Page 422 - 2018_IRC

ROOF-CEILING CONSTRUCTION

TABLE R802.4.1(7)
RAFTER SPANS FOR COMMON LUMBER SPECIES
(Ground snow load = 70 psf, ceiling not attached to rafters, L/∆ = 180)
DEAD LOAD = 10 psf DEAD LOAD = 20 psf
RAFTER 2 × 4 2 × 6 2 × 8 2 × 10 2 × 12 2 × 4 2 × 6 2 × 8 2 × 10 2 × 12
SPACING SPECIES AND GRADE Maximum Rafter Spans a
(inches)
(feet- (feet- (feet- (feet- (feet- (feet- (feet- (feet- (feet- (feet-
inches) inches) inches) inches) inches) inches) inches) inches) inches) inches)
Douglas fir-larch SS 7-7 11-10 15-8 19-9 22-10 7-7 11-10 15-3 18-7 21-7
Douglas fir-larch #1 7-1 10-5 13-2 16-1 18-8 6-8 9-10 12-5 15-2 17-7
Douglas fir-larch #2 6-9 9-10 12-6 15-3 17-9 6-4 9-4 11-9 14-5 16-8
Douglas fir-larch #3 5-2 7-7 9-7 11-8 13-6 4-10 7-1 9-0 11-0 12-9
Hem-fir SS 7-2 11-3 14-9 18-10 22-1 7-2 11-3 14-8 18-0 20-10
Hem #1 7-0 10-3 13-0 15-11 18-5 6-7 9-8 12-3 15-0 17-5
Hem #2 6-7 9-7 12-2 14-10 17-3 6-2 9-1 11-5 14-0 16-3
Hem-fir #3 5-0 7-4 9-4 11-5 13-2 4-9 6-11 8-9 10-9 12-5
12
Southern pine SS 7-5 11-8 15-4 19-7 23-7 7-5 11-8 15-4 18-10 22-3
Southern pine #1 7-1 10-7 13-5 15-9 18-8 6-9 10-0 12-8 14-10 17-7
Southern pine #2 6-1 9-2 11-7 13-9 16-2 5-9 8-7 10-11 12-11 15-3
Southern pine #3 4-8 6-11 8-9 10-7 12-6 4-5 6-6 8-3 10-0 11-10
Spruce-pine-fir SS 7-0 11-0 14-6 18-0 20-11 7-0 11-0 13-11 17-0 19-8
Spruce-pine #1 6-8 9-9 12-4 15-1 17-6 6-3 9-2 11-8 14-2 16-6
Spruce-pine #2 6-8 9-9 12-4 15-1 17-6 6-3 9-2 11-8 14-2 16-6
Spruce-pine-fir #3 5-0 7-4 9-4 11-5 13-2 4-9 6-11 8-9 10-9 12-5
Douglas fir-larch SS 6-10 10-9 14-0 17-1 19-10 6-10 10-5 13-2 16-1 18-8
Douglas fir-larch #1 6-2 9-0 11-5 13-11 16-2 5-10 8-6 10-9 13-2 15-3
Douglas fir-larch #2 5-10 8-7 10-10 13-3 15-4 5-6 8-1 10-3 12-6 14-6
Douglas fir-larch #3 4-6 6-6 8-3 10-1 11-9 4-3 6-2 7-10 9-6 11-1
Hem SS 6-6 10-2 13-5 16-6 19-2 6-6 10-1 12-9 15-7 18-0
Hem-fir #1 6-1 8-11 11-3 13-9 16-0 5-9 8-5 10-8 13-0 15-1
Hem #2 5-8 8-4 10-6 12-10 14-11 5-4 7-10 9-11 12-1 14-1
Hem #3 4-4 6-4 8-1 9-10 11-5 4-1 6-0 7-7 9-4 10-9
16
Southern pine SS 6-9 10-7 14-0 17-4 20-5 6-9 10-7 13-9 16-4 19-3
Southern pine #1 6-2 9-2 11-8 13-8 16-2 5-10 8-8 11-0 12-10 15-3
Southern pine #2 5-3 7-11 10-0 11-11 14-0 5-0 7-5 9-5 11-3 13-2
Southern pine #3 4-1 6-0 7-7 9-2 10-10 3-10 5-8 7-1 8-8 10-3
Spruce-pine-fir SS 6-4 10-0 12-9 15-7 18-1 6-4 9-6 12-0 14-8 17-1
Spruce-pine #1 5-9 8-5 10-8 13-1 15-2 5-5 7-11 10-1 12-4 14-3
Spruce-pine #2 5-9 8-5 10-8 13-1 15-2 5-5 7-11 10-1 12-4 14-3
Spruce-pine #3 4-4 6-4 8-1 9-10 11-5 4-1 6-0 7-7 9-4 10-9
Douglas fir-larch SS 6-6 10-1 12-9 15-7 18-1 6-6 9-6 12-0 14-8 17-1
Douglas fir-larch #1 5-7 8-3 10-5 12-9 14-9 5-4 7-9 9-10 12-0 13-11
Douglas fir-larch #2 5-4 7-10 9-11 12-1 14-0 5-0 7-4 9-4 11-5 13-2
Douglas fir-larch #3 4-1 6-0 7-7 9-3 10-8 3-10 5-7 7-1 8-8 10-1
19.2
Hem SS 6-1 9-7 12-4 15-1 17-4 6-1 9-2 11-8 14-2 15-5
Hem #1 5-7 8-2 10-3 12-7 14-7 5-3 7-8 9-8 11-10 13-9
Hem #2 5-2 7-7 9-7 11-9 13-7 4-11 7-2 9-1 11-1 12-10
Hem #3 4-0 5-10 7-4 9-0 10-5 3-9 5-6 6-11 8-6 9-10
(continued)

2018 INTERNATIONAL RESIDENTIAL CODE ® 397
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