Code of Massachusetts Regulations › 780 CMR - STATE BOARD OF BUILDING REGULATIONS AND STANDARDS › Chapter 23 - Wood › Section 2308 - CONVENTIONAL LIGHT-FRAME CONSTRUCTION › Subsection 2308.8 - Floor joists

Current through Register 1525, July 5, 2024
Spans for floor joists shall be in accordance with Table
				  2308.8(1) or 2308.8(2). For other grades and or species, refer to the
AF & PA Span Tables for Joists and Rafters
.
2308.8.1
Bearing.
Except where
				supported on a 1-inch by 4-inch (25.4 mm by 102 mm) ribbon strip and nailed to
				the adjoining stud, the ends of each joist shall not have less than
				11/2 inches (38 mm) of
				bearing on wood or metal, or less than 3 inches (76 mm) on masonry.
TABLE 2308.8(1) FLOOR JOIST SPANS FOR COMMON LUMBER
				  SPECIES (Residential Sleeping Areas, Live Load = 30 pounds per square foot,
L
/[Delta] = 360)
JOIST SPACING
(inches)
SPECIES AND
							 GRADE
DEAD LOAD = 10 psf
DEAD LOAD = 20 psf
2 x 6
2 x 8
2 x 10
2 x 12
2 x 6
2 x 8
2 x 10
2 x 12
Maximum floor joist
							 spans
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
12
Douglas Fir-Larch
SS
12-6
16-6
21-0
25-7
12-6
16-6
21-0
25-7
Douglas Fir-Larch
#1
12-0
15-10
20-3
24-8
12-0
15-7
19-0
22-0
Douglas Fir-Larch
#2
11-10
15-7
19-10
23-0
11-6
14-7
17-9
20-7
Douglas Fir-Larch
#3
9-8
12-4
15-0
17-5
8-8
11-0
13-5
15-7
Hem-Fir
SS
11-10
15-7
19-10
24-2
11-10
15-7
19-10
24-2
Hem-Fir
#1
11-7
15-3
19-5
23-7
11-7
15-2
18-6
21-6
Hem-Fir
#2
11-0
14-6
18-6
22-6
11-0
14-4
17-6
20-4
Hem-Fir
#3
9-8
12-4
15-0
17-5
8-8
11-0
13-5
15-7
Southern Pine
SS
12-3
16-2
20-8
25-1
12-3
16-2
20-8
25-1
Southern Pine
#1
12-0
15-10
20-3
24-8
12-0
15-10
20-3
24-8
Southern Pine
#2
11-10
15-7
19-10
24-2
11-10
15-7
18-7
21-9
Southern Pine
#3
10-5
13-3
15-8
18-8
9-4
11-11
14-0
16-8
Spruce-Pine-Fir
SS
11-7
15-3
19-5
23-7
11-7
15-3
19-5
23-7
Spruce-Pine-Fir
#1
11-3
14-11
19-0
23-0
11-3
14-7
17-9
20-7
Spruce-Pine-Fir
#2
11-3
14-11
19-0
23-0
11-3
14-7
17-9
20-7
Spruce-Pine-Fir
#3
9-8
12-4
15-0
17-5
8-8
11-0
13-5
15-7
16
Douglas Fir-Larch
SS
11-4
15-0
19-1
23-3
11-4
15-0
19-1
23-0
Douglas Fir-Larch
#1
10-11
14-5
18-5
21-4
10-8
13-6
16-5
19-1
Douglas Fir-Larch
#2
10-9
14-1
17-2
19-11
9-11
12-7
15-5
17-10
Douglas Fir-Larch
#3
8-5
10-8
13-0
15-1
7-6
9-6
11-8
13-6
Hem-Fir
SS
10-9
14-2
18-0
21-11
10-9
14-2
18-0
21-11
Hem-Fir
#1
10-6
13-10
17-8
20-9
10-4
13-1
16-0
18-7
Hem-Fir
#2
10-0
13-2
16-10
19-8
9-10
12-5
15-2
17-7
Hem-Fir
#3
8-5
10-8
13-0
15-1
7-6
9-6
11-8
13-6
Southern Pine
SS
11-2
14-8
18-9
22-10
11-2
14-8
18-9
22-10
Southern Pine
#1
10-11
14-5
18-5
22-5
10-11
14-5
17-11
21-4
Southern Pine
#2
10-9
14-2
18-0
21-1
10-5
13-6
16-1
18-10
Southern Pine
#3
9-0
11-6
13-7
16-2
8-1
10-3
12-2
14-6
Spruce-Pine-Fir
SS
10-6
13-10
17-8
21-6
10-6
13-10
17-8
21-4
Spruce-Pine-Fir
#1
10-3
13-6
17-2
19-11
9-11
12-7
15-5
17-10
Spruce-Pine-Fir
#2
10-3
13-6
17-2
19-11
9-11
12-7
15-5
17-10
Spruce-Pine-Fir
#3
8-5
10-8
13-0
15-1
7-6
9-6
11-8
13-6
TABLE 2308.8(1)-continued FLOOR JOIST SPANS FOR COMMON
				  LUMBER SPECIES (Residential Sleeping Areas, Live Load = 30 pounds per square
				  foot,
L
/[Delta] = 360)
JOIST SPACING
(inches)
SPECIES AND
							 GRADE
DEAD LOAD = 10 psf
DEAD LOAD = 20 psf
2 x 6
2 x 8
2 x 10
2 x 12
2 x 6
2 x 8
2 x 10
2 x 12
Maximum floor joist
							 spans
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
19.2
Douglas Fir-Larch
SS
10-8
14-1
18-0
21-10
10-8
14-1
18-0
21-0
Douglas Fir-Larch
#1
10-4
13-7
16-9
19-6
9-8
12-4
15-0
17-5
Douglas Fir-Larch
#2
10-1
12-10
15-8
18-3
9-1
11-6
14-1
16-3
Douglas Fir-Larch
#3
7-8
9-9
11-10
13-9
6-10
8-8
10-7
12-4
Hem-Fir
SS
10-1
13-4
17-0
20-8
10-1
13-4
17-0
20-7
Hem-Fir
#1
9-10
13-0
16-4
19-0
9-6
12-0
14-8
17-0
Hem-Fir
#2
9-5
12-5
15-6
17-1
8-11
11-4
13-10
16-1
Hem-Fir
#3
7-8
9-9
11-10
13-9
6-10
8-8
10-7
12-4
Southern Pine
SS
10-6
13-10
17-8
21-6
10-6
13-10
17-8
21-6
Southern Pine
#1
10-4
13-7
17-4
21-1
10-4
13-7
16-4
19-6
Southern Pine
#2
10-1
13-4
16-5
19-3
9-6
12-4
14-8
17-2
Southern Pine
#3
8-3
10-6
12-5
14-9
7-4
9-5
11-1
13-2
Spruce-Pine-Fir
SS
9-10
13-0
16-7
20-2
9-10
13-0
16-7
19-6
Spruce-Pine-Fir
#1
9-8
12-9
15-8
18-3
9-1
11-6
14-1
16-3
Spruce-Pine-Fir
#2
9-8
12-9
15-8
18-3
9-1
11-6
14-1
16-3
Spruce-Pine-Fir
#3
7-8
9-9
11-10
13-9
6-10
8-8
10-7
12-4
24
Douglas Fir-Larch
SS
9-11
13-1
16-8
20-3
9-11
13-1
16-2
18-9
Douglas Fir-Larch
#1
9-7
12-4
15-0
17-5
8-8
11-0
13-5
15-7
Douglas Fir-Larch
#2
9-1
11-6
14-1
16-3
8-1
10-3
12-7
14-7
Douglas Fir-Larch
#3
6-10
8-8
10-7
12-4
6-2
7-9
9-6
11-0
Hem-Fir
SS
9-4
12-4
15-9
19-2
9-4
12-4
15-9
18-5
Hem-Fir
#1
9-2
12-0
14-8
17-0
8-6
10-9
13-1
15-2
Hem-Fir
#2
8-9
11-4
13-10
16-1
8-0
10-2
12-5
14-4
Hem-Fir
#3
6-10
8-8
10-7
12-4
6-2
7-9
9-6
11-0
Southern Pine
SS
9-9
12-10
16-5
19-11
9-9
12-10
16-5
19-11
Southern Pine
#1
9-7
12-7
16-1
19-6
9-7
12-4
14-7
17-5
Southern Pine
#2
9-4
12-4
14-8
17-2
8-6
11-0
13-1
15-5
Southern Pine
#3
7-4
9-5
11-1
13-2
6-7
8-5
9-11
11-10
Spruce-Pine-Fir
SS
9-2
12-1
15-5
18-9
9-2
12-1
15-0
17-5
Spruce-Pine-Fir
#1
8-11
11-6
14-1
16-3
8-1
10-3
12-7
14-7
Spruce-Pine-Fir
#2
8-11
11-6
14-1
16-3
8-1
10-3
12-7
14-7
Spruce-Pine-Fir
#3
6-10
8-8
10-7
12-4
6-2
7-9
9-6
11-0
Check sources for availability of lumber in lengths
							 greater than 20 feet.
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm,
							 1 pound per square foot = 47.8 N/m2.
TABLE 2308.8(2) FLOOR JOIST SPANS FOR COMMON LUMBER
				  SPECIES (Residential Living Areas, Live Load = 40 pounds per square foot,
L
/[Delta] = 360)
JOIST SPACING
(inches)
SPECIES AND
							 GRADE
DEAD LOAD = 10 psf
DEAD LOAD = 20 psf
2 x 6
2 x 8
2 x 10
2 x 12
2 x 6
2 x 8
2 x 10
2 x 12
Maximum floor joist
							 spans
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
12
Douglas Fir-Larch
SS
11-4
15-0
19-1
23-3
11-4
15-0
19-1
23-3
Douglas Fir-Larch
#1
10-11
14-5
18-5
22-0
10-11
14-2
17-4
20-1
Douglas Fir-Larch
#2
10-9
14-2
17-9
20-7
10-6
13-3
16-3
18-10
Douglas Fir-Larch
#3
8-8
11-0
13-5
15-7
7-11
10-0
12-3
14-3
Hem-Fir
SS
10-9
14-2
18-0
21-11
10-9
14-2
18-0
21-11
Hem-Fir
#1
10-6
13-10
17-8
21-6
10-6
13-10
16-11
19-7
Hem-Fir
#2
10-0
13-2
16-10
20-4
10-0
13-1
16-0
18-6
Hem-Fir
#3
8-8
11-0
13-5
15-7
7-11
10-0
12-3
14-3
Southern Pine
SS
11-2
14-8
18-9
22-10
11-2
14-8
18-9
22-10
Southern Pine
#1
10-11
14-5
18-5
22-5
10-11
14-5
18-5
22-5
Southern Pine
#2
10-9
14-2
18-0
21-9
10-9
14-2
16-11
19-10
Southern Pine
#3
9-4
11-11
14-0
16-8
8-6
10-10
12-10
15-3
Spruce-Pine-Fir
SS
10-6
13-10
17-8
21-6
10-6
13-10
17-8
21-6
Spruce-Pine-Fir
#1
10-3
13-6
17-3
20-7
10-3
13-3
16-3
18-10
Spruce-Pine-Fir
#2
10-3
13-6
17-3
20-7
10-3
13-3
16-3
18-10
Spruce-Pine-Fir
#3
8-8
11-0
13-5
15-7
7-11
10-0
12-3
14-3
16
Douglas Fir-Larch
SS
10-4
13-7
17-4
21-1
10-4
13-7
17-4
21-0
Douglas Fir-Larch
#1
9-11
13-1
16-5
19-1
9-8
12-4
15-0
17-5
Douglas Fir-Larch
#2
9-9
12-7
15-5
17-10
9-1
11-6
14-1
16-3
Douglas Fir-Larch
#3
7-6
9-6
11-8
13-6
6-10
8-8
10-7
12-4
Hem-Fir
SS
9-9
12-10
16-5
19-11
9-9
12-10
16-5
19-11
Hem-Fir
#1
9-6
12-7
16-0
18-7
9-6
12-0
14-8
17-0
Hem-Fir
#2
9-1
12-0
15-2
17-7
8-11
11-4
13-10
16-1
Hem-Fir
#3
7-6
9-6
11-8
13-6
6-10
8-8
10-7
12-4
Southern Pine
SS
10-2
13-4
17-0
20-9
10-2
13-4
17-0
20-9
Southern Pine
#1
9-11
13-1
16-9
20-4
9-11
13-1
16-4
19-6
Southern Pine
#2
9-9
12-10
16-1
18-10
9-6
12-4
14-8
17-2
Southern Pine
#3
8-1
10-3
12-2
14-6
7-4
9-5
11-1
13-2
Spruce-Pine-Fir
SS
9-6
12-7
16-0
19-6
9-6
12-7
16-0
19-6
Spruce-Pine-Fir
#1
9-4
12-3
15-5
17-10
9-1
11-6
14-1
16-3
Spruce-Pine-Fir
#2
9-4
12-3
15-5
17-10
9-1
11-6
14-1
16-3
Spruce-Pine-Fir
#3
7-6
9-6
11-8
13-6
6-10
8-8
10-7
12-4
TABLE 2308.8(2)-continued FLOOR JOIST SPANS FOR COMMON
				  LUMBER SPECIES (Residential Living Areas, Live Load = 40 pounds per square
				  foot,
L
/[Delta] = 360)
JOIST SPACING
(inches)
SPECIES AND
							 GRADE
DEAD LOAD = 10 psf
DEAD LOAD = 20 psf
2 x 6
2 x 8
2 x 10
2 x 12
2 x 6
2 x 8
2 x 10
2 x 12
Maximum floor joist
							 spans
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
(ft. - in.)
19.2
Douglas Fir-Larch
SS
9-8
12-10
16-4
19-10
9-8
12-10
16-4
19-2
Douglas Fir-Larch
#1
9-4
12-4
15-0
17-5
8-10
11-3
13-8
15-11
Douglas Fir-Larch
#2
9-1
11-6
14-1
16-3
8-3
10-6
12-10
14-10
Douglas Fir-Larch
#3
6-10
8-8
10-7
12-4
6-3
7-11
9-8
11-3
Hem-Fir
SS
9-2
12-1
15-5
18-9
9-2
12-1
15-5
18-9
Hem-Fir
#1
9-0
11-10
14-8
17-0
8-8
10-11
13-4
15-6
Hem-Fir
#2
8-7
11-3
13-10
16-1
8-2
10-4
12-8
14-8
Hem-Fir
#3
6-10
8-8
10-7
12-4
6-3
7-11
9-8
11-3
Southern Pine
SS
9-6
12-7
16-0
19-6
9-6
12-7
16-0
19-6
Southern Pine
#1
9-4
12-4
15-9
19-2
9-4
12-4
14-11
17-9
Southern Pine
#2
9-2
12 -1
14-8
17-2
8-8
11-3
13-5
15-8
Southern Pine
#3
7-4
9-5
11-1
13-2
6-9
8-7
10-1
12-1
Spruce-Pine-Fir
SS
9-0
11-10
15-1
18-4
9-0
11-10
15-1
17-9
Spruce-Pine-Fir
#1
8-9
11-6
14-1
16-3
8-3
10-6
12-10
14-10
Spruce-Pine-Fir
#2
8-9
11-6
14-1
16-3
8-3
10-6
12-10
14-10
Spruce-Pine-Fir
#3
6-10
8-8
10-7
12-4
6-3
7-11
9-8
11-3
24
Douglas Fir-Larch
SS
9-0
11-11
15-2
18-5
9-0
11-11
14-9
17-1
Douglas Fir-Larch
#1
8-8
11-0
13-5
15-7
7-11
10-0
12-3
14-3
Douglas Fir-Larch
#2
8-1
10-3
12-7
14-7
7-5
9-5
11-6
13-4
Douglas Fir-Larch
#3
6-2
7-9
9-6
11-0
5-7
7-1
8-8
10-1
Hem-Fir
SS
8-6
11-3
14-4
17-5
8-6
11-3
14-4
16-10a
Hem-Fir
#1
8-4
10-9
13-1
15-2
7-9
9-9
11-11
13-10
Hem-Fir
#2
7-11
10-2
12-5
14-4
7-4
9-3
11-4
13-1
Hem-Fir
#3
6-2
7-9
9-6
11-0
5-7
7-1
8-8
10-1
Southern Pine
SS
8-10
11-8
14-11
18-1
8-10
11-8
14-11
18-1
Southern Pine
#1
8-8
11-5
14-7
17-5
8-8
11-3
13-4
15-11
Southern Pine
#2
8-6
11-0
13-1
15-5
7-9
10-0
12-0
14-0
Southern Pine
#3
6-7
8-5
9-11
11-10
6-0
7-8
9-1
10-9
Spruce-Pine-Fir
SS
8-4
11-0
14-0
17-0
8-4
11-0
13-8
15-11
Spruce-Pine-Fir
#1
8-1
10-3
12-7
14-7
7-5
9-5
11-6
13-4
Spruce-Pine-Fir
#2
8-1
10-3
12-7
14-7
7-5
9-5
11-6
13-4
Spruce-Pine-Fir
#3
6-2
7-9
9-6
11-0
5-7
7-1
8-8
10-1
Check sources for availability of lumber in lengths
							 greater than 20 feet.
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm,
							 1 pound per square foot = 47.8 N/m2.
a.
							 End bearing length shall be increased to 2 inches.
2308.8.2
Framing details.
Joists
				shall be supported laterally at the ends and at each support by solid blocking
				except where the ends of the joists are nailed to a header, band or rim joist
				or to an adjoining stud or by other means. Solid blocking shall not be less
				than 2 inches (51mm) in thickness and the full depth of the joist. Notches on
				the ends of joists shall not exceed one-fourth the joist depth. Holes bored in
				joists shall not be within 2 inches (51 mm) of the top or bottom of the joist,
				and the diameter of any such hole shall not exceed one-third the depth of the
				joist. Notches in the top or bottom of joists shall not exceed one-sixth the
				depth and shall not be located in the middle third of the span.
Joist framing from opposite sides of a beam, girder or
				  partition shall be lapped at least 3 inches (76 mm) or the opposing joists
				  shall be tied together in an approved manner.
Joists framing into the side of a wood girder shall be
				  supported by framing anchors or on ledger strips not less than 2 inches by 2
				  inches (51 mm by 51 mm).
2308.8.2.1
Engineered wood products.
Cuts, notches and holes bored in
				trusses, structural composite lumber, structural glue-laminated members or
				I-joists are not permitted except where permitted by the manufacturer's
				recommendations or where the effects of such alterations are specifically
				considered in the design of the member by a
registered design
				professional
.