAGMS UTILIZING MULTIPLE ROWS
				  OF FASTENERS (HIGH LOAD DIAPHRAGMS) WITH FRAMING OF DOUGLAS FIR-LARCH OR
				  SOUTHERN PINE FOR WIND OR SEISMIC LOADING
Click to view
							 image
2306.2.2
Single diagonally sheathed
				lumber diaphragms.
Single diagonally sheathed lumber diaphragms shall be
				designed and constructed in accordance with AF & PA SDPWS.
2306.2.3
Double diagonally sheathed
				lumber diaphragms.
Double diagonally sheathed lumber diaphragms shall be
				designed and constructed in accordance with AF & PA SDPWS.
2306.2.4
Gypsum board diaphragm
				ceilings.
Gypsum board diaphragm ceilings shall be in accordance with
				Section 2508.5.