The framing details required in this section apply to roofs having a slope of not less than three units vertical in 12 units horizontal (25-percent slope). Where the roof slope is less than three units vertical in 12 units horizontal (25-percent slope), members supporting rafters and ceiling joists such as ridge board, hips and valleys shall be designed as beams.
Spans for ceiling joists shall be in accordance with Table 2308.7.1(1) or 2308.7.1(2). For other grades and species, and other loading conditions, refer to the AWC STJR.
TABLE 2308.7.1(1) CEILING JOIST SPANS FOR COMMON LUMBER SPECIES (Uninhabitable Attics Without Storage, Live Load = 10 psf, L/Δ = 240)
(continued)
TABLE 2308.7.1(1)‒continued CEILING JOIST SPANS FOR COMMON LUMBER SPECIES (Uninhabitable Attics Without Storage, Live Load = 10 psf, L/Δ = 240)
TABLE 2308.7.1(2) CEILING JOIST SPANS FOR COMMON LUMBER SPECIES (Uninhabitable Attics With Limited Storage, Live Load = 20 psf, L/Δ= 240)
(continued)
TABLE 2308.7.1(2)‒continued CEILING JOIST SPANS FOR COMMON LUMBER SPECIES (Uninhabitable Attics With Limited Storage, Live Load = 20 psf, L/Δ = 240)
TABLE 2308.7.1(1) CEILING JOIST SPANS FOR COMMON LUMBER SPECIES (Uninhabitable Attics Without Storage, Live Load = 10 psf, L/Δ = 240)
| CEILING JOIST SPACING (inches) | SPECIES AND GRADE | DEAD LOAD = 5 psf | ||||
| 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | |||
| Maximum ceiling joist spans | ||||||
| (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | |||
| 12 | Douglas Fir-Larch | SS | 13-2 | 20-8 | Note a | Note a |
| Douglas Fir-Larch | #1 | 12-8 | 19-11 | Note a | Note a | |
| Douglas Fir-Larch | #2 | 12-5 | 19-6 | 25-8 | Note a | |
| Douglas Fir-Larch | #3 | 10-10 | 15-10 | 20-1 | 24-6 | |
| Hem-Fir | SS | 12-5 | 19-6 | 25-8 | Note a | |
| Hem-Fir | #1 | 12-2 | 19-1 | 25-2 | Note a | |
| Hem-Fir | #2 | 11-7 | 18-2 | 24-0 | Note a | |
| Hem-Fir | #3 | 10-10 | 15-10 | 20-1 | 24-6 | |
| Southern Pine | SS | 12-11 | 20-3 | Note a | Note a | |
| Southern Pine | #1 | 12-5 | 19-6 | 25-8 | Note a | |
| Southern Pine | #2 | 11-10 | 18-8 | 24-7 | Note a | |
| Southern Pine | #3 | 10-1 | 14-11 | 18-9 | 22-9 | |
| Spruce-Pine-Fir | SS | 12-2 | 19-1 | 25-2 | Note a | |
| Spruce-Pine-Fir | #1 | 11-10 | 18-8 | 24-7 | Note a | |
| Spruce-Pine-Fir | #2 | 11-10 | 18-8 | 24-7 | Note a | |
| Spruce-Pine-Fir | #3 | 10-10 | 15-10 | 20-1 | 24-6 | |
| 16 | Douglas Fir-Larch | SS | 11-11 | 18-9 | 24-8 | Note a |
| Douglas Fir-Larch | #1 | 11-6 | 18-1 | 23-10 | Note a | |
| Douglas Fir-Larch | #2 | 11-3 | 17-8 | 23-0 | Note a | |
| Douglas Fir-Larch | #3 | 9-5 | 13-9 | 17-5 | 21-3 | |
| Hem-Fir | SS | 11-3 | 17-8 | 23-4 | Note a | |
| Hem-Fir | #1 | 11-0 | 17-4 | 22-10 | Note a | |
| Hem-Fir | #2 | 10-6 | 16-6 | 21-9 | Note a | |
| Hem-Fir | #3 | 9-5 | 13-9 | 17-5 | 21-3 | |
| Southern Pine | SS | 11-9 | 18-5 | 24-3 | Note a | |
| Southern Pine | #1 | 11-3 | 17-8 | 23-4 | Note a | |
| Southern Pine | #2 | 10-9 | 16-11 | 21-7 | 25-7 | |
| Southern Pine | #3 | 8-9 | 12-11 | 16-3 | 19-9 | |
| Spruce-Pine-Fir | SS | 11-0 | 17-4 | 22-10 | Note a | |
| Spruce-Pine-Fir | #1 | 10-9 | 16-11 | 22-4 | Note a | |
| Spruce-Pine-Fir | #2 | 10-9 | 16-11 | 22-4 | Note a | |
| Spruce-Pine-Fir | #3 | 9-5 | 13-9 | 17-5 | 21-3 | |
(continued)
TABLE 2308.7.1(1)‒continued CEILING JOIST SPANS FOR COMMON LUMBER SPECIES (Uninhabitable Attics Without Storage, Live Load = 10 psf, L/Δ = 240)
| CEILING JOIST SPACING (inches) | SPECIES AND GRADE | DEAD LOAD = 5 psf | ||||
| 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | |||
| Maximum ceiling joist spans | ||||||
| (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | |||
| 19.2 | Douglas Fir-Larch | SS | 11-3 | 17-8 | 23-3 | Note a |
| Douglas Fir-Larch | #1 | 10-10 | 17-0 | 22-5 | Note a | |
| Douglas Fir-Larch | #2 | 10-7 | 16-7 | 21-0 | 25-8 | |
| Douglas Fir-Larch | #3 | 8-7 | 12-6 | 15-10 | 19-5 | |
| Hem-Fir | SS | 10-7 | 16-8 | 21-11 | Note a | |
| Hem-Fir | #1 | 10-4 | 16-4 | 21-6 | Note a | |
| Hem-Fir | #2 | 9-11 | 15-7 | 20-6 | 25-3 | |
| Hem-Fir | #3 | 8-7 | 12-6 | 15-10 | 19-5 | |
| Southern Pine | SS | 11-0 | 17-4 | 22-10 | Note a | |
| Southern Pine | #1 | 10-7 | 16-8 | 22-0 | Note a | |
| Southern Pine | #2 | 10-2 | 15-7 | 19-8 | 23-5 | |
| Southern Pine | #3 | 8-0 | 11-9 | 14-10 | 18-0 | |
| Spruce-Pine-Fir | SS | 10-4 | 16-4 | 21-6 | Note a | |
| Spruce-Pine-Fir | #1 | 10-2 | 15-11 | 21-0 | 25-8 | |
| Spruce-Pine-Fir | #2 | 10-2 | 15-11 | 21-0 | 25-8 | |
| Spruce-Pine-Fir | #3 | 8-7 | 12-6 | 15-10 | 19-5 | |
| 24 | Douglas Fir-Larch | SS | 10-5 | 16-4 | 21-7 | Note a |
| Douglas Fir-Larch | #1 | 10-0 | 15-9 | 20-1 | 24-6 | |
| Douglas Fir-Larch | #2 | 9-10 | 14-10 | 18-9 | 22-11 | |
| Douglas Fir-Larch | #3 | 7-8 | 11-2 | 14-2 | 17-4 | |
| Hem-Fir | SS | 9-10 | 15-6 | 20-5 | Note a | |
| Hem-Fir | #1 | 9-8 | 15-2 | 19-7 | 23-11 | |
| Hem-Fir | #2 | 9-2 | 14-5 | 18-6 | 22-7 | |
| Hem-Fir | #3 | 7-8 | 11-2 | 14-2 | 17-4 | |
| Southern Pine | SS | 10-3 | 16-1 | 21-2 | Note a | |
| Southern Pine | #1 | 9-10 | 15-6 | 20-5 | 24-0 | |
| Southern Pine | #2 | 9-3 | 13-11 | 17-7 | 20-11 | |
| Southern Pine | #3 | 7-2 | 10-6 | 13-3 | 16-1 | |
| Spruce-Pine-Fir | SS | 9-8 | 15-2 | 19-11 | 25-5 | |
| Spruce-Pine-Fir | #1 | 9-5 | 14-9 | 18-9 | 22-11 | |
| Spruce-Pine-Fir | #2 | 9-5 | 14-9 | 18-9 | 22-11 | |
| Spruce-Pine-Fir | #3 | 7-8 | 11-2 | 14-2 | 17-4 | |
| 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 = 0.0479 kPa. |
| a. Span exceeds 26 feet in length. |
TABLE 2308.7.1(2) CEILING JOIST SPANS FOR COMMON LUMBER SPECIES (Uninhabitable Attics With Limited Storage, Live Load = 20 psf, L/Δ= 240)
| CEILING JOIST SPACING (inches) | SPECIES AND GRADE | DEAD LOAD = 10 psf | ||||
| 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | |||
| Maximum ceiling joist spans | ||||||
| (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | |||
| 12 | Douglas Fir-Larch | SS | 10-5 | 16-4 | 21-7 | Note a |
| Douglas Fir-Larch | #1 | 10-0 | 15-9 | 20-1 | 24-6 | |
| Douglas Fir-Larch | #2 | 9-10 | 14-10 | 18-9 | 22-11 | |
| Douglas Fir-Larch | #3 | 7-8 | 11-2 | 14-2 | 17-4 | |
| Hem-Fir | SS | 9-10 | 15-6 | 20-5 | Note a | |
| Hem-Fir | #1 | 9-8 | 15-2 | 19-7 | 23-11 | |
| Hem-Fir | #2 | 9-2 | 14-5 | 18-6 | 22-7 | |
| Hem-Fir | #3 | 7-8 | 11-2 | 14-2 | 17-4 | |
| Southern Pine | SS | 10-3 | 16-1 | 21-2 | Note a | |
| Southern Pine | #1 | 9-10 | 15-6 | 20-5 | 24-0 | |
| Southern Pine | #2 | 9-3 | 13-11 | 17-7 | 20-11 | |
| Southern Pine | #3 | 7-2 | 10-6 | 13-3 | 16-1 | |
| Spruce-Pine-Fir | SS | 9-8 | 15-2 | 19-11 | 25-5 | |
| Spruce-Pine-Fir | #1 | 9-5 | 14-9 | 18-9 | 22-11 | |
| Spruce-Pine-Fir | #2 | 9-5 | 14-9 | 18-9 | 22-11 | |
| Spruce-Pine-Fir | #3 | 7-8 | 11-2 | 14-2 | 17-4 | |
| 16 | Douglas Fir-Larch | SS | 9-6 | 14-11 | 19-7 | 25-0 |
| Douglas Fir-Larch | #1 | 9-1 | 13-9 | 17-5 | 21-3 | |
| Douglas Fir-Larch | #2 | 8-9 | 12-10 | 16-3 | 19-10 | |
| Douglas Fir-Larch | #3 | 6-8 | 9-8 | 12-4 | 15-0 | |
| Hem-Fir | SS | 8-11 | 14-1 | 18-6 | 23-8 | |
| Hem-Fir | #1 | 8-9 | 13-5 | 16-10 | 20-8 | |
| Hem-Fir | #2 | 8-4 | 12-8 | 16-0 | 19-7 | |
| Hem-Fir | #3 | 6-8 | 9-8 | 12-4 | 15-0 | |
| Southern Pine | SS | 9-4 | 14-7 | 19-3 | 24-7 | |
| Southern Pine | #1 | 8-11 | 14-0 | 17-9 | 20-9 | |
| Southern Pine | #2 | 8-0 | 12-0 | 15-3 | 18-1 | |
| Southern Pine | #3 | 6-2 | 9-2 | 11-6 | 14-0 | |
| Spruce-Pine-Fir | SS | 8-9 | 13-9 | 18-1 | 23-1 | |
| Spruce-Pine-Fir | #1 | 8-7 | 12-10 | 16-3 | 19-10 | |
| Spruce-Pine-Fir | #2 | 8-7 | 12-10 | 16-3 | 19-10 | |
| Spruce-Pine-Fir | #3 | 6-8 | 9-8 | 12-4 | 15-0 | |
(continued)
TABLE 2308.7.1(2)‒continued CEILING JOIST SPANS FOR COMMON LUMBER SPECIES (Uninhabitable Attics With Limited Storage, Live Load = 20 psf, L/Δ = 240)
| CEILING JOIST SPACING (inches) | SPECIES AND GRADE | DEAD LOAD = 10 psf | ||||
| 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | |||
| Maximum ceiling joist spans | ||||||
| (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | |||
| 19.2 | Douglas Fir-Larch | SS | 8-11 | 14-0 | 18-5 | 23-4 |
| Douglas Fir-Larch | #1 | 8-7 | 12-6 | 15-10 | 19-5 | |
| Douglas Fir-Larch | #2 | 8-0 | 11-9 | 14-10 | 18-2 | |
| Douglas Fir-Larch | #3 | 6-1 | 8-10 | 11-3 | 13-8 | |
| Hem-Fir | SS | 8-5 | 13-3 | 17-5 | 22-3 | |
| Hem-Fir | #1 | 8-3 | 12-3 | 15-6 | 18-11 | |
| Hem-Fir | #2 | 7-10 | 11-7 | 14-8 | 17-10 | |
| Hem-Fir | #3 | 6-1 | 8-10 | 11-3 | 13-8 | |
| Southern Pine | SS | 8-9 | 13-9 | 18-2 | 23-1 | |
| Southern Pine | #1 | 8-5 | 12-9 | 16-2 | 18-11 | |
| Southern Pine | #2 | 7-4 | 11-0 | 13-11 | 16-6 | |
| Southern Pine | #3 | 5-8 | 8-4 | 10-6 | 12-9 | |
| Spruce-Pine-Fir | SS | 8-3 | 12-11 | 17-1 | 21-8 | |
| Spruce-Pine-Fir | #1 | 8-0 | 11-9 | 14-10 | 18-2 | |
| Spruce-Pine-Fir | #2 | 8-0 | 11-9 | 14-10 | 18-2 | |
| Spruce-Pine-Fir | #3 | 6-1 | 8-10 | 11-3 | 13-8 | |
| 24 | Douglas Fir-Larch | SS | 8-3 | 13-0 | 17-1 | 20-11 |
| Douglas Fir-Larch | #1 | 7-8 | 11-2 | 14-2 | 17-4 | |
| Douglas Fir-Larch | #2 | 7-2 | 10-6 | 13-3 | 16-3 | |
| Douglas Fir-Larch | #3 | 5-5 | 7-11 | 10-0 | 12-3 | |
| Hem-Fir | SS | 7-10 | 12-3 | 16-2 | 20-6 | |
| Hem-Fir | #1 | 7-6 | 10-11 | 13-10 | 16-11 | |
| Hem-Fir | #2 | 7-1 | 10-4 | 13-1 | 16-0 | |
| Hem-Fir | #3 | 5-5 | 7-11 | 10-0 | 12-3 | |
| Southern Pine | SS | 8-1 | 12-9 | 16-10 | 21-6 | |
| Southern Pine | #1 | 7-8 | 11-5 | 14-6 | 16-11 | |
| Southern Pine | #2 | 6-7 | 9-10 | 12-6 | 14-9 | |
| Southern Pine | #3 | 5-1 | 7-5 | 9-5 | 11-5 | |
| Spruce-Pine-Fir | SS | 7-8 | 12-0 | 15-10 | 19-5 | |
| Spruce-Pine-Fir | #1 | 7-2 | 10-6 | 13-3 | 16-3 | |
| Spruce-Pine-Fir | #2 | 7-2 | 10-6 | 13-3 | 16-3 | |
| Spruce-Pine-Fir | #3 | 5-5 | 7-11 | 10-0 | 12-3 | |
| 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 = 0.0479 kPa. |
| a. Span exceeds 26 feet in length. |
Spans for rafters shall be in accordance with Table 2308.7.2(1), 2308.7.2(2), 2308.7.2(3), 2308.7.2(4), 2308.7.2(5) or 2308.7.2(6). For other grades and species and other loading conditions, refer to the AWC STJR. The span of each rafter shall be measured along the horizontal projection of the rafter.
TABLE 2308.7.2(1) RAFTER SPANS FOR COMMON LUMBER SPECIES (Roof Live Load = 20 psf, Ceiling Not Attached to Rafters, L/Δ = 180)
(continued)
TABLE 2308.7.2(1)‒continued RAFTER SPANS FOR COMMON LUMBER SPECIES (Roof Live Load = 20 psf, Ceiling Not Attached to Rafters, L/Δ = 180)
where:
TABLE 2308.7.2(2) RAFTER SPANS FOR COMMON LUMBER SPECIES (Roof Live Load = 20 psf, Ceiling Attached to Rafters, L/Δ = 240)
(continued)
TABLE 2308.7.2(2)‒continued RAFTER SPANS FOR COMMON LUMBER SPECIES (Roof Live Load = 20 psf, Ceiling Attached to Rafters, L/Δ = 240)
where:
TABLE 2308.7.2(3) RAFTER SPANS FOR COMMON LUMBER SPECIES (Ground Snow Load = 30 psf, Ceiling Not Attached to Rafters, L/Δ = 180)
(continued)
TABLE 2308.7.2(3)‒continued RAFTER SPANS FOR COMMON LUMBER SPECIES (Ground Snow Load = 30 psf, Ceiling Not Attached to Rafters, L/Δ = 180)
where:
TABLE 2308.7.2(4) RAFTER SPANS FOR COMMON LUMBER SPECIES (Ground Snow Load = 50 psf, Ceiling Not Attached to Rafters, L/Δ = 180)
(continued)
TABLE 2308.7.2(4) RAFTER SPANS FOR COMMON LUMBER SPECIES (Ground Snow Load = 50 psf, Ceiling Not Attached to Rafters, L/Δ = 180)
where:
TABLE 2308.7.2(5) RAFTER SPANS FOR COMMON LUMBER SPECIES (Ground Snow Load = 30 psf, Ceiling Attached to Rafters, L/Δ= 240)
(continued)
TABLE 2308.7.2(5)‒continued RAFTER SPANS FOR COMMON LUMBER SPECIES (Ground Snow Load = 30 psf, Ceiling Attached to Rafters, L/Δ = 240)
where:
TABLE 2308.7.2(6) RAFTER SPANS FOR COMMON LUMBER SPECIES (Ground Snow Load = 50 psf, Ceiling Attached to Rafters, L/Δ = 240)
(continued)
TABLE 2308.7.2(6)‒continued RAFTER SPANS FOR COMMON LUMBER SPECIES (Ground Snow Load = 50 psf, Ceiling Attached to Rafters, L/Δ = 240)
where:
TABLE 2308.7.2(1) RAFTER SPANS FOR COMMON LUMBER SPECIES (Roof Live Load = 20 psf, Ceiling Not Attached to Rafters, L/Δ = 180)
| RAFTER SPACING (inches) | SPECIES AND GRADE | DEAD LOAD = 10 psf | DEAD LOAD = 20 psf | |||||||||
| 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | |||
| Maximum rafter spansa | ||||||||||||
| (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | |||
| 12 | Douglas Fir-Larch | SS | 11-6 | 18-0 | 23-9 | Note b | Note b | 11-6 | 18-0 | 23-5 | Note b | Note b |
| Douglas Fir-Larch | #1 | 11-1 | 17-4 | 22-5 | Note b | Note b | 10-6 | 15-4 | 19-5 | 23-9 | Note b | |
| Douglas Fir-Larch | #2 | 10-10 | 16-7 | 21-0 | 25-8 | Note b | 9-10 | 14-4 | 18-2 | 22-3 | 25-9 | |
| Douglas Fir-Larch | #3 | 8-7 | 12-6 | 15-10 | 19-5 | 22-6 | 7-5 | 10-10 | 13-9 | 16-9 | 19-6 | |
| Hem-Fir | SS | 10-10 | 17-0 | 22-5 | Note b | Note b | 10-10 | 17-0 | 22-5 | Note b | Note b | |
| Hem-Fir | #1 | 10 -7 | 16-8 | 21-10 | Note b | Note b | 10-3 | 14-11 | 18-11 | 23-2 | Note b | |
| Hem-Fir | #2 | 10-1 | 15-11 | 20-8 | 25-3 | Note b | 9-8 | 14-2 | 17-11 | 21-11 | 25-5 | |
| Hem-Fir | #3 | 8-7 | 12-6 | 15-10 | 19-5 | 22-6 | 7-5 | 10-10 | 13-9 | 16-9 | 19-6 | |
| Southern Pine | SS | 11-3 | 17-8 | 23-4 | Note b | Note b | 11-3 | 17-8 | 23-4 | Note b | Note b | |
| Southern Pine | #1 | 10-10 | 17-0 | 22-5 | 26-0 | 26-0 | 10-6 | 15-8 | 19-10 | 23-2 | Note b | |
| Southern Pine | #2 | 10-4 | 15-7 | 19-8 | 23-5 | 26-0 | 9-0 | 13-6 | 17-1 | 20-3 | 23-10 | |
| Southern Pine | #3 | 8-0 | 11-9 | 14-10 | 18-0 | 21-4 | 6-11 | 10-2 | 12-10 | 15-7 | 18-6 | |
| Spruce-Pine-Fir | SS | 10-7 | 16-8 | 21-11 | Note b | Note b | 10-7 | 16-8 | 21-9 | Note b | Note b | |
| Spruce-Pine-Fir | #1 | 10-4 | 16-3 | 21-0 | 25-8 | Note b | 9-10 | 14-4 | 18-2 | 22-3 | 25-9 | |
| Spruce-Pine-Fir | #2 | 10-4 | 16-3 | 21-0 | 25-8 | Note b | 9-10 | 14-4 | 18-2 | 22-3 | 25-9 | |
| Spruce-Pine-Fir | #3 | 8-7 | 12-6 | 15-10 | 19-5 | 22-6 | 7-5 | 10-10 | 13-9 | 16-9 | 19-6 | |
| 16 | Douglas Fir-Larch | SS | 10-5 | 16-4 | 21-7 | Note b | Note b | 10-5 | 16-0 | 20-3 | 24-9 | Note b |
| Douglas Fir-Larch | #1 | 10-0 | 15-4 | 19-5 | 23-9 | Note b | 9-1 | 13-3 | 16-10 | 20-7 | 23-10 | |
| Douglas Fir-Larch | #2 | 9-10 | 14-4 | 18-2 | 22-3 | 25-9 | 8-6 | 12-5 | 15-9 | 19-3 | 22-4 | |
| Douglas Fir-Larch | #3 | 7-5 | 10-10 | 13-9 | 16-9 | 19-6 | 6-5 | 9-5 | 11-11 | 14-6 | 16-10 | |
| Hem-Fir | SS | 9-10 | 15-6 | 20-5 | Note b | Note b | 9-10 | 15-6 | 19-11 | 24-4 | Note b | |
| Hem-Fir | #1 | 9-8 | 14-11 | 18-11 | 23-2 | Note b | 8-10 | 12-11 | 16-5 | 20-0 | 23-3 | |
| Hem-Fir | #2 | 9-2 | 14-2 | 17-11 | 21-11 | 25-5 | 8-5 | 12-3 | 15-6 | 18-11 | 22-0 | |
| Hem-Fir | #3 | 7-5 | 10-10 | 13-9 | 16-9 | 19-6 | 6-5 | 9-5 | 11-11 | 14-6 | 16-10 | |
| Southern Pine | SS | 10-3 | 16-1 | 21-2 | Note b | Note b | 10-3 | 16-1 | 21-2 | 25-7 | Note b | |
| Southern Pine | #1 | 9-10 | 15-6 | 19-10 | 23-2 | 26-0 | 9-1 | 13-7 | 17-2 | 20-1 | 23-10 | |
| Southern Pine | #2 | 9-0 | 13-6 | 17-1 | 20-3 | 23-10 | 7-9 | 11-8 | 14-9 | 17-6 | 20-8 | |
| Southern Pine | #3 | 6-11 | 10-2 | 12-10 | 15-7 | 18-6 | 6-0 | 8-10 | 11-2 | 13-6 | 16-0 | |
| Spruce-Pine-Fir | SS | 9-8 | 15-2 | 19-11 | 25-5 | Note b | 9-8 | 14-10 | 18-10 | 23-0 | Note b | |
| Spruce-Pine-Fir | #1 | 9-5 | 14-4 | 18-2 | 22-3 | 25-9 | 8-6 | 12-5 | 15-9 | 19-3 | 22-4 | |
| Spruce-Pine-Fir | #2 | 9-5 | 14-4 | 18-2 | 22-3 | 25-9 | 8-6 | 12-5 | 15-9 | 19-3 | 22-4 | |
| Spruce-Pine-Fir | #3 | 7-5 | 10-10 | 13-9 | 16-9 | 19-6 | 6-5 | 9-5 | 11-11 | 14-6 | 16-10 | |
| 19.2 | Douglas Fir-Larch | SS | 9-10 | 15-5 | 20-4 | 25-11 | Note b | 9-10 | 14-7 | 18-6 | 22-7 | Note b |
| Douglas Fir-Larch | #1 | 9-5 | 14-0 | 17-9 | 21-8 | 25-2 | 8-4 | 12-2 | 15-4 | 18-9 | 21-9 | |
| Douglas Fir-Larch | #2 | 8-11 | 13-1 | 16-7 | 20-3 | 23-6 | 7-9 | 11-4 | 14-4 | 17-7 | 20-4 | |
| Douglas Fir-Larch | #3 | 6-9 | 9-11 | 12-7 | 15-4 | 17-9 | 5-10 | 8-7 | 10-10 | 13-3 | 15-5 | |
| Hem-Fir | SS | 9-3 | 14-7 | 19-2 | 24-6 | Note b | 9-3 | 14-4 | 18-2 | 22-3 | 25-9 | |
| Hem-Fir | #1 | 9-1 | 13-8 | 17-4 | 21-1 | 24-6 | 8-1 | 11-10 | 15-0 | 18-4 | 21-3 | |
| Hem-Fir | #2 | 8-8 | 12-11 | 16-4 | 20-0 | 23-2 | 7-8 | 11-2 | 14-2 | 17-4 | 20-1 | |
| Hem-Fir | #3 | 6-9 | 9-11 | 12-7 | 15-4 | 17-9 | 5-10 | 8-7 | 10-10 | 13-3 | 15-5 | |
| Southern Pine | SS | 9-8 | 15-2 | 19-11 | 25-5 | Note b | 9-8 | 15-2 | 19-7 | 23-4 | Note b | |
| Southern Pine | #1 | 9-3 | 14-3 | 18-1 | 21-2 | 25-2 | 8-4 | 12-4 | 15-8 | 18-4 | 21-9 | |
| Southern Pine | #2 | 8-2 | 12-3 | 15-7 | 18-6 | 21-9 | 7-1 | 10-8 | 13-6 | 16-0 | 18-10 | |
| Southern Pine | #3 | 6-4 | 9-4 | 11-9 | 14-3 | 16-10 | 5-6 | 8-1 | 10-2 | 12-4 | 14-7 | |
| Spruce-Pine-Fir | SS | 9-1 | 14-3 | 18-9 | 23-11 | Note b | 9-1 | 13-7 | 17-2 | 21-0 | 24-4 | |
| Spruce-Pine-Fir | #1 | 8-10 | 13-1 | 16-7 | 20-3 | 23-6 | 7-9 | 11-4 | 14-4 | 17-7 | 20-4 | |
| Spruce-Pine-Fir | #2 | 8-10 | 13-1 | 16-7 | 20-3 | 23-6 | 7-9 | 11-4 | 14-4 | 17-7 | 20-4 | |
| Spruce-Pine-Fir | #3 | 6-9 | 9-11 | 12-7 | 15-4 | 17-9 | 5-10 | 8-7 | 10-10 | 13-3 | 15-5 | |
(continued)
TABLE 2308.7.2(1)‒continued RAFTER SPANS FOR COMMON LUMBER SPECIES (Roof Live Load = 20 psf, Ceiling Not Attached to Rafters, L/Δ = 180)
| RAFTER SPACING (inches) | SPECIES AND GRADE | DEAD LOAD = 10 psf | DEAD LOAD = 20 psf | |||||||||
| 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | |||
| Maximum rafter spansa | ||||||||||||
| (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | |||
| 24 | Douglas Fir-Larch | SS | 9-1 | 14-4 | 18-10 | 23-4 | Note b | 8-11 | 13-1 | 16-7 | 20-3 | 23-5 |
| Douglas Fir-Larch | #1 | 8-7 | 12-6 | 15-10 | 19-5 | 22-6 | 7-5 | 10-10 | 13-9 | 16-9 | 19-6 | |
| Douglas Fir-Larch | #2 | 8-0 | 11-9 | 14-10 | 18-2 | 21-0 | 6-11 | 10-2 | 12-10 | 15-8 | 18-3 | |
| Douglas Fir-Larch | #3 | 6-1 | 8-10 | 11-3 | 13-8 | 15-11 | 5-3 | 7-8 | 9-9 | 11-10 | 13-9 | |
| Hem-Fir | SS | 8-7 | 13-6 | 17-10 | 22-9 | Note b | 8-7 | 12-10 | 16-3 | 19-10 | 23-0 | |
| Hem-Fir | #1 | 8-4 | 12-3 | 15-6 | 18-11 | 21-11 | 7-3 | 10-7 | 13-5 | 16-4 | 19-0 | |
| Hem-Fir | #2 | 7-11 | 11-7 | 14-8 | 17-10 | 20-9 | 6-10 | 10-0 | 12-8 | 15-6 | 17-11 | |
| Hem-Fir | #3 | 6-1 | 8-10 | 11-3 | 13-8 | 15-11 | 5-3 | 7-8 | 9-9 | 11-10 | 13-9 | |
| Southern Pine | SS | 8-11 | 14-1 | 18-6 | 23-8 | Note b | 8-11 | 13-10 | 17-6 | 20-10 | 24-8 | |
| Southern Pine | #1 | 8-7 | 12-9 | 16-2 | 18-11 | 22-6 | 7-5 | 11-1 | 14-0 | 16-5 | 19-6 | |
| Southern Pine | #2 | 7-4 | 11-0 | 13-11 | 16-6 | 19-6 | 6-4 | 9-6 | 12-1 | 14-4 | 16-10 | |
| Southern Pine | #3 | 5-8 | 8-4 | 10-6 | 12-9 | 15-1 | 4-11 | 7-3 | 9-1 | 11-0 | 13-1 | |
| Spruce-Pine-Fir | SS | 8-5 | 13-3 | 17-5 | 21-8 | 25-2 | 8-4 | 12-2 | 15-4 | 18-9 | 21-9 | |
| Spruce-Pine-Fir | #1 | 8-0 | 11-9 | 14-10 | 18-2 | 21-0 | 6-11 | 10-2 | 12-10 | 15-8 | 18-3 | |
| Spruce-Pine-Fir | #2 | 8-0 | 11-9 | 14-10 | 18-2 | 21-0 | 6-11 | 10-2 | 12-10 | 15-8 | 18-3 | |
| Spruce-Pine-Fir | #3 | 6-1 | 8-10 | 11-3 | 13-8 | 15-11 | 5-3 | 7-8 | 9-9 | 11-10 | 13-9 | |
| 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 = 0.0479 kPa. |
| a. The tabulated rafter spans assume that ceiling joists are located at the bottom of the attic space or that some other method of resisting the outward push of the rafters on the bearing walls, such as rafter ties, is provided at that location. When ceiling joists or rafter ties are located higher in the attic space, the rafter spans shall be multiplied by the factors given below: |
| HC/HR | Rafter Span Adjustment Factor |
| 1/3 | 0.67 |
| 1/4 | 0.76 |
| 1/5 | 0.83 |
| 1/6 | 0.90 |
| 1/7.5 or less | 1.00 |
where:
| HC | = | Height of ceiling joists or rafter ties measured vertically above the top of the rafter support walls. |
| HR | = | Height of roof ridge measured vertically above the top of the rafter support walls. |
b. Span exceeds 26 feet in length.
TABLE 2308.7.2(2) RAFTER SPANS FOR COMMON LUMBER SPECIES (Roof Live Load = 20 psf, Ceiling Attached to Rafters, L/Δ = 240)
| RAFTER SPACING (inches) | SPECIES AND GRADE | DEAD LOAD = 10 psf | DEAD LOAD = 20 psf | |||||||||
| 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | |||
| Maximum rafter spansa | ||||||||||||
| (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | |||
| 12 | Douglas Fir-Larch | SS | 10-5 | 16-4 | 21-7 | Note b | Note b | 10-5 | 16-4 | 21-7 | Note b | Note b |
| Douglas Fir-Larch | #1 | 10-0 | 15-9 | 20-10 | Note b | Note b | 10-0 | 15-4 | 19-5 | 23-9 | Note b | |
| Douglas Fir-Larch | #2 | 9-10 | 15-6 | 20-5 | 25-8 | Note b | 9-10 | 14-4 | 18-2 | 22-3 | 25-9 | |
| Douglas Fir-Larch | #3 | 8-7 | 12-6 | 15-10 | 19-5 | 22-6 | 7-5 | 10-10 | 13-9 | 16-9 | 19-6 | |
| Hem-Fir | SS | 9-10 | 15-6 | 20-5 | Note b | Note b | 9-10 | 15-6 | 20-5 | Note b | Note b | |
| Hem-Fir | #1 | 9-8 | 15-2 | 19-11 | 25-5 | Note b | 9-8 | 14-11 | 18-11 | 23-2 | Note b | |
| Hem-Fir | #2 | 9-2 | 14-5 | 19-0 | 24-3 | Note b | 9-2 | 14-2 | 17-11 | 21-11 | 25-5 | |
| Hem-Fir | #3 | 8-7 | 12-6 | 15-10 | 19-5 | 22-6 | 7-5 | 10-10 | 13-9 | 16-9 | 19-6 | |
| Southern Pine | SS | 10-3 | 16-1 | 21-2 | Note b | Note b | 10-3 | 16-1 | 21-2 | Note b | Note b | |
| Southern Pine | #1 | 9-10 | 15-6 | 20-5 | 26-0 | 26-0 | 9-10 | 15-6 | 19-10 | 23-2 | 26-0 | |
| Southern Pine | #2 | 9-5 | 14-9 | 19-6 | 23-5 | 26-0 | 9-0 | 13-6 | 17-1 | 20-3 | 23-10 | |
| Southern Pine | #3 | 8-0 | 11-9 | 14-10 | 18-0 | 21-4 | 6-11 | 10-2 | 12-10 | 15-7 | 18-6 | |
| Spruce-Pine-Fir | SS | 9-8 | 15-2 | 19-11 | 25-5 | Note b | 9-8 | 15-2 | 19-11 | 25-5 | Note b | |
| Spruce-Pine-Fir | #1 | 9-5 | 14-9 | 19-6 | 24-10 | Note b | 9-5 | 14-4 | 18-2 | 22-3 | 25-9 | |
| Spruce-Pine-Fir | #2 | 9-5 | 14-9 | 19-6 | 24-10 | Note b | 9-5 | 14-4 | 18-2 | 22-3 | 25-9 | |
| Spruce-Pine-Fir | #3 | 8-7 | 12-6 | 15-10 | 19-5 | 22-6 | 7-5 | 10-10 | 13-9 | 16-9 | 19-6 | |
| 16 | Douglas Fir-Larch | SS | 9-6 | 14-11 | 19-7 | 25-0 | Note b | 9-6 | 14-11 | 19-7 | 24-9 | Note b |
| Douglas Fir-Larch | #1 | 9-1 | 14-4 | 18-11 | 23-9 | Note b | 9-1 | 13-3 | 16-10 | 20-7 | 23-10 | |
| Douglas Fir-Larch | #2 | 8-11 | 14-1 | 18-2 | 22-3 | 25-9 | 8-6 | 12-5 | 15-9 | 19-3 | 22-4 | |
| Douglas Fir-Larch | #3 | 7-5 | 10-10 | 13-9 | 16-9 | 19-6 | 6-5 | 9-5 | 11-11 | 14-6 | 16-10 | |
| Hem-Fir | SS | 8-11 | 14-1 | 18-6 | 23-8 | Note b | 8-11 | 14-1 | 18-6 | 23-8 | Note b | |
| Hem-Fir | #1 | 8-9 | 13-9 | 18-1 | 23-1 | Note b | 8-9 | 12-11 | 16-5 | 20-0 | 23-3 | |
| Hem-Fir | #2 | 8-4 | 13-1 | 17-3 | 21-11 | 25-5 | 8-4 | 12-3 | 15-6 | 18-11 | 22-0 | |
| Hem-Fir | #3 | 7-5 | 10-10 | 13-9 | 16-9 | 19-6 | 6-5 | 9-5 | 11-11 | 14-6 | 16-10 | |
| Southern Pine | SS | 9-4 | 14-7 | 19-3 | 24-7 | Note b | 9-4 | 14-7 | 19-3 | 24-7 | Note b | |
| Southern Pine | #1 | 8-11 | 14-1 | 18-6 | 23-2 | 26-0 | 8-11 | 13-7 | 17-2 | 20-1 | 23-10 | |
| Southern Pine | #2 | 8-7 | 13-5 | 17-1 | 20-3 | 23-10 | 7-9 | 11-8 | 14-9 | 17-6 | 20-8 | |
| Southern Pine | #3 | 6-11 | 10-2 | 12-10 | 15-7 | 18-6 | 6-0 | 8-10 | 11-2 | 13-6 | 16-0 | |
| Spruce-Pine-Fir | SS | 8-9 | 13-9 | 18-1 | 23-1 | Note b | 8-9 | 13-9 | 18-1 | 23-0 | Note b | |
| Spruce-Pine-Fir | #1 | 8-7 | 13-5 | 17-9 | 22-3 | 25-9 | 8-6 | 12-5 | 15-9 | 19-3 | 22-4 | |
| Spruce-Pine-Fir | #2 | 8-7 | 13-5 | 17-9 | 22-3 | 25-9 | 8-6 | 12-5 | 15-9 | 19-3 | 22-4 | |
| Spruce-Pine-Fir | #3 | 7-5 | 10-10 | 13-9 | 16-9 | 19-6 | 6-5 | 9-5 | 11-11 | 14-6 | 16-10 | |
| 19.2 | Douglas Fir-Larch | SS | 8-11 | 14-0 | 18-5 | 23-7 | Note b | 8-11 | 14-0 | 18-5 | 22-7 | Note b |
| Douglas Fir-Larch | #1 | 8-7 | 13-6 | 17-9 | 21-8 | 25-2 | 8-4 | 12-2 | 15-4 | 18-9 | 21-9 | |
| Douglas Fir-Larch | #2 | 8-5 | 13-1 | 16-7 | 20-3 | 23-6 | 7-9 | 11-4 | 14-4 | 17-7 | 20-4 | |
| Douglas Fir-Larch | #3 | 6-9 | 9-11 | 12-7 | 15-4 | 17-9 | 5-10 | 8-7 | 10-10 | 13-3 | 15-5 | |
| Hem-Fir | SS | 8-5 | 13-3 | 17-5 | 22-3 | Note b | 8-5 | 13-3 | 17-5 | 22-3 | 25-9 | |
| Hem-Fir | #1 | 8-3 | 12-11 | 17-1 | 21-1 | 24-6 | 8-1 | 11-10 | 15-0 | 18-4 | 21-3 | |
| Hem-Fir | #2 | 7-10 | 12-4 | 16-3 | 20-0 | 23-2 | 7-8 | 11-2 | 14-2 | 17-4 | 20-1 | |
| Hem-Fir | #3 | 6-9 | 9-11 | 12-7 | 15-4 | 17-9 | 5-10 | 8-7 | 10-10 | 13-3 | 15-5 | |
(continued)
TABLE 2308.7.2(2)‒continued RAFTER SPANS FOR COMMON LUMBER SPECIES (Roof Live Load = 20 psf, Ceiling Attached to Rafters, L/Δ = 240)
| RAFTER SPACING (inches) | SPECIES AND GRADE | DEAD LOAD = 10 psf | DEAD LOAD = 20 psf | |||||||||
| 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | |||
| Maximum rafter spansa | ||||||||||||
| (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | |||
| 19.2 | Southern Pine | SS | 8-9 | 13-9 | 18-2 | 23-1 | Note b | 8-9 | 13-9 | 18-2 | 23-1 | Note b |
| Southern Pine | #1 | 8-5 | 13-3 | 17-5 | 21-2 | 25-2 | 8-4 | 12-4 | 15-8 | 18-4 | 21-9 | |
| Southern Pine | #2 | 8-1 | 12-3 | 15-7 | 18-6 | 21-9 | 7-1 | 10-8 | 13-6 | 16-0 | 18-10 | |
| Southern Pine | #3 | 6-4 | 9-4 | 11-9 | 14-3 | 16-10 | 5-6 | 8-1 | 10-2 | 12-4 | 14-7 | |
| Spruce-Pine-Fir | SS | 8-3 | 12-11 | 17-1 | 21-9 | Note b | 8-3 | 12-11 | 17-1 | 21-0 | 24-4 | |
| Spruce-Pine-Fir | #1 | 8-1 | 12-8 | 16-7 | 20-3 | 23-6 | 7-9 | 11-4 | 14-4 | 17-7 | 20-4 | |
| Spruce-Pine-Fir | #2 | 8-1 | 12-8 | 16-7 | 20-3 | 23-6 | 7-9 | 11-4 | 14-4 | 17-7 | 20-4 | |
| Spruce-Pine-Fir | #3 | 6-9 | 9-11 | 12-7 | 15-4 | 17-9 | 5-10 | 8-7 | 10-10 | 13-3 | 15-5 | |
| 24 | Douglas Fir-Larch | SS | 8-3 | 13-0 | 17-2 | 21-10 | Note b | 8-3 | 13-0 | 16-7 | 20-3 | 23-5 |
| Douglas Fir-Larch | #1 | 8-0 | 12-6 | 15-10 | 19-5 | 22-6 | 7-5 | 10-10 | 13-9 | 16-9 | 19-6 | |
| Douglas Fir-Larch | #2 | 7-10 | 11-9 | 14-10 | 18-2 | 21-0 | 6-11 | 10-2 | 12-10 | 15-8 | 18-3 | |
| Douglas Fir-Larch | #3 | 6-1 | 8-10 | 11-3 | 13-8 | 15-11 | 5-3 | 7-8 | 9-9 | 11-10 | 13-9 | |
| Hem-Fir | SS | 7-10 | 12-3 | 16-2 | 20-8 | 25-1 | 7-10 | 12-3 | 16-2 | 19-10 | 23-0 | |
| Hem-Fir | #1 | 7-8 | 12-0 | 15-6 | 18-11 | 21-11 | 7-3 | 10-7 | 13-5 | 16-4 | 19-0 | |
| Hem-Fir | #2 | 7-3 | 11-5 | 14-8 | 17-10 | 20-9 | 6-10 | 10-0 | 12-8 | 15-6 | 17-11 | |
| Hem-Fir | #3 | 6-1 | 8-10 | 11-3 | 13-8 | 15-11 | 5-3 | 7-8 | 9-9 | 11-10 | 13-9 | |
| Southern Pine | SS | 8-1 | 12-9 | 16-10 | 21-6 | Note b | 8-1 | 12-9 | 16-10 | 20-10 | 24-8 | |
| Southern Pine | #1 | 7-10 | 12-3 | 16-2 | 18-11 | 22-6 | 7-5 | 11-1 | 14-0 | 16-5 | 19-6 | |
| Southern Pine | #2 | 7-4 | 11-0 | 13-11 | 16-6 | 19-6 | 6-4 | 9-6 | 12-1 | 14-4 | 16-10 | |
| Southern Pine | #3 | 5-8 | 8-4 | 10-6 | 12-9 | 15-1 | 4-11 | 7-3 | 9-1 | 11-0 | 13-1 | |
| Spruce-Pine-Fir | SS | 7-8 | 12-0 | 15-10 | 20-2 | 24-7 | 7-8 | 12-0 | 15-4 | 18-9 | 21-9 | |
| Spruce-Pine-Fir | #1 | 7-6 | 11-9 | 14-10 | 18-2 | 21-0 | 6-11 | 10-2 | 12-10 | 15-8 | 18-3 | |
| Spruce-Pine-Fir | #2 | 7-6 | 11-9 | 14-10 | 18-2 | 21-0 | 6-11 | 10-2 | 12-10 | 15-8 | 18-3 | |
| Spruce-Pine-Fir | #3 | 6-1 | 8-10 | 11-3 | 13-8 | 15-11 | 5-3 | 7-8 | 9-9 | 11-10 | 13-9 | |
| 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 = 0.0479 kPa. |
| a. The tabulated rafter spans assume that ceiling joists are located at the bottom of the attic space or that some other method of resisting the outward push of the rafters on the bearing walls, such as rafter ties, is provided at that location. When ceiling joists or rafter ties are located higher in the attic space, the rafter spans shall be multiplied by the factors given below: |
| HC/HR | Rafter Span Adjustment Factor |
| 1/3 | 0.67 |
| 1/4 | 0.76 |
| 1/5 | 0.83 |
| 1/6 | 0.90 |
| 1/7.5 or less | 1.00 |
where:
| HC | = | Height of ceiling joists or rafter ties measured vertically above the top of the rafter support walls. |
| HR | = | Height of roof ridge measured vertically above the top of the rafter support walls. |
| b. Span exceeds 26 feet in length. |
TABLE 2308.7.2(3) RAFTER SPANS FOR COMMON LUMBER SPECIES (Ground Snow Load = 30 psf, Ceiling Not Attached to Rafters, L/Δ = 180)
| RAFTER SPACING (inches) | SPECIES AND GRADE | DEAD LOAD = 10 psf | DEAD LOAD = 20 psf | |||||||||
| 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | |||
| Maximum rafter spansa | ||||||||||||
| (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | |||
| 12 | Douglas Fir-Larch | SS | 10-0 | 15-9 | 20-9 | Note b | Note b | 10-0 | 15-9 | 20-1 | 24-6 | Note b |
| Douglas Fir-Larch | #1 | 9-8 | 14-9 | 18-8 | 22-9 | Note b | 9-0 | 13-2 | 16-8 | 20-4 | 23-7 | |
| Douglas Fir-Larch | #2 | 9-5 | 13-9 | 17-5 | 21-4 | 24-8 | 8-5 | 12-4 | 15-7 | 19-1 | 22-1 | |
| Douglas Fir-Larch | #3 | 7-1 | 10-5 | 13-2 | 16-1 | 18-8 | 6-4 | 9-4 | 11-9 | 14-5 | 16-8 | |
| Hem-Fir | SS | 9-6 | 14-10 | 19-7 | 25-0 | Note b | 9-6 | 14-10 | 19-7 | 24-1 | Note b | |
| Hem-Fir | #1 | 9-3 | 14-4 | 18-2 | 22-2 | 25-9 | 8-9 | 12-10 | 16-3 | 19-10 | 23-0 | |
| Hem-Fir | #2 | 8-10 | 13-7 | 17-2 | 21-0 | 24-4 | 8-4 | 12-2 | 15-4 | 18-9 | 21-9 | |
| Hem-Fir | #3 | 7-1 | 10-5 | 13-2 | 16-1 | 18-8 | 6-4 | 9-4 | 11-9 | 14-5 | 16-8 | |
| Southern Pine | SS | 9-10 | 15-6 | 20-5 | Note b | Note b | 9-10 | 15-6 | 20-5 | 25-4 | Note b | |
| Southern Pine | #1 | 9-6 | 14-10 | 19-0 | 22-3 | 26-0 | 9-0 | 13-5 | 17-0 | 19-11 | 23-7 | |
| Southern Pine | #2 | 8-7 | 12-11 | 16-4 | 19-5 | 22-10 | 7-8 | 11-7 | 14-8 | 17-4 | 20-5 | |
| Southern Pine | #3 | 6-7 | 9-9 | 12-4 | 15-0 | 17-9 | 5-11 | 8-9 | 11-0 | 13-5 | 15-10 | |
| Spruce-Pine-Fir | SS | 9-3 | 14-7 | 19-2 | 24-6 | Note b | 9-3 | 14-7 | 18-8 | 22-9 | Note b | |
| Spruce-Pine-Fir | #1 | 9-1 | 13-9 | 17-5 | 21-4 | 24-8 | 8-5 | 12-4 | 15-7 | 19-1 | 22-1 | |
| Spruce-Pine-Fir | #2 | 9-1 | 13-9 | 17-5 | 21-4 | 24-8 | 8-5 | 12-4 | 15-7 | 19-1 | 22-1 | |
| Spruce-Pine-Fir | #3 | 7-1 | 10-5 | 13-2 | 16-1 | 18-8 | 6-4 | 9-4 | 11-9 | 14-5 | 16-8 | |
| 16 | Douglas Fir-Larch | SS | 9-1 | 14-4 | 18-10 | 23-9 | Note b | 9-1 | 13-9 | 17-5 | 21-3 | 24-8 |
| Douglas Fir-Larch | #1 | 8-9 | 12-9 | 16-2 | 19-9 | 22-10 | 7-10 | 11-5 | 14-5 | 17-8 | 20-5 | |
| Douglas Fir-Larch | #2 | 8-2 | 11-11 | 15-1 | 18-5 | 21-5 | 7-3 | 10-8 | 13-6 | 16-6 | 19-2 | |
| Douglas Fir-Larch | #3 | 6-2 | 9-0 | 11-5 | 13-11 | 16-2 | 5-6 | 8-1 | 10-3 | 12-6 | 14-6 | |
| Hem-Fir | SS | 8-7 | 13-6 | 17-10 | 22-9 | Note b | 8-7 | 13-6 | 17-1 | 20-10 | 24-2 | |
| Hem-Fir | #1 | 8-5 | 12-5 | 15-9 | 19-3 | 22-3 | 7-7 | 11-1 | 14-1 | 17-2 | 19-11 | |
| Hem-Fir | #2 | 8-0 | 11-9 | 14-11 | 18-2 | 21-1 | 7-2 | 10-6 | 13-4 | 16-3 | 18-10 | |
| Hem-Fir | #3 | 6-2 | 9-0 | 11-5 | 13-11 | 16-2 | 5-6 | 8-1 | 10-3 | 12-6 | 14-6 | |
| Southern Pine | SS | 8-11 | 14-1 | 18-6 | 23-8 | Note b | 8-11 | 14-1 | 18-5 | 21-11 | 25-11 | |
| Southern Pine | #1 | 8-7 | 13-0 | 16-6 | 19-3 | 22-10 | 7-10 | 11-7 | 14-9 | 17-3 | 20-5 | |
| Southern Pine | #2 | 7-6 | 11-2 | 14-2 | 16-10 | 19-10 | 6-8 | 10-0 | 12-8 | 15-1 | 17-9 | |
| Southern Pine | #3 | 5-9 | 8-6 | 10-8 | 13-0 | 15-4 | 5-2 | 7-7 | 9-7 | 11-7 | 13-9 | |
| Spruce-Pine-Fir | SS | 8-5 | 13-3 | 17-5 | 22-1 | 25-7 | 8-5 | 12-9 | 16-2 | 19-9 | 22-10 | |
| Spruce-Pine-Fir | #1 | 8-2 | 11-11 | 15-1 | 18-5 | 21-5 | 7-3 | 10-8 | 13-6 | 16-6 | 19-2 | |
| Spruce-Pine-Fir | #2 | 8-2 | 11-11 | 15-1 | 18-5 | 21-5 | 7-3 | 10-8 | 13-6 | 16-6 | 19-2 | |
| Spruce-Pine-Fir | #3 | 6-2 | 9-0 | 11-5 | 13-11 | 16-2 | 5-6 | 8-1 | 10-3 | 12-6 | 14-6 | |
| 19.2 | Douglas Fir-Larch | SS | 8-7 | 13-6 | 17-9 | 21-8 | 25-2 | 8-7 | 12-6 | 15-10 | 19-5 | 22-6 |
| Douglas Fir-Larch | #1 | 7-11 | 11-8 | 14-9 | 18-0 | 20-11 | 7-1 | 10-5 | 13-2 | 16-1 | 18-8 | |
| Douglas Fir-Larch | #2 | 7-5 | 10-11 | 13-9 | 16-10 | 19-6 | 6-8 | 9-9 | 12-4 | 15-1 | 17-6 | |
| Douglas Fir-Larch | #3 | 5-7 | 8-3 | 10-5 | 12-9 | 14-9 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | |
| Hem-Fir | SS | 8-1 | 12-9 | 16-9 | 21-4 | 24-8 | 8-1 | 12-4 | 15-7 | 19-1 | 22-1 | |
| Hem-Fir | #1 | 7-9 | 11-4 | 14-4 | 17-7 | 20-4 | 6-11 | 10-2 | 12-10 | 15-8 | 18-2 | |
| Hem-Fir | #2 | 7-4 | 10-9 | 13-7 | 16-7 | 19-3 | 6-7 | 9-7 | 12-2 | 14-10 | 17-3 | |
| Hem-Fir | #3 | 5-7 | 8-3 | 10-5 | 12-9 | 14-9 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | |
(continued)
TABLE 2308.7.2(3)‒continued RAFTER SPANS FOR COMMON LUMBER SPECIES (Ground Snow Load = 30 psf, Ceiling Not Attached to Rafters, L/Δ = 180)
| RAFTER SPACING (inches) | SPECIES AND GRADE | DEAD LOAD = 10 psf | DEAD LOAD = 20 psf | |||||||||
| 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | |||
| Maximum rafter spansa | ||||||||||||
| (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | |||
| 19.2 | Southern Pine | SS | 8-5 | 13-3 | 17-5 | 22-3 | Note b | 8-5 | 13-3 | 16-10 | 20-0 | 23-7 |
| Southern Pine | #1 | 8-0 | 11-10 | 15-1 | 17-7 | 20-11 | 7-1 | 10-7 | 13-5 | 15-9 | 18-8 | |
| Southern Pine | #2 | 6-10 | 10-2 | 12-11 | 15-4 | 18-1 | 6-1 | 9-2 | 11-7 | 13-9 | 16-2 | |
| Southern Pine | #3 | 5-3 | 7-9 | 9-9 | 11-10 | 14-0 | 4-8 | 6-11 | 8-9 | 10-7 | 12-6 | |
| Spruce-Pine-Fir | SS | 7-11 | 12-5 | 16-5 | 20-2 | 23-4 | 7-11 | 11-8 | 14-9 | 18-0 | 20-11 | |
| Spruce-Pine-Fir | #1 | 7-5 | 10-11 | 13-9 | 16-10 | 19-6 | 6-8 | 9-9 | 12-4 | 15-1 | 17-6 | |
| Spruce-Pine-Fir | #2 | 7-5 | 10-11 | 13-9 | 16-10 | 19-6 | 6-8 | 9-9 | 12-4 | 15-1 | 17-6 | |
| Spruce-Pine-Fir | #3 | 5-7 | 8-3 | 10-5 | 12-9 | 14-9 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | |
| 24 | Douglas Fir-Larch | SS | 7-11 | 12-6 | 15-10 | 19-5 | 22-6 | 7-8 | 11-3 | 14-2 | 17-4 | 20-1 |
| Douglas Fir-Larch | #1 | 7-1 | 10-5 | 13-2 | 16-1 | 18-8 | 6-4 | 9-4 | 11-9 | 14-5 | 16-8 | |
| Douglas Fir-Larch | #2 | 6-8 | 9-9 | 12-4 | 15-1 | 17-6 | 5-11 | 8-8 | 11-0 | 13-6 | 15-7 | |
| Douglas Fir-Larch | #3 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | 4-6 | 6-7 | 8-4 | 10-2 | 11-10 | |
| Hem-Fir | SS | 7-6 | 11-10 | 15-7 | 19-1 | 22-1 | 7-6 | 11-0 | 13-11 | 17-0 | 19-9 | |
| Hem-Fir | #1 | 6-11 | 10-2 | 12-10 | 15-8 | 18-2 | 6-2 | 9-1 | 11-6 | 14-0 | 16-3 | |
| Hem-Fir | #2 | 6-7 | 9-7 | 12-2 | 14-10 | 17-3 | 5-10 | 8-7 | 10-10 | 13-3 | 15-5 | |
| Hem-Fir | #3 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | 4-6 | 6-7 | 8-4 | 10-2 | 11-10 | |
| Southern Pine | SS | 7-10 | 12-3 | 16-2 | 20-0 | 23-7 | 7-10 | 11-10 | 15-0 | 17-11 | 21-2 | |
| Southern Pine | #1 | 7-1 | 10-7 | 13-5 | 15-9 | 18-8 | 6-4 | 9-6 | 12-0 | 14-1 | 16-8 | |
| Southern Pine | #2 | 6-1 | 9-2 | 11-7 | 13-9 | 16-2 | 5-5 | 8-2 | 10-4 | 12-3 | 14-6 | |
| Southern Pine | #3 | 4-8 | 6-11 | 8-9 | 10-7 | 12-6 | 4-2 | 6-2 | 7-10 | 9-6 | 11-2 | |
| Spruce-Pine-Fir | SS | 7-4 | 11-7 | 14-9 | 18-0 | 20-11 | 7-1 | 10-5 | 13-2 | 16-1 | 18-8 | |
| Spruce-Pine-Fir | #1 | 6-8 | 9-9 | 12-4 | 15-1 | 17-6 | 5-11 | 8-8 | 11-0 | 13-6 | 15-7 | |
| Spruce-Pine-Fir | #2 | 6-8 | 9-9 | 12-4 | 15-1 | 17-6 | 5-11 | 8-8 | 11-0 | 13-6 | 15-7 | |
| Spruce-Pine-Fir | #3 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | 4-6 | 6-7 | 8-4 | 10-2 | 11-10 | |
| 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 = 0.0479 kPa. |
| a. The tabulated rafter spans assume that ceiling joists are located at the bottom of the attic space or that some other method of resisting the outward push of the rafters on the bearing walls, such as rafter ties, is provided at that location. When ceiling joists or rafter ties are located higher in the attic space, the rafter spans shall be multiplied by the factors given below: |
| HC/HR | Rafter Span Adjustment Factor |
| 1/3 | 0.67 |
| 1/4 | 0.76 |
| 1/5 | 0.83 |
| 1/6 | 0.90 |
| 1/7.5 or less | 1.00 |
where:
| HC | = | Height of ceiling joists or rafter ties measured vertically above the top of the rafter support walls. |
| HR | = | Height of roof ridge measured vertically above the top of the rafter support walls. |
b. Span exceeds 26 feet in length.
TABLE 2308.7.2(4) RAFTER SPANS FOR COMMON LUMBER SPECIES (Ground Snow Load = 50 psf, Ceiling Not Attached to Rafters, L/Δ = 180)
| RAFTER SPACING (inches) | SPECIES AND GRADE | DEAD LOAD = 10 psf | DEAD LOAD = 20 psf | |||||||||
| 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | |||
| Maximum rafter spansa | ||||||||||||
| (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | |||
| 12 | Douglas Fir-Larch | SS | 8-5 | 13-3 | 17-6 | 22-4 | 26-0 | 8-5 | 13-3 | 17-0 | 20-9 | 24-0 |
| Douglas Fir-larch | #1 | 8-2 | 12-0 | 15-3 | 18-7 | 21-7 | 7-7 | 11-2 | 14-1 | 17-3 | 20-0 | |
| Douglas Fir-larch | #2 | 7-8 | 11-3 | 14-3 | 17-5 | 20-2 | 7-1 | 10-5 | 13-2 | 16-1 | 18-8 | |
| Douglas Fir-larch | #3 | 5-10 | 8-6 | 10-9 | 13-2 | 15-3 | 5-5 | 7-10 | 10-0 | 12-2 | 14-1 | |
| Hem-Fir | SS | 8-0 | 12-6 | 16-6 | 21-1 | 25-6 | 8-0 | 12-6 | 16-6 | 20-4 | 23-7 | |
| Hem-Fir | #1 | 7-10 | 11-9 | 14-10 | 18-1 | 21-0 | 7-5 | 10-10 | 13-9 | 16-9 | 19-5 | |
| Hem-Fir | #2 | 7-5 | 11-1 | 14-0 | 17-2 | 19-11 | 7-0 | 10-3 | 13-0 | 15-10 | 18-5 | |
| Hem-Fir | #3 | 5-10 | 8-6 | 10-9 | 13-2 | 15-3 | 5-5 | 7-10 | 10-0 | 12-2 | 14-1 | |
| Southern Pine | SS | 8-4 | 13-1 | 17-2 | 21-11 | Note b | 8-4 | 13-1 | 17-2 | 21-5 | 25-3 | |
| Southern Pine | #1 | 8-0 | 12-3 | 15-6 | 18-2 | 21-7 | 7-7 | 11-4 | 14-5 | 16-10 | 20-0 | |
| Southern Pine | #2 | 7-0 | 10-6 | 13-4 | 15-10 | 18-8 | 6-6 | 9-9 | 12-4 | 14-8 | 17-3 | |
| Southern Pine | #3 | 5-5 | 8-0 | 10-1 | 12-3 | 14-6 | 5-0 | 7-5 | 9-4 | 11-4 | 13-5 | |
| Spruce-Pine-Fir | SS | 7-10 | 12-3 | 16-2 | 20-8 | 24-1 | 7-10 | 12-3 | 15-9 | 19-3 | 22-4 | |
| Spruce-Pine-Fir | #1 | 7-8 | 11-3 | 14-3 | 17-5 | 20-2 | 7-1 | 10-5 | 13-2 | 16-1 | 18-8 | |
| Spruce-Pine-Fir | #2 | 7-8 | 11-3 | 14-3 | 17-5 | 20-2 | 7-1 | 10-5 | 13-2 | 16-1 | 18-8 | |
| Spruce-Pine-Fir | #3 | 5-10 | 8-6 | 10-9 | 13-2 | 15-3 | 5-5 | 7-10 | 10-0 | 12-2 | 14-1 | |
| 16 | Douglas Fir-Larch | SS | 7-8 | 12-1 | 15-10 | 19-5 | 22-6 | 7-8 | 11-7 | 14-8 | 17-11 | 20-10 |
| Douglas Fir-Larch | #1 | 7-1 | 10-5 | 13-2 | 16-1 | 18-8 | 6-7 | 9-8 | 12-2 | 14-11 | 17-3 | |
| Douglas Fir-Larch | #2 | 6-8 | 9-9 | 12-4 | 15-1 | 17-6 | 6-2 | 9-0 | 11-5 | 13-11 | 16-2 | |
| Douglas Fir-Larch | #3 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | 4-8 | 6-10 | 8-8 | 10-6 | 12-3 | |
| Hem-Fir | SS | 7-3 | 11-5 | 15-0 | 19-1 | 22-1 | 7-3 | 11-5 | 14-5 | 17-8 | 20-5 | |
| Hem-Fir | #1 | 6-11 | 10-2 | 12-10 | 15-8 | 18-2 | 6-5 | 9-5 | 11-11 | 14-6 | 16-10 | |
| Hem-Fir | #2 | 6-7 | 9-7 | 12-2 | 14-10 | 17-3 | 6-1 | 8-11 | 11-3 | 13-9 | 15-11 | |
| Hem-Fir | #3 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | 4-8 | 6-10 | 8-8 | 10-6 | 12-3 | |
| Southern Pine | SS | 7-6 | 11-10 | 15-7 | 19-11 | 23-7 | 7-6 | 11-10 | 15-7 | 18-6 | 21-10 | |
| Southern Pine | #1 | 7-1 | 10-7 | 13-5 | 15-9 | 18-8 | 6-7 | 9-10 | 12-5 | 14-7 | 17-3 | |
| Southern Pine | #2 | 6-1 | 9-2 | 11-7 | 13-9 | 16-2 | 5-8 | 8-5 | 10-9 | 12-9 | 15-0 | |
| Southern Pine | #3 | 4-8 | 6-11 | 8-9 | 10-7 | 12-6 | 4-4 | 6-5 | 8-1 | 9-10 | 11-7 | |
| Spruce-Pine-Fir | SS | 7-1 | 11-2 | 14-8 | 18-0 | 20-11 | 7-1 | 10-9 | 13-8 | 15-11 | 19-4 | |
| Spruce-Pine-Fir | #1 | 6-8 | 9-9 | 12-4 | 15-1 | 17-6 | 6-2 | 9-0 | 11-5 | 13-11 | 16-2 | |
| Spruce-Pine-Fir | #2 | 6-8 | 9-9 | 12-4 | 15-1 | 17-6 | 6-2 | 9-0 | 11-5 | 13-11 | 16-2 | |
| Spruce-Pine-Fir | #3 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | 4-8 | 6-10 | 8-8 | 10-6 | 12-3 | |
| 19.2 | Douglas Fir-Larch | SS | 7-3 | 11-4 | 14-6 | 17-8 | 20-6 | 7-3 | 10-7 | 13-5 | 16-5 | 19-0 |
| Douglas Fir-Larch | #1 | 6-6 | 9-6 | 12-0 | 14-8 | 17-1 | 6-0 | 8-10 | 11-2 | 13-7 | 15-9 | |
| Douglas Fir-Larch | #2 | 6-1 | 8-11 | 11-3 | 13-9 | 15-11 | 5-7 | 8-3 | 10-5 | 12-9 | 14-9 | |
| Douglas Fir-Larch | #3 | 4-7 | 6-9 | 8-6 | 10-5 | 12-1 | 4-3 | 6-3 | 7-11 | 9-7 | 11-2 | |
| Hem-Fir | SS | 6-10 | 10-9 | 14-2 | 17-5 | 20-2 | 6-10 | 10-5 | 13-2 | 16-1 | 18-8 | |
| Hem-Fir | #1 | 6-4 | 9-3 | 11-9 | 14-4 | 16-7 | 5-10 | 8-7 | 10-10 | 13-3 | 15-5 | |
| Hem-Fir | #2 | 6-0 | 8-9 | 11-1 | 13-7 | 15-9 | 5-7 | 8-1 | 10-3 | 12-7 | 14-7 | |
| Hem-Fir | #3 | 4-7 | 6-9 | 8-6 | 10-5 | 12-1 | 4-3 | 6-3 | 7-11 | 9-7 | 11-2 | |
(continued)
TABLE 2308.7.2(4) RAFTER SPANS FOR COMMON LUMBER SPECIES (Ground Snow Load = 50 psf, Ceiling Not Attached to Rafters, L/Δ = 180)
| RAFTER SPACING (inches) | SPECIES AND GRADE | DEAD LOAD = 10 psf | DEAD LOAD = 20 psf | |||||||||
| 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | |||
| Maximum rafter spansa | ||||||||||||
| (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | |||
| 19.2 | Southern Pine | SS | 7-1 | 11-2 | 14-8 | 18-3 | 21-7 | 7-1 | 11-2 | 14-2 | 16-11 | 20-0 |
| Southern Pine | #1 | 6-6 | 9-8 | 12-3 | 14-4 | 17-1 | 6-0 | 9-0 | 11-4 | 13-4 | 15-9 | |
| Southern Pine | #2 | 5-7 | 8-4 | 10-7 | 12-6 | 14-9 | 5-2 | 7-9 | 9-9 | 11-7 | 13-8 | |
| Southern Pine | #3 | 4-3 | 6-4 | 8-0 | 9-8 | 11-5 | 4-0 | 5-10 | 7-4 | 8-11 | 10-7 | |
| Spruce-Pine-Fir | SS | 6-8 | 10-6 | 13-5 | 16-5 | 19-1 | 6-8 | 9-10 | 12-5 | 15-3 | 17-8 | |
| Spruce-Pine-Fir | #1 | 6-1 | 8-11 | 11-3 | 13-9 | 15-11 | 5-7 | 8-3 | 10-5 | 12-9 | 14-9 | |
| Spruce-Pine-Fir | #2 | 6-1 | 8-11 | 11-3 | 13-9 | 15-11 | 5-7 | 8-3 | 10-5 | 12-9 | 14-9 | |
| Spruce-Pine-Fir | #3 | 4-7 | 6-9 | 8-6 | 10-5 | 12-1 | 4-3 | 6-3 | 7-11 | 9-7 | 11-2 | |
| 24 | Douglas Fir-Larch | SS | 6-8 | 10-3 | 13-0 | 15-10 | 18-4 | 6-6 | 9-6 | 12-0 | 14-8 | 17-0 |
| Douglas Fir-Larch | #1 | 5-10 | 8-6 | 10-9 | 13-2 | 15-3 | 5-5 | 7-10 | 10-0 | 12-2 | 14-1 | |
| Douglas Fir-Larch | #2 | 5-5 | 7-11 | 10-1 | 12-4 | 14-3 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | |
| Douglas Fir-Larch | #3 | 4-1 | 6-0 | 7-7 | 9-4 | 10-9 | 3-10 | 5-7 | 7-1 | 8-7 | 10-0 | |
| Hem-Fir | SS | 6-4 | 9-11 | 12-9 | 15-7 | 18-0 | 6-4 | 9-4 | 11-9 | 14-5 | 16-8 | |
| Hem-Fir | #1 | 5-8 | 8-3 | 10-6 | 12-10 | 14-10 | 5-3 | 7-8 | 9-9 | 11-10 | 13-9 | |
| Hem-Fir | #2 | 5-4 | 7-10 | 9-11 | 12-1 | 14-1 | 4-11 | 7-3 | 9-2 | 11-3 | 13-0 | |
| Hem-Fir | #3 | 4-1 | 6-0 | 7-7 | 9-4 | 10-9 | 3-10 | 5-7 | 7-1 | 8-7 | 10-0 | |
| Southern Pine | SS | 6-7 | 10-4 | 13-8 | 16-4 | 19-3 | 6-7 | 10-0 | 12-8 | 15-2 | 17-10 | |
| Southern Pine | #1 | 5-10 | 8-8 | 11-0 | 12-10 | 15-3 | 5-5 | 8-0 | 10-2 | 11-11 | 14-1 | |
| Southern Pine | #2 | 5-0 | 7-5 | 9-5 | 11-3 | 13-2 | 4-7 | 6-11 | 8-9 | 10-5 | 12-3 | |
| Southern Pine | #3 | 3-10 | 5-8 | 7-1 | 8-8 | 10-3 | 3-6 | 5-3 | 6-7 | 8-0 | 9-6 | |
| Spruce-Pine-Fir | SS | 6-2 | 9-6 | 12-0 | 14-8 | 17-1 | 6-0 | 8-10 | 11-2 | 13-7 | 15-9 | |
| Spruce-Pine-Fir | #1 | 5-5 | 7-11 | 10-1 | 12-4 | 14-3 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | |
| Spruce-Pine-Fir | #2 | 5-5 | 7-11 | 10-1 | 12-4 | 14-3 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | |
| Spruce-Pine-Fir | #3 | 4-1 | 6-0 | 7-7 | 9-4 | 10-9 | 3-10 | 5-7 | 7-1 | 8-7 | 10-0 | |
| 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 = 0.0479 kPa. |
| a. The tabulated rafter spans assume that ceiling joists are located at the bottom of the attic space or that some other method of resisting the outward push of the rafters on the bearing walls, such as rafter ties, is provided at that location. When ceiling joists or rafter ties are located higher in the attic space, the rafter spans shall be multiplied by the factors given below: |
| HC/HR | Rafter Span Adjustment Factor |
| 1/3 | 0.67 |
| 1/4 | 0.76 |
| 1/5 | 0.83 |
| 1/6 | 0.90 |
| 1/7.5 or less | 1.00 |
where:
| HC | = | Height of ceiling joists or rafter ties measured vertically above the top of the rafter support walls. |
| HR | = | Height of roof ridge measured vertically above the top of the rafter support walls. |
b. Span exceeds 26 feet in length.
TABLE 2308.7.2(5) RAFTER SPANS FOR COMMON LUMBER SPECIES (Ground Snow Load = 30 psf, Ceiling Attached to Rafters, L/Δ= 240)
| RAFTER SPACING (inches) | SPECIES AND GRADE | DEAD LOAD = 10 psf | DEAD LOAD = 20 psf | |||||||||
| 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | |||
| Maximum rafter spansa | ||||||||||||
| (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | |||
| 12 | Douglas Fir-Larch | SS | 9-1 | 14-4 | 18-10 | 24-1 | Note b | 9-1 | 14-4 | 18-10 | 24-1 | Note b |
| Douglas Fir-Larch | #1 | 8-9 | 13-9 | 18-2 | 22-9 | Note b | 8-9 | 13-2 | 16-8 | 20-4 | 23-7 | |
| Douglas Fir-Larch | #2 | 8-7 | 13-6 | 17-5 | 21-4 | 24-8 | 8-5 | 12-4 | 15-7 | 19-1 | 22-1 | |
| Douglas Fir-Larch | #3 | 7-1 | 10-5 | 13-2 | 16-1 | 18-8 | 6-4 | 9-4 | 11-9 | 14-5 | 16-8 | |
| Hem-Fir | SS | 8-7 | 13-6 | 17-10 | 22-9 | Note b | 8-7 | 13-6 | 17-10 | 22-9 | Note b | |
| Hem-Fir | #1 | 8-5 | 13-3 | 17-5 | 22-2 | 25-9 | 8-5 | 12-10 | 16-3 | 19-10 | 23-0 | |
| Hem-Fir | #2 | 8-0 | 12-7 | 16-7 | 21-0 | 24-4 | 8-0 | 12-2 | 15-4 | 18-9 | 21-9 | |
| Hem-Fir | #3 | 7-1 | 10-5 | 13-2 | 16-1 | 18-8 | 6-4 | 9-4 | 11-9 | 14-5 | 16-8 | |
| Southern Pine | SS | 8-11 | 14-1 | 18-6 | 23-8 | Note b | 8-11 | 14-1 | 18-6 | 23-8 | Note b | |
| Southern Pine | #1 | 8-7 | 13-6 | 17-10 | 22-3 | Note b | 8-7 | 13-5 | 17-0 | 19-11 | 23-7 | |
| Southern Pine | #2 | 8-3 | 12-11 | 16-4 | 19-5 | 22-10 | 7-8 | 11-7 | 14-8 | 17-4 | 20-5 | |
| Southern Pine | #3 | 6-7 | 9-9 | 12-4 | 15-0 | 17-9 | 5-11 | 8-9 | 11-0 | 13-5 | 15-10 | |
| Spruce-Pine-Fir | SS | 8-5 | 13-3 | 17-5 | 22-3 | Note b | 8-5 | 13-3 | 17-5 | 22-3 | Note b | |
| Spruce-Pine-Fir | #1 | 8-3 | 12-11 | 17-0 | 21-4 | 24-8 | 8-3 | 12-4 | 15-7 | 19-1 | 22-1 | |
| Spruce-Pine-Fir | #2 | 8-3 | 12-11 | 17-0 | 21-4 | 24-8 | 8-3 | 12-4 | 15-7 | 19-1 | 22-1 | |
| Spruce-Pine-Fir | #3 | 7-1 | 10-5 | 13-2 | 16-1 | 18-8 | 6-4 | 9-4 | 11-9 | 14-5 | 16-8 | |
| 16 | Douglas Fir-Larch | SS | 8-3 | 13-0 | 17-2 | 21-10 | Note b | 8-3 | 13-0 | 17-2 | 21-3 | 24-8 |
| Douglas Fir-Larch | #1 | 8-0 | 12-6 | 16-2 | 19-9 | 22-10 | 7-10 | 11-5 | 14-5 | 17-8 | 20-5 | |
| Douglas Fir-Larch | #2 | 7-10 | 11-11 | 15-1 | 18-5 | 21-5 | 7-3 | 10-8 | 13-6 | 16-6 | 19-2 | |
| Douglas Fir-Larch | #3 | 6-2 | 9-0 | 11-5 | 13-11 | 16-2 | 5-6 | 8-1 | 10-3 | 12-6 | 14-6 | |
| Hem-Fir | SS | 7-10 | 12-3 | 16-2 | 20-8 | 25-1 | 7-10 | 12-3 | 16-2 | 20-8 | 24-2 | |
| Hem-Fir | #1 | 7-8 | 12-0 | 15-9 | 19-3 | 22-3 | 7-7 | 11-1 | 14-1 | 17-2 | 19-11 | |
| Hem-Fir | #2 | 7-3 | 11-5 | 14-11 | 18-2 | 21-1 | 7-2 | 10-6 | 13-4 | 16-3 | 18-10 | |
| Hem-Fir | #3 | 6-2 | 9-0 | 11-5 | 13-11 | 16-2 | 5-6 | 8-1 | 10-3 | 12-6 | 14-6 | |
| Southern Pine | SS | 8-1 | 12-9 | 16-10 | 21-6 | Note b | 8-1 | 12-9 | 16-10 | 21-6 | 25-11 | |
| Southern Pine | #1 | 7-10 | 12-3 | 16-2 | 19-3 | 22-10 | 7-10 | 11-7 | 14-9 | 17-3 | 20-5 | |
| Southern Pine | #2 | 7-6 | 11-2 | 14-2 | 16-10 | 19-10 | 6-8 | 10-0 | 12-8 | 15-1 | 17-9 | |
| Southern Pine | #3 | 5-9 | 8-6 | 10-8 | 13-0 | 15-4 | 5-2 | 7-7 | 9-7 | 11-7 | 13-9 | |
| Spruce-Pine-Fir | SS | 7-8 | 12-0 | 15-10 | 20-2 | 24-7 | 7-8 | 12-0 | 15-10 | 19-9 | 22-10 | |
| Spruce-Pine-Fir | #1 | 7-6 | 11-9 | 15-1 | 18-5 | 21-5 | 7-3 | 10-8 | 13-6 | 16-6 | 19-2 | |
| Spruce-Pine-Fir | #2 | 7-6 | 11-9 | 15-1 | 18-5 | 21-5 | 7-3 | 10-8 | 13-6 | 16-6 | 19-2 | |
| Spruce-Pine-Fir | #3 | 6-2 | 9-0 | 11-5 | 13-11 | 16-2 | 5-6 | 8-1 | 10-3 | 12-6 | 14-6 | |
| 19.2 | Douglas Fir-Larch | SS | 7-9 | 12-3 | 16-1 | 20-7 | 25-0 | 7-9 | 12-3 | 15-10 | 19-5 | 22-6 |
| Douglas Fir-Larch | #1 | 7-6 | 11-8 | 14-9 | 18-0 | 20-11 | 7-1 | 10-5 | 13-2 | 16-1 | 18-8 | |
| Douglas Fir-Larch | #2 | 7-4 | 10-11 | 13-9 | 16-10 | 19-6 | 6-8 | 9-9 | 12-4 | 15-1 | 17-6 | |
| Douglas Fir-Larch | #3 | 5-7 | 8-3 | 10-5 | 12-9 | 14-9 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | |
| Hem-Fir | SS | 7-4 | 11-7 | 15-3 | 19-5 | 23-7 | 7-4 | 11-7 | 15-3 | 19-1 | 22-1 | |
| Hem-Fir | #1 | 7-2 | 11-4 | 14-4 | 17-7 | 20-4 | 6-11 | 10-2 | 12-10 | 15-8 | 18-2 | |
| Hem-Fir | #2 | 6-10 | 10-9 | 13-7 | 16-7 | 19-3 | 6-7 | 9-7 | 12-2 | 14-10 | 17-3 | |
| Hem-Fir | #3 | 5-7 | 8-3 | 10-5 | 12-9 | 14-9 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | |
(continued)
TABLE 2308.7.2(5)‒continued RAFTER SPANS FOR COMMON LUMBER SPECIES (Ground Snow Load = 30 psf, Ceiling Attached to Rafters, L/Δ = 240)
| RAFTER SPACING (inches) | SPECIES AND GRADE | DEAD LOAD = 10 psf | DEAD LOAD = 20 psf | |||||||||
| 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | |||
| Maximum rafter spansa | ||||||||||||
| (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | |||
| 19.2 | Southern Pine | SS | 7-8 | 12-0 | 15-10 | 20-2 | 24-7 | 7-8 | 12-0 | 15-10 | 20-0 | 23-7 |
| Southern Pine | #1 | 7-4 | 11-7 | 15-1 | 17-7 | 20-11 | 7-1 | 10-7 | 13-5 | 15-9 | 18-8 | |
| Southern Pine | #2 | 6-10 | 10-2 | 12-11 | 15-4 | 18-1 | 6-1 | 9-2 | 11-7 | 13-9 | 16-2 | |
| Southern Pine | #3 | 5-3 | 7-9 | 9-9 | 11-10 | 14-0 | 4-8 | 6-11 | 8-9 | 10-7 | 12-6 | |
| Spruce-Pine-Fir | SS | 7-2 | 11-4 | 14-11 | 19-0 | 23-1 | 7-2 | 11-4 | 14-9 | 18-0 | 20-11 | |
| Spruce-Pine-Fir | #1 | 7-0 | 10-11 | 13-9 | 16-10 | 19-6 | 6-8 | 9-9 | 12-4 | 15-1 | 17-6 | |
| Spruce-Pine-Fir | #2 | 7-0 | 10-11 | 13-9 | 16-10 | 19-6 | 6-8 | 9-9 | 12-4 | 15-1 | 17-6 | |
| Spruce-Pine-Fir | #3 | 5-7 | 8-3 | 10-5 | 12-9 | 14-9 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | |
| 24 | Douglas Fir-Larch | SS | 7-3 | 11-4 | 15-0 | 19-1 | 22-6 | 7-3 | 11-3 | 14-2 | 17-4 | 20-1 |
| Douglas Fir-Larch | #1 | 7-0 | 10-5 | 13-2 | 16-1 | 18-8 | 6-4 | 9-4 | 11-9 | 14-5 | 16-8 | |
| Douglas Fir-Larch | #2 | 6-8 | 9-9 | 12-4 | 15-1 | 17-6 | 5-11 | 8-8 | 11-0 | 13-6 | 15-7 | |
| Douglas Fir-Larch | #3 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | 4-6 | 6-7 | 8-4 | 10-2 | 11-10 | |
| Hem-Fir | SS | 6-10 | 10-9 | 14-2 | 18-0 | 21-11 | 6-10 | 10-9 | 13-11 | 17-0 | 19-9 | |
| Hem-Fir | #1 | 6-8 | 10-2 | 12-10 | 15-8 | 18-2 | 6-2 | 9-1 | 11-6 | 14-0 | 16-3 | |
| Hem-Fir | #2 | 6-4 | 9-7 | 12-2 | 14-10 | 17-3 | 5-10 | 8-7 | 10-10 | 13-3 | 15-5 | |
| Hem-Fir | #3 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | 4-6 | 6-7 | 8-4 | 10-2 | 11-10 | |
| Southern Pine | SS | 7-1 | 11-2 | 14-8 | 18-9 | 22-10 | 7-1 | 11-2 | 14-8 | 17-11 | 21-2 | |
| Southern Pine | #1 | 6-10 | 10-7 | 13-5 | 15-9 | 18-8 | 6-4 | 9-6 | 12-0 | 14-1 | 16-8 | |
| Southern Pine | #2 | 6-1 | 9-2 | 11-7 | 13-9 | 16-2 | 5-5 | 8-2 | 10-4 | 12-3 | 14-6 | |
| Southern Pine | #3 | 4-8 | 6-11 | 8-9 | 10-7 | 12-6 | 4-2 | 6-2 | 7-10 | 9-6 | 11-2 | |
| Spruce-Pine-Fir | SS | 6-8 | 10-6 | 13-10 | 17-8 | 20-11 | 6-8 | 10-5 | 13-2 | 16-1 | 18-8 | |
| Spruce-Pine-Fir | #1 | 6-6 | 9-9 | 12-4 | 15-1 | 17-6 | 5-11 | 8-8 | 11-0 | 13-6 | 15-7 | |
| Spruce-Pine-Fir | #2 | 6-6 | 9-9 | 12-4 | 15-1 | 17-6 | 5-11 | 8-8 | 11-0 | 13-6 | 15-7 | |
| Spruce-Pine-Fir | #3 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | 4-6 | 6-7 | 8-4 | 10-2 | 11-10 | |
| 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 = 0.0479 kPa. |
| a. The tabulated rafter spans assume that ceiling joists are located at the bottom of the attic space or that some other method of resisting the outward push of the rafters on the bearing walls, such as rafter ties, is provided at that location. When ceiling joists or rafter ties are located higher in the attic space, the rafter spans shall be multiplied by the factors given below: |
| HC/HR | Rafter Span Adjustment Factor |
| 1/3 | 0.67 |
| 1/4 | 0.76 |
| 1/5 | 0.83 |
| 1/6 | 0.90 |
| 1/7.5 or less | 1.00 |
where:
| HC | = | Height of ceiling joists or rafter ties measured vertically above the top of the rafter support walls. |
| HR | = | Height of roof ridge measured vertically above the top of the rafter support walls. |
b. Span exceeds 26 feet in length.
TABLE 2308.7.2(6) RAFTER SPANS FOR COMMON LUMBER SPECIES (Ground Snow Load = 50 psf, Ceiling Attached to Rafters, L/Δ = 240)
| RAFTER SPACING (inches) | SPECIES AND GRADE | DEAD LOAD = 10 psf | DEAD LOAD = 20 psf | |||||||||
| 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | |||
| Maximum rafter spansa | ||||||||||||
| (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | |||
| 12 | Douglas Fir-Larch | SS | 7-8 | 12-1 | 15-11 | 20-3 | 24-8 | 7-8 | 12-1 | 15-11 | 20-3 | 24-0 |
| Douglas Fir-Larch | #1 | 7-5 | 11-7 | 15-3 | 18-7 | 21-7 | 7-5 | 11-2 | 14-1 | 17-3 | 20-0 | |
| Douglas Fir-Larch | #2 | 7-3 | 11-3 | 14-3 | 17-5 | 20-2 | 7-1 | 10-5 | 13-2 | 16-1 | 18-8 | |
| Douglas Fir-Larch | #3 | 5-10 | 8-6 | 10-9 | 13-2 | 15-3 | 5-5 | 7-10 | 10-0 | 12-2 | 14-1 | |
| Hem-Fir | SS | 7-3 | 11-5 | 15-0 | 19-2 | 23-4 | 7-3 | 11-5 | 15-0 | 19-2 | 23-4 | |
| Hem-Fir | #1 | 7-1 | 11-2 | 14-8 | 18-1 | 21-0 | 7-1 | 10-10 | 13-9 | 16-9 | 19-5 | |
| Hem-Fir | #2 | 6-9 | 10-8 | 14-0 | 17-2 | 19-11 | 6-9 | 10-3 | 13-0 | 15-10 | 18-5 | |
| Hem-Fir | #3 | 5-10 | 8-6 | 10-9 | 13-2 | 15-3 | 5-5 | 7-10 | 10-0 | 12-2 | 14-1 | |
| Southern Pine | SS | 7-6 | 11-10 | 15-7 | 19-11 | 24-3 | 7-6 | 11-10 | 15-7 | 19-11 | 24-3 | |
| Southern Pine | #1 | 7-3 | 11-5 | 15-0 | 18-2 | 21-7 | 7-3 | 11-4 | 14-5 | 16-10 | 20-0 | |
| Southern Pine | #2 | 6-11 | 10-6 | 13-4 | 15-10 | 18-8 | 6-6 | 9-9 | 12-4 | 14-8 | 17-3 | |
| Southern Pine | #3 | 5-5 | 8-0 | 10-1 | 12-3 | 14-6 | 5-0 | 7-5 | 9-4 | 11-4 | 13-5 | |
| Spruce-Pine-Fir | SS | 7-1 | 11-2 | 14-8 | 18-9 | 22-10 | 7-1 | 11-2 | 14-8 | 18-9 | 22-4 | |
| Spruce-Pine-Fir | #1 | 6-11 | 10-11 | 14-3 | 17-5 | 20-2 | 6-11 | 10-5 | 13-2 | 16-1 | 18-8 | |
| Spruce-Pine-Fir | #2 | 6-11 | 10-11 | 14-3 | 17-5 | 20-2 | 6-11 | 10-5 | 13-2 | 16-1 | 18-8 | |
| Spruce-Pine-Fir | #3 | 5-10 | 8-6 | 10-9 | 13-2 | 15-3 | 5-5 | 7-10 | 10-0 | 12-2 | 14-1 | |
| 16 | Douglas Fir-Larch | SS | 7-0 | 11-0 | 14-5 | 18-5 | 22-5 | 7-0 | 11-0 | 14-5 | 17-11 | 20-10 |
| Douglas Fir-Larch | #1 | 6-9 | 10-5 | 13-2 | 16-1 | 18-8 | 6-7 | 9-8 | 12-2 | 14-11 | 17-3 | |
| Douglas Fir-Larch | #2 | 6-7 | 9-9 | 12-4 | 15-1 | 17-6 | 6-2 | 9-0 | 11-5 | 13-11 | 16-2 | |
| Douglas Fir-Larch | #3 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | 4-8 | 6-10 | 8-8 | 10-6 | 12-3 | |
| Hem-Fir | SS | 6-7 | 10-4 | 13-8 | 17-5 | 21-2 | 6-7 | 10-4 | 13-8 | 17-5 | 20-5 | |
| Hem-Fir | #1 | 6-5 | 10-2 | 12-10 | 15-8 | 18-2 | 6-5 | 9-5 | 11-11 | 14-6 | 16-10 | |
| Hem-Fir | #2 | 6-2 | 9-7 | 12-2 | 14-10 | 17-3 | 6-1 | 8-11 | 11-3 | 13-9 | 15-11 | |
| Hem-Fir | #3 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | 4-8 | 6-10 | 8-8 | 10-6 | 12-3 | |
| Southern Pine | SS | 6-10 | 10-9 | 14-2 | 18-1 | 22-0 | 6-10 | 10-9 | 14-2 | 18-1 | 21-10 | |
| Southern Pine | #1 | 6-7 | 10-4 | 13-5 | 15-9 | 18-8 | 6-7 | 9-10 | 12-5 | 14-7 | 17-3 | |
| Southern Pine | #2 | 6-1 | 9-2 | 11-7 | 13-9 | 16-2 | 5-8 | 8-5 | 10-9 | 12-9 | 15-0 | |
| Southern Pine | #3 | 4-8 | 6-11 | 8-9 | 10-7 | 12-6 | 4-4 | 6-5 | 8-1 | 9-10 | 11-7 | |
| Spruce-Pine-Fir | SS | 6-5 | 10-2 | 13-4 | 17-0 | 20-9 | 6-5 | 10-2 | 13-4 | 16-8 | 19-4 | |
| Spruce-Pine-Fir | #1 | 6-4 | 9-9 | 12-4 | 15-1 | 17-6 | 6-2 | 9-0 | 11-5 | 13-11 | 16-2 | |
| Spruce-Pine-Fir | #2 | 6-4 | 9-9 | 12-4 | 15-1 | 17-6 | 6-2 | 9-0 | 11-5 | 13-11 | 16-2 | |
| Spruce-Pine-Fir | #3 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | 4-8 | 6-10 | 8-8 | 10-6 | 12-3 | |
| 19.2 | Douglas Fir-Larch | SS | 6-7 | 10-4 | 13-7 | 17-4 | 20-6 | 6-7 | 10-4 | 13-5 | 16-5 | 19-0 |
| Douglas Fir-Larch | #1 | 6-4 | 9-6 | 12-0 | 14-8 | 17-1 | 6-0 | 8-10 | 11-2 | 13-7 | 15-9 | |
| Douglas Fir-Larch | #2 | 6-1 | 8-11 | 11-3 | 13-9 | 15-11 | 5-7 | 8-3 | 10-5 | 12-9 | 14-9 | |
| Douglas Fir-Larch | #3 | 4-7 | 6-9 | 8-6 | 10-5 | 12-1 | 4-3 | 6-3 | 7-11 | 9-7 | 11-2 | |
| Hem-Fir | SS | 6-2 | 9-9 | 12-10 | 16-5 | 19-11 | 6-2 | 9-9 | 12-10 | 16-1 | 18-8 | |
| Hem-Fir | #1 | 6-1 | 9-3 | 11-9 | 14-4 | 16-7 | 5-10 | 8-7 | 10-10 | 13-3 | 15-5 | |
| Hem-Fir | #2 | 5-9 | 8-9 | 11-1 | 13-7 | 15-9 | 5-7 | 8-1 | 10-3 | 12-7 | 14-7 | |
| Hem-Fir | #3 | 4-7 | 6-9 | 8-6 | 10-5 | 12-1 | 4-3 | 6-3 | 7-11 | 9-7 | 11-2 | |
(continued)
TABLE 2308.7.2(6)‒continued RAFTER SPANS FOR COMMON LUMBER SPECIES (Ground Snow Load = 50 psf, Ceiling Attached to Rafters, L/Δ = 240)
| RAFTER SPACING (inches) | SPECIES AND GRADE | DEAD LOAD = 10 psf | DEAD LOAD = 20 psf | |||||||||
| 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | 2 × 4 | 2 × 6 | 2 × 8 | 2 × 10 | 2 × 12 | |||
| Maximum rafter spansa | ||||||||||||
| (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | (ft. - in.) | |||
| 19.2 | Southern Pine | SS | 6-5 | 10-2 | 13-4 | 17-0 | 20-9 | 6-5 | 10-2 | 13-4 | 16-11 | 20-0 |
| Southern Pine | #1 | 6-2 | 9-8 | 12-3 | 14-4 | 17-1 | 6-0 | 9-0 | 11-4 | 13-4 | 15-9 | |
| Southern Pine | #2 | 5-7 | 8-4 | 10-7 | 12-6 | 14-9 | 5-2 | 7-9 | 9-9 | 11-7 | 13-8 | |
| Southern Pine | #3 | 4-3 | 6-4 | 8-0 | 9-8 | 11-5 | 4-0 | 5-10 | 7-4 | 8-11 | 10-7 | |
| Spruce-Pine-Fir | SS | 6-1 | 9-6 | 12-7 | 16-0 | 19-1 | 6-1 | 9-6 | 12-5 | 15-3 | 17-8 | |
| Spruce-Pine-Fir | #1 | 5-11 | 8-11 | 11-3 | 13-9 | 15-11 | 5-7 | 8-3 | 10-5 | 12-9 | 14-9 | |
| Spruce-Pine-Fir | #2 | 5-11 | 8-11 | 11-3 | 13-9 | 15-11 | 5-7 | 8-3 | 10-5 | 12-9 | 14-9 | |
| Spruce-Pine-Fir | #3 | 4-7 | 6-9 | 8-6 | 10-5 | 12-1 | 4-3 | 6-3 | 7-11 | 9-7 | 11-2 | |
| 24 | Douglas Fir-Larch | SS | 6-1 | 9-7 | 12-7 | 15-10 | 18-4 | 6-1 | 9-6 | 12-0 | 14-8 | 17-0 |
| Douglas Fir-Larch | #1 | 5-10 | 8-6 | 10-9 | 13-2 | 15-3 | 5-5 | 7-10 | 10-0 | 12-2 | 14-1 | |
| Douglas Fir-Larch | #2 | 5-5 | 7-11 | 10-1 | 12-4 | 14-3 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | |
| Douglas Fir-Larch | #3 | 4-1 | 6-0 | 7-7 | 9-4 | 10-9 | 3-10 | 5-7 | 7-1 | 8-7 | 10-0 | |
| Hem-Fir | SS | 5-9 | 9-1 | 11-11 | 15-2 | 18-0 | 5-9 | 9-1 | 11-9 | 14-5 | 15-11 | |
| Hem-Fir | #1 | 5-8 | 8-3 | 10-6 | 12-10 | 14-10 | 5-3 | 7-8 | 9-9 | 11-10 | 13-9 | |
| Hem-Fir | #2 | 5-4 | 7-10 | 9-11 | 12-1 | 14-1 | 4-11 | 7-3 | 9-2 | 11-3 | 13-0 | |
| Hem-Fir | #3 | 4-1 | 6-0 | 7-7 | 9-4 | 10-9 | 3-10 | 5-7 | 7-1 | 8-7 | 10-0 | |
| Southern Pine | SS | 6-0 | 9-5 | 12-5 | 15-10 | 19-3 | 6-0 | 9-5 | 12-5 | 15-2 | 17-10 | |
| Southern Pine | #1 | 5-9 | 8-8 | 11-0 | 12-10 | 15-3 | 5-5 | 8-0 | 10-2 | 11-11 | 14-1 | |
| Southern Pine | #2 | 5-0 | 7-5 | 9-5 | 11-3 | 13-2 | 4-7 | 6-11 | 8-9 | 10-5 | 12-3 | |
| Southern Pine | #3 | 3-10 | 5-8 | 7-1 | 8-8 | 10-3 | 3-6 | 5-3 | 6-7 | 8-0 | 9-6 | |
| Spruce-Pine-Fir | SS | 5-8 | 8-10 | 11-8 | 14-8 | 17-1 | 5-8 | 8-10 | 11-2 | 13-7 | 15-9 | |
| Spruce-Pine-Fir | #1 | 5-5 | 7-11 | 10-1 | 12-4 | 14-3 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | |
| Spruce-Pine-Fir | #2 | 5-5 | 7-11 | 10-1 | 12-4 | 14-3 | 5-0 | 7-4 | 9-4 | 11-5 | 13-2 | |
| Spruce-Pine-Fir | #3 | 4-1 | 6-0 | 7-7 | 9-4 | 10-9 | 3-10 | 5-7 | 7-1 | 8-7 | 10-0 | |
| 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 = 0.0479 kPa. |
| a. The tabulated rafter spans assume that ceiling joists are located at the bottom of the attic space or that some other method of resisting the outward push of the rafters on the bearing walls, such as rafter ties, is provided at that location. When ceiling joists or rafter ties are located higher in the attic space, the rafter spans shall be multiplied by the factors given below: |
| HC/HR | Rafter Span Adjustment Factor |
| 1/3 | 0.67 |
| 1/4 | 0.76 |
| 1/5 | 0.83 |
| 1/6 | 0.90 |
| 1/7.5 or less | 1.00 |
where:
| HC | = | Height of ceiling joists or rafter ties measured vertically above the top of the rafter support walls. |
| HR | = | Height of roof ridge measured vertically above the top of the rafter support walls. |
b. Span exceeds 26 feet in length.
Rafters shall be framed directly opposite each other at the ridge. There shall be a ridge board not less than 1-inch (25 mm) nominal thickness at ridges and not less in depth than the cut end of the rafter. At valleys and hips, there shall be a single valley or hip rafter not less than 2-inch (51 mm) nominal thickness and not less in depth than the cut end of the rafter.
Ceiling joists and rafters shall be nailed to each other and the assembly shall be nailed to the top wall plate in accordance with Tables 2304.10.1 and 2308.7.5. Ceiling joists shall be continuous or securely joined where they meet over interior partitions and be fastened to adjacent rafters in accordance with Tables 2304.10.1 and 2308.7.3.1 to provide a continuous rafter tie across the building where such joists are parallel to the rafters. Ceiling joists shall have a bearing surface of not less than 11/2 inches (38 mm) on the top plate at each end.
Where ceiling joists are not parallel to rafters, an equivalent rafter tie shall be installed in a manner to provide a continuous tie across the building, at a spacing of not more than 4 feet (1219 mm) on center. The connections shall be in accordance with Tables 2308.7.3.1 and 2304.10.1, or connections of equivalent capacities shall be provided. Where ceiling joists or rafter ties are not provided at the top of the rafter support walls, the ridge formed by these rafters shall also be supported by a girder conforming to Section 2308.8. Rafter ties shall be spaced not more than 4 feet (1219 mm) on center.
Rafter tie connections shall be based on the equivalent rafter spacing in Table 2308.7.3.1. Rafter-to-ceiling joist connections and rafter tie connections shall be of sufficient size and number to prevent splitting from nailing.
Roof framing member connection to braced wall lines shall be in accordance with Section 2308.6.7.2.
TABLE 2308.7.3.1 RAFTER TIE CONNECTIONSg
Where ceiling joists are not parallel to rafters, an equivalent rafter tie shall be installed in a manner to provide a continuous tie across the building, at a spacing of not more than 4 feet (1219 mm) on center. The connections shall be in accordance with Tables 2308.7.3.1 and 2304.10.1, or connections of equivalent capacities shall be provided. Where ceiling joists or rafter ties are not provided at the top of the rafter support walls, the ridge formed by these rafters shall also be supported by a girder conforming to Section 2308.8. Rafter ties shall be spaced not more than 4 feet (1219 mm) on center.
Rafter tie connections shall be based on the equivalent rafter spacing in Table 2308.7.3.1. Rafter-to-ceiling joist connections and rafter tie connections shall be of sufficient size and number to prevent splitting from nailing.
Roof framing member connection to braced wall lines shall be in accordance with Section 2308.6.7.2.
TABLE 2308.7.3.1 RAFTER TIE CONNECTIONSg
| RAFTER SLOPE | TIE SPACING (inches) | NO SNOW LOAD | GROUND SNOW LOAD (pound per square foot) | |||||||||||
| 30 pounds per square foot | 50 pounds per square foot | |||||||||||||
| Roof span (feet) | ||||||||||||||
| 12 | 20 | 28 | 36 | 12 | 20 | 28 | 36 | 12 | 20 | 28 | 36 | |||
| Required number of 16d common (31/2″ x 0.162″) nailsa, b per connectionc, d, e, f | ||||||||||||||
| 3:12 | 12 | 4 | 6 | 8 | 10 | 4 | 6 | 8 | 11 | 5 | 8 | 12 | 15 | |
| 16 | 5 | 7 | 10 | 13 | 5 | 8 | 11 | 14 | 6 | 11 | 15 | 20 | ||
| 24 | 7 | 11 | 15 | 19 | 7 | 11 | 16 | 21 | 9 | 16 | 23 | 30 | ||
| 32 | 10 | 14 | 19 | 25 | 10 | 16 | 22 | 28 | 12 | 27 | 30 | 40 | ||
| 48 | 14 | 21 | 29 | 37 | 14 | 32 | 36 | 42 | 18 | 32 | 46 | 60 | ||
| 4:12 | 12 | 3 | 4 | 5 | 6 | 3 | 5 | 6 | 8 | 4 | 6 | 9 | 11 | |
| 16 | 3 | 5 | 7 | 8 | 4 | 6 | 8 | 11 | 5 | 8 | 12 | 15 | ||
| 24 | 4 | 7 | 10 | 12 | 5 | 9 | 12 | 16 | 7 | 12 | 17 | 22 | ||
| 32 | 6 | 9 | 13 | 16 | 8 | 12 | 16 | 22 | 10 | 16 | 24 | 30 | ||
| 48 | 8 | 14 | 19 | 24 | 10 | 18 | 24 | 32 | 14 | 24 | 34 | 44 | ||
| 5:12 | 12 | 3 | 3 | 4 | 5 | 3 | 4 | 5 | 7 | 3 | 5 | 7 | 9 | |
| 16 | 3 | 4 | 5 | 7 | 3 | 5 | 7 | 9 | 4 | 7 | 9 | 12 | ||
| 24 | 4 | 6 | 8 | 10 | 4 | 7 | 10 | 13 | 6 | 10 | 14 | 18 | ||
| 32 | 5 | 8 | 10 | 13 | 6 | 10 | 14 | 18 | 8 | 14 | 18 | 24 | ||
| 48 | 7 | 11 | 15 | 20 | 8 | 14 | 20 | 26 | 12 | 20 | 28 | 36 | ||
| 7:12 | 12 | 3 | 3 | 3 | 4 | 3 | 3 | 4 | 5 | 3 | 4 | 5 | 7 | |
| 16 | 3 | 3 | 4 | 5 | 3 | 4 | 5 | 6 | 3 | 5 | 7 | 9 | ||
| 24 | 3 | 4 | 6 | 7 | 3 | 5 | 7 | 9 | 4 | 7 | 10 | 13 | ||
| 32 | 4 | 6 | 8 | 10 | 4 | 8 | 10 | 12 | 6 | 10 | 14 | 18 | ||
| 48 | 5 | 8 | 11 | 14 | 6 | 10 | 14 | 18 | 9 | 14 | 20 | 26 | ||
| 9:12 | 12 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 4 | 3 | 3 | 4 | 5 | |
| 16 | 3 | 3 | 3 | 4 | 3 | 3 | 4 | 5 | 3 | 4 | 5 | 7 | ||
| 24 | 3 | 3 | 5 | 6 | 3 | 4 | 6 | 7 | 3 | 6 | 8 | 10 | ||
| 32 | 3 | 4 | 6 | 8 | 4 | 6 | 8 | 10 | 5 | 8 | 10 | 14 | ||
| 48 | 4 | 6 | 9 | 11 | 5 | 8 | 12 | 14 | 7 | 12 | 16 | 20 | ||
| 12:12 | 12 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 4 | |
| 16 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 4 | 3 | 3 | 4 | 5 | ||
| 24 | 3 | 3 | 3 | 4 | 3 | 3 | 4 | 6 | 3 | 4 | 6 | 8 | ||
| 32 | 3 | 3 | 4 | 5 | 3 | 5 | 6 | 8 | 4 | 6 | 8 | 10 | ||
| 48 | 3 | 4 | 6 | 7 | 4 | 7 | 8 | 12 | 6 | 8 | 12 | 16 | ||
| For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 47.8 N/m2. |
| a. 40d box (5″ × 0.162″) or 16d sinker (31/4″ × 0.148″) nails are permitted to be substituted for 16d common (31/2″ × 0.16″) nails. |
| b. Nailing requirements are permitted to be reduced 25 percent if nails are clinched. |
| c. Rafter tie heel joint connections are not required where the ridge is supported by a load-bearing wall, header or ridge beam. |
| d. When intermediate support of the rafter is provided by vertical struts or purlins to a load-bearing wall, the tabulated heel joint connection requirements are permitted to be reduced proportionally to the reduction in span. |
| e. Equivalent nailing patterns are required for ceiling joist to ceiling joist lap splices. f. Connected members shall be of sufficient size to prevent splitting due to nailing. |
| g. For snow loads less than 30 pounds per square foot, the required number of nails is permitted to be reduced by multiplying by the ratio of actual snow load plus 10 divided by 40, but not less than the number required for no snow load. |
Notching at the ends of rafters or ceiling joists shall not exceed one-fourth the depth. Notches in the top or bottom of the rafter or ceiling joist shall not exceed one-sixth the depth and shall not be located in the middle one-third of the span, except that a notch not more than one-third of the depth is permitted in the top of the rafter or ceiling joist not further from the face of the support than the depth of the member. Holes bored in rafters or ceiling joists shall not be within 2 inches (51 mm) of the top and bottom and their diameter shall not exceed one-third the depth of the member.
The roof construction shall have rafter and truss ties to the wall below. Resultant uplift loads shall be transferred to the foundation using a continuous load path. The rafter or truss to wall connection shall comply with Tables 2304.10.1 and 2308.7.5.
TABLE 2308.7.5 REQUIRED RATING OF APPROVED UPLIFT CONNECTORS (pounds)a, b, c, e, f, g, h
TABLE 2308.7.5 REQUIRED RATING OF APPROVED UPLIFT CONNECTORS (pounds)a, b, c, e, f, g, h
| NOMINAL DESIGN WIND SPEED,Vasdi | ROOF SPAN (feet) | OVERHANGS (pounds/feet)d | ||||||
| 12 | 20 | 24 | 28 | 32 | 36 | 40 | ||
| 85 | -72 | -120 | -145 | -169 | -193 | -217 | -241 | -38.55 |
| 90 | -91 | -151 | -181 | -212 | -242 | -272 | -302 | -43.22 |
| 100 | -131 | -281 | -262 | -305 | -349 | -393 | -436 | -53.36 |
| 110 | -175 | -292 | -351 | -409 | -467 | -526 | -584 | -64.56 |
| For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mile per hour = 1.61 km/hr, 1 pound = 0.454 Kg, 1 pound/foot = 14.5939 N/m. |
| a. The uplift connection requirements are based on a 30-foot mean roof height located in Exposure B. For Exposure C or D and for other mean roof heights, multiply the above loads by the adjustment coefficients below. |
| Mean Roof Height (feet) | ||||||||||
| EXPOSURE | 15 | 20 | 25 | 30 | 35 | 40 | 45 | 50 | 55 | 60 |
| B | 1.00 | 1.00 | 1.00 | 1.00 | 1.05 | 1.09 | 1.12 | 1.16 | 1.19 | 1.22 |
| C | 1.21 | 1.29 | 1.35 | 1.40 | 1.45 | 1.49 | 1.53 | 1.56 | 1.59 | 1.62 |
| D | 1.47 | 1.55 | 1.61 | 1.66 | 1.70 | 1.74 | 1.78 | 1.81 | 1.84 | 1.87 |
| b. The uplift connection requirements are based on the framing being spaced 24 inches on center. Multiply by 0.67 for framing spaced 16 inches on center and multiply by 0.5 for framing spaced 12 inches on center. |
| c. The uplift connection requirements include an allowance for 10 pounds of dead load. |
| d. The uplift connection requirements do not account for the effects of overhangs. The magnitude of the above loads shall be increased by adding the overhang loads found in the table. The overhang loads are also based on framing spaced 24 inches on center. The overhang loads given shall be multiplied by the overhang projection and added to the roof uplift value in the table. |
| e. The uplift connection requirements are based upon wind loading on end zones as defined in Figure 28.6.3 of ASCE 7. Connection loads for connections located a distance of 20 percent of the least horizontal dimension of the building from the corner of the building are permitted to be reduced by multiplying the table connection value by 0.7 and multiplying the overhang load by 0.8. |
| f. For wall-to-wall and wall-to-foundation connections, the capacity of the uplift connector is permitted to be reduced by 100 pounds for each full wall above. (For example, if a 500-pound rated connector is used on the roof framing, a 400-pound rated connector is permitted at the next floor level down). |
| g. Interpolation is permitted for intermediate values of Vasd and roof spans. |
| h. The rated capacity of approved tie-down devices is permitted to include up to a 60-percent increase for wind effects where allowed by material specifications. |
| i. Vasd shall be determined in accordance with Section 1609.3.1. |
Trimmer and header rafters shall be doubled, or of lumber of equivalent cross section, where the span of the header exceeds 4 feet (1219 mm). The ends of header rafters that are more than 6 feet (1829 mm) in length shall be supported by framing anchors or rafter hangers unless bearing on a beam, partition or wall.
In buildings classified as Seismic Design Category B, C, D or E. openings in horizontal diaphragms with a dimension that is greater than 4 feet (1219 mm) shall be constructed with metal ties and blocking in accordance with this section and Figure 2308.4.4.1(1). Metal ties shall be not less than 0.058 inch [1.47 mm (16 galvanized gage)] in thickness by 11/2 inches (38 mm) in width and shall have a yield stress not less than 33,000 psi (227 Mpa). Blocking shall extend not less than the dimension of the opening in the direction of the tie and blocking. Ties shall be attached to blocking in accordance with the manufacturer's instructions but with not less than eight 16d common nails on each side of the header-joist intersection.
Purlins to support roof loads are permitted to be installed to reduce the span of rafters within allowable limits and shall be supported by struts to bearing walls. The maximum span of 2-inch by 4-inch (51 mm by 102 mm) purlins shall be 4 feet (1219 mm). The maximum span of the 2-inch by 6-inch (51 mm by 152 mm) purlin shall be 6 feet (1829 mm), but in no case shall the purlin be smaller than the supported rafter. Struts shall be not less than 2-inch by 4-inch (51 mm by 102 mm) members. The unbraced length of struts shall not exceed 8 feet (2438 mm) and the slope of the struts shall be not less than 45 degrees (0.79 rad) from the horizontal.
Roof rafters and ceiling joists shall be supported laterally to prevent rotation and lateral displacement in accordance with Section 2308.4.6 and connected to braced wall lines in accordance with Section 2308.6.7.2.
Prefabricated wood I-joists, structural glued-laminated timber and structural composite lumber shall not be notched or drilled 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.
Roof sheathing shall be in accordance with Tables 2304.8(3) and 2304.8(5) for wood structural panels, and Tables 2304.8(1) and 2304.8(2) for lumber and shall comply with Section 2304.8.2.
Joints in lumber sheathing shall occur over supports unless approved end-matched lumber is used, in which case each piece shall bear on at least two supports.
Planking shall be designed in accordance with the general provisions of this code.
In lieu of such design, 2-inch (51 mm) tongue-and groove planking is permitted in accordance with Table 2308.7.12. Joints in such planking are permitted to be randomly spaced, provided the system is applied to not less than three continuous spans, planks are center matched and end matched or splined, each plank bears on at least one support, and joints are separated by not less than 24 inches (610 mm) in adjacent pieces.
TABLE 2308.7.12 ALLOWABLE SPANS FOR 2-INCH TONGUE-AND-GROOVE DECKING
(continued)
TABLE 2308.7.12‒continued ALLOWABLE SPANS FOR 2-INCH TONGUE-AND-GROOVE DECKING
In lieu of such design, 2-inch (51 mm) tongue-and groove planking is permitted in accordance with Table 2308.7.12. Joints in such planking are permitted to be randomly spaced, provided the system is applied to not less than three continuous spans, planks are center matched and end matched or splined, each plank bears on at least one support, and joints are separated by not less than 24 inches (610 mm) in adjacent pieces.
TABLE 2308.7.12 ALLOWABLE SPANS FOR 2-INCH TONGUE-AND-GROOVE DECKING
| SPANa (feet) | LIVE LOAD (pounds per square foot) | DEFLECTION LIMIT | BENDING STRESS (f) (pounds per square inch) | MODULUS OF ELASTICITY (E) (pounds per square inch) |
| Roofs | ||||
| 4 | 20 | 1/240 1/360 | 160 | 170,000 256,000 |
| 30 | 1/240 1/360 | 210 | 256,000 384,000 | |
| 40 | 1/240 1/360 | 270 | 340,000 512,000 | |
| 4.5 | 20 | 1/240 1/360 | 200 | 242,000 305,000 |
| 30 | 1/240 1/360 | 270 | 363,000 405,000 | |
| 40 | 1/240 1/360 | 350 | 484,000 725,000 | |
| 5.0 | 20 | 1/240 1/360 | 250 | 332,000 500,000 |
| 30 | 1/240 1/360 | 330 | 495,000 742,000 | |
| 40 | 1/240 1/360 | 420 | 660,000 1,000,000 | |
| 5.5 | 20 | 1/240 1/360 | 300 | 442,000 660,000 |
| 30 | 1/240 1/360 | 400 | 662,000 998,000 | |
| 40 | 1/240 1/360 | 500 | 884,000 1,330,000 | |
| 6.0 | 20 | 1/240 1/360 | 360 | 575,000 862,000 |
| 30 | 1/240 1/360 | 480 | 862,000 1,295,000 | |
| 40 | 1/240 1/360 | 600 | 1,150,000 1,730,000 | |
(continued)
TABLE 2308.7.12‒continued ALLOWABLE SPANS FOR 2-INCH TONGUE-AND-GROOVE DECKING
| SPANa (feet) | LIVE LOAD (pounds per square foot) | DEFLECTION LIMIT | BENDING STRESS (f) (pounds per square inch) | MODULUS OF ELASTICITY (E) (pounds per square inch) |
| Roofs | ||||
| 6.5 | 20 | 1/240 1/360 | 420 | 595,000 892,000 |
| 30 | 1/240 1/360 | 560 | 892,000 1,340,000 | |
| 40 | 1/240 1/360 | 700 | 1,190,000 1,730,000 | |
| 7.0 | 20 | 1/240 1/360 | 490 | 910,000 1,360,000 |
| 30 | 1/240 1/360 | 650 | 1,370,000 2,000,000 | |
| 40 | 1/240 1/360 | 810 | 1,820,000 2,725,000 | |
| 7.5 | 20 | 1/240 1/360 | 560 | 1,125,000 1,685,000 |
| 30 | 1/240 1/360 | 750 | 1,685,000 2,530,000 | |
| 40 | 1/240 1/360 | 930 | 2,250,000 3,380,000 | |
| 8.0 | 20 | 1/240 1/360 | 640 | 1,360,000 2,040,000 |
| 30 | 1/240 1/360 | 850 | 2,040,000 3,060,000 | |
| Floors | ||||
| 4 4.5 5.0 | 40 | 1/360 | 840 950 1,060 | 1,000,000 1,300,000 1,600,000 |
| For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kN/m2, 1 pound per square inch = 0.00689 N/mm2. |
| a. Spans are based on simple beam action with 10 pounds per square foot dead load and provisions for a 300-pound concentrated load on a 12-inch width of decking. Random layup is permitted in accordance with the provisions of Section 2308.7.12. Lumber thickness is 11/2 inches nominal. |
Wood trusses shall be designed in accordance with Section 2303.4. Connection to braced wall lines shall be in accordance with Section 2308.6.7.2.
For attic ventilation, see Section 1203.2.