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R802.5 Ceiling Joists
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Ceiling joists shall be continuous across the structure or securely joined where they meet over interior partitions in accordance with Table R802.5.2.
Ceiling joists shall be sized based on the joist spans in Tables R802.5.1(1) and R802.5.1(2). For other grades and species and for other loading conditions, refer to the AWC STJR.
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 | ||||||
| (feet - inches) | (feet - inches) | (feet - inches) | (feet - inches) | |||
| 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 | 11-1 | 16-3 | 20-7 | 25-2 | |
| 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 | 23-4 | Note a | |
| Douglas fir-larch | #3 | 9-7 | 14-1 | 17-10 | 21-9 | |
| 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 | 23-10 | 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 | |
| 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 | 16-8 | 21-4 | 26-0 | |
| Douglas fir-larch | #3 | 8-9 | 12-10 | 16-3 | 19-10 | |
| 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 | 15-0 | 19-1 | 23-3 | |
| Douglas fir-larch | #3 | 7-10 | 11-6 | 14-7 | 17-9 | |
| Hem-fir | SS | 9-10 | 15-6 | 20-5 | Note a | |
| Hem-fir | #1 | 9-8 | 15-2 | 19-10 | 24-3 | |
| 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.
- Span exceeds 26 feet in length.
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 | ||||||
| (feet - inches) | (feet - inches) | (feet - inches) | (feet - inches) | |||
| 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 | 15-0 | 19-1 | 23-3 | |
| Douglas fir-larch | #3 | 7-10 | 11-6 | 14-7 | 17-9 | |
| Hem-fir | SS | 9-10 | 15-6 | 20-5 | Note a | |
| Hem-fir | #1 | 9-8 | 15-2 | 19-10 | 24-3 | |
| 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 | 8-11 | 13-0 | 16-6 | 20-2 | |
| Douglas fir-larch | #3 | 6-10 | 9-11 | 12-7 | 15-5 | |
| Hem-fir | SS | 8-11 | 14-1 | 18-6 | 23-8 | |
| Hem-fir | #1 | 8-9 | 13-7 | 17-2 | 21-0 | |
| 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 | |
| 19.2 | Douglas fir-larch | SS | 8-11 | 14-0 | 18-5 | 23-7 |
| Douglas fir-larch | #1 | 8-7 | 12-6 | 15-10 | 19-5 | |
| Douglas fir-larch | #2 | 8-2 | 11-11 | 15-1 | 18-5 | |
| Douglas fir-larch | #3 | 6-2 | 9-1 | 11-6 | 14-1 | |
| Hem-fir | SS | 8-5 | 13-3 | 17-5 | 22-3 | |
| Hem-fir | #1 | 8-3 | 12-4 | 15-8 | 19-2 | |
| 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 | 17-2 | 21-3 |
| Douglas fir-larch | #1 | 7-8 | 11-2 | 14-2 | 17-4 | |
| Douglas fir-larch | #2 | 7-3 | 10-8 | 13-6 | 16-5 | |
| Douglas fir-larch | #3 | 5-7 | 8-1 | 10-3 | 12-7 | |
| Hem-fir | SS | 7-10 | 12-3 | 16-2 | 20-6 | |
| Hem-fir | #1 | 7-7 | 11-1 | 14-0 | 17-1 | |
| 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.
- Span exceeds 26 feet in length.
Where ceiling joists run parallel to rafters, they shall be connected to rafters at the top wall plate in accordance with Table R802.5.2. Where ceiling joists are not connected to the rafters at the top wall plate, they shall be installed in the bottom third of the rafter height in accordance with Figure R802.4.5 and Table R802.5.2. Where the ceiling joists are installed above the bottom third of the rafter height, the ridge shall be designed as a beam.Where ceiling joists do not run parallel to rafters, the ceiling joists shall be connected to top plates in accordance with Table R602.3(1). Each rafter shall be tied across the structure with a rafter tie or a 2-inch by 4-inch (51 mm × 102 mm) kicker connected to the ceiling diaphragm with nails equivalent in capacity to Table R802.5.2.
RAFTER/CEILING JOIST HEEL JOINT CONNECTIONSa, b, c, d, e, g
| RAFTER SLOPE |
RAFTER SPACING (inches) |
GROUND SNOW LOAD (psf) | |||||||||||||||
| 20f | 30 | 50 | 70 | ||||||||||||||
| Roof span (feet) | |||||||||||||||||
| 12 | 20 | 28 | 36 | 12 | 20 | 28 | 36 | 12 | 20 | 28 | 36 | 12 | 20 | 28 | 36 | ||
| Required number of 16d common nailsa, b per heel joint splicesc, d, e | |||||||||||||||||
| 3:12 | 12 | 4 | 6 | 8 | 10 | 4 | 6 | 8 | 11 | 5 | 8 | 12 | 15 | 6 | 11 | 15 | 20 |
| 16 | 5 | 8 | 10 | 13 | 5 | 8 | 11 | 14 | 6 | 11 | 15 | 20 | 8 | 14 | 20 | 26 | |
| 24 | 7 | 11 | 15 | 19 | 7 | 11 | 16 | 21 | 9 | 16 | 23 | 30 | 12 | 21 | 30 | 39 | |
| 4:12 | 12 | 3 | 5 | 6 | 8 | 3 | 5 | 6 | 8 | 4 | 6 | 9 | 11 | 5 | 8 | 12 | 15 |
| 16 | 4 | 6 | 8 | 10 | 4 | 6 | 8 | 11 | 5 | 8 | 12 | 15 | 6 | 11 | 15 | 20 | |
| 24 | 5 | 8 | 12 | 15 | 5 | 9 | 12 | 16 | 7 | 12 | 17 | 22 | 9 | 16 | 23 | 29 | |
| 5:12 | 12 | 3 | 4 | 5 | 6 | 3 | 4 | 5 | 7 | 3 | 5 | 7 | 9 | 4 | 7 | 9 | 12 |
| 16 | 3 | 5 | 6 | 8 | 3 | 5 | 7 | 9 | 4 | 7 | 9 | 12 | 5 | 9 | 12 | 16 | |
| 24 | 4 | 7 | 9 | 12 | 4 | 7 | 10 | 13 | 6 | 10 | 14 | 18 | 7 | 13 | 18 | 23 | |
| 7:12 | 12 | 3 | 4 | 4 | 5 | 3 | 3 | 4 | 5 | 3 | 4 | 5 | 7 | 3 | 5 | 7 | 9 |
| 16 | 3 | 4 | 5 | 6 | 3 | 4 | 5 | 6 | 3 | 5 | 7 | 9 | 4 | 6 | 9 | 11 | |
| 24 | 3 | 5 | 7 | 9 | 3 | 5 | 7 | 9 | 4 | 7 | 10 | 13 | 5 | 9 | 13 | 17 | |
| 9:12 | 12 | 3 | 3 | 4 | 4 | 3 | 3 | 3 | 4 | 3 | 3 | 4 | 5 | 3 | 4 | 5 | 7 |
| 16 | 3 | 4 | 4 | 5 | 3 | 3 | 4 | 5 | 3 | 4 | 5 | 7 | 3 | 5 | 7 | 9 | |
| 24 | 3 | 4 | 6 | 7 | 3 | 4 | 6 | 7 | 3 | 6 | 8 | 10 | 4 | 7 | 10 | 13 | |
| 12:12 | 12 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 4 | 3 | 3 | 4 | 5 |
| 16 | 3 | 3 | 4 | 4 | 3 | 3 | 3 | 4 | 3 | 3 | 4 | 5 | 3 | 4 | 5 | 7 | |
| 24 | 3 | 4 | 4 | 5 | 3 | 3 | 4 | 6 | 3 | 4 | 6 | 8 | 3 | 6 | 8 | 10 | |
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
- 40d box nails shall be permitted to be substituted for 16d common nails.
- Nailing requirements shall be permitted to be reduced 25 percent if nails are clinched.
- Heel joint connections are not required where the ridge is supported by a load-bearing wall, header or ridge beam.
- Where intermediate support of the rafter is provided by vertical struts or purlins to a load-bearing wall, the tabulated heel joint connection requirements shall be permitted to be reduced proportionally to the reduction in span.
- Equivalent nailing patterns are required for ceiling joist to ceiling joist lap splices.
- Applies to roof live load of 20 psf or less.
-
Tabulated heel joint connection requirements assume that ceiling joists or rafter ties are located at the bottom of the attic space. Where ceiling joists or rafter ties are located higher in the attic, heel joint connection requirements shall be increased by the following factors:
HC/HR Heel Joint Connection Adjustment Factor 1/3 1.5 1/4 1.33 1/5 1.25 1/6 1.2 1/10 or less 1.11
Ends of ceiling joists shall be lapped not less than 3 inches (76 mm) or butted over bearing partitions or beams and toenailed to the bearing member. Where ceiling joists are used to provide resistance to rafter thrust, lapped joists shall be nailed together in accordance with Table R802.5.2 and butted joists shall be tied together in a manner to resist such thrust. Joists that do not resist thrust shall be permitted to be nailed in accordance with Table R602.3(1). Wood structural panel roof sheathing, in accordance with Table R503.2.1.1(1), shall not cantilever more than 9 inches (229 mm) beyond the gable endwall unless supported by gable overhang framing.
Wood rafter ties shall be not less than 2 inches by 4 inches (51 mm × 102 mm) installed in accordance with Table R802.5.2 at each rafter. Other approved rafter tie methods shall be permitted.
Blocking shall be not less than utility grade lumber.
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