Span Options Calculator
for Joists & Rafters
Species
Required Horizontal Span
ft.
in.
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
Ctrl-Click to select multiple species
Member Type
Floor Joist
Ceiling Joist
Rafter (Snow Load)
Rafter (Roof Live-Load)
Deflection Limit
L/720
L/600
L/480
L/360
L/240
L/180
Spacing (in)
12
16
19.2
24
Live Load (psf)
30
40
50
60
70
80
90
100
Dead Load (psf)
5
7
10
15
20
Exterior Exposure
Wet service conditions?
No
Yes
Incised lumber?
No
Yes
