These span tables (Table 15, Table
16, Table 17, and Table
18) are intended as guidelines to provide the user with
an idea of the maximum spans in feet and inches for various
wood products with floor loads common in raised floor systems.
These spans were determined in accordance with appropriate standards,
such as the National Design Specification® (NDS®)
for Wood Construction published by the American Forest &
Paper Association and the National Design Specification for
Metal Plate Connected Wood Truss Construction published
by the Truss Plate Institute. They are based on uniform, gravity
loads only, and assume dry-service conditions. For more complete
span table information, refer to Maximum
Spans for Joists and Rafters, www.awc.org,
or www.woodtruss.com.
Table
15 Floor Joists — Solid-Sawn Southern Pine Lumber
40 psf live load, 10 psf dead load,
ℓ/360 deflection
10 psf dead load top chord, 5 psf
deal load bottom chord
Depth inches
Spacing inches on center
Grade
SS/No.1 DNS feet-inches
No.1 feet-inches
No.2 feet-inches
12
24
16-
11
16-
8
16-
1
14
24
19-
2
18-
11
17-
11
16
24
27-
6
21-
2
19-
2
Source: Wood Truss Council of
America (www.woodtruss.com).
Assumes bottom-chord bearing. SS = Select Structural. DNS =
Dense.
Table
18 Floor Trusses with Southern Pine Lumber
50 psf live load — Commercial
15 psf dead load top chord, 10 psf
deal load bottom chord
Depth inches
Spacing inches on center
Grade
SS feet-inches
No.1 feet-inches
No.2 feet-inches
16
24
24-
3
19-
1
16-
3
18
24
27-
0
21-
5
17-
10
20
24
29-
6
23-
3
19-
8
Source: Wood Truss Council of
America (www.woodtruss.com).
Assumes bottom-chord bearing. SS = Select Structural. DNS =
Dense. Table 18 includes a 20 pound per square foot (psf) partition
load and a 2000 pound concentrated load per the 2000 International
Building Code, sections 1607.5 and 1607.1 respectively.
