Maximum Span Calculator
for Wood Joists & Rafters
www.awc.org
Species
Alaska Cedar
Alaska Hemlock
Alaska Spruce
Alaska Yellow Cedar
Aspen
Baldcypress
Beech-Birch-Hickory
Coast Sitka Spruce
Cottonwood
Douglas Fir-Larch
Douglas Fir-Larch (North)
Douglas Fir-South
Eastern Hemlock-Balsam Fir
Eastern Hemlock-Tamarack
Eastern Softwoods
Eastern White Pine
Hem-Fir
Hem-Fir (North)
Mixed Maple
Mixed Oak
Mixed Southern Pine
Northern Red Oak
Northern Species
Northern White Cedar
Red Maple
Red Oak
Redwood
Southern Pine
Spruce-Pine-Fir
Spruce-Pine-Fir (South)
Western Cedars
Western Woods
White Oak
Yellow Cedar
Yellow Poplar
Size
2x4
2x6
2x8
2x10
2x12
Grade
Select Structural
No. 1
No. 2
No. 3
Stud
Construction
Standard
Utility
Member Type
Floor Joists
Ceiling Joists
Rafters (Snow Load)
Rafters (Roof Live-Load)
Deflection Limit
L/720
L/600
L/480
L/360
L/240
L/180
Spacing (in)
12
16
19.2
24
Exterior Exposure
Wet service conditions?
No
Yes
Incised lumber?
No
Yes
Live Load (psf)
30
40
50
60
70
80
90
100
Dead Load (psf)
5
7
10
15
20
The
Span Calculator for Wood Joists and Rafters (Span Calc)
is available for the
iPhone
.
