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// CODE SNIPPET

R802.5.1 Purlins

Los Angeles Residential Code > 8 Roof-Ceiling Construction > R802 Wood Roof Framing > R802.5 Allowable Rafter Spans > R802.5.1 Purlins
JUMP TO FULL CODE CHAPTER
AMENDMENT
This section has been amended at the state or city level.

Installation of purlins to reduce the span of rafters is permitted as shown in Figure R802.5.1. Purlins shall be sized not less than the required size of the rafters that they support. Purlins shall be continuous and shall be supported by 2-inch by 4-inch (51 mm by 102 mm) braces installed to bearing walls at a slope not less than 45 degrees (0.785 rad) from the horizontal. The braces shall be spaced not more than 4 feet (1219 mm) on center and the unbraced length of braces shall not exceed 8 feet (2438 mm).

TABLE R802.5.1(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 GRADEDEAD LOAD = 10 psfDEAD LOAD = 20 psf
2 × 42 × 62 × 82 × 102 × 122 × 42 × 62 × 82 × 102 × 12
Maximum rafter spansa
(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)
12Douglas fir-larchSS11-618-023-9Note bNote b11-618-023-9Note bNote b
Douglas fir-larch#111-117-422-5Note bNote b10-615-419-523-9Note b
Douglas fir-larch#210-1016-1021-426-0Note b10-014-718-522-626-0
Douglas fir-larch#38-912-1016-319-1023-07-711-114-117-219-11
Hem-firSS10-1017-022-5Note bNote b10-1017-022-5Note bNote b
Hem-fir#110-716-822-0Note bNote b10-415-219-223-5Note b
Hem-fir#210-115-1120-825-3Note b9-814-217-1121-1125-5
Hem-fir#38-712-615-1019-522-67-510-1013-916-919-6
Southern pineSS11-317-823-4Note bNote b11-317-823-4Note bNote b
Southern pine#110-1017-022-5Note bNote b10-615-819-1023-2Note b
Southern pine#210-415-719-823-5Note b9-013-617-120-323-10
Southern pine#38-011-914-1018-021-46-1110-212-1015-718-6
Spruce-pine-firSS10-716-821-11Note bNote b10-716-821-9Note bNote b
Spruce-pine-fir#110-416-321-025-8Note b9-1014-418-222-325-9
Spruce-pine-fir#210-416-321-025-8Note b9-1014-418-222-325-9
Spruce-pine-fir#38-712-615-1019-522-67-510-1013-916-919-6
16Douglas fir-larchSS10-516-421-7Note bNote b10-516-320-725-2Note b
Douglas fir-larch#110-015-419-523-9Note b9-113-316-1020-723-10
Douglas fir-larch#29-1014-718-522-626-08-712-716-019-622-7
Douglas fir-larch#37-711-114-117-219-116-79-812-1214-1117-3
Hem-firSS9-1015-620-5Note bNote b9-1015-619-1124-4Note b
Hem-fir#19-815-219-223-5Note b9-013-116-720-423-7
Hem-fir#29-214-217-1121-1125-58-512-315-618-1122-0
Hem-fir#37-510-1013-916-919-66-59-511-1114-616-10
Southern pineSS10-316-121-2Note bNote b10-316-121-225-7Note b
Southern pine#19-1015-619-1023-2Note b9-113-717-220-123-10
Southern pine#29-013-617-120-323-107-911-814-917-620-8
Southern pine#36-1110-212-1015-718-66-08-1011-213-616-0
Spruce-pine-firSS9-815-219-1125-5Note b9-814-1018-1023-0Note b
Spruce-pine-fir#19-514-418-222-325-98-612-515-919-322-4
Spruce-pine-fir#29-514-418-222-325-98-612-515-919-322-4
Spruce-pine-fir#37-510-1013-916-919-66-59-511-1114-616-10
19.2Douglas fir-larchSS9-1015-520-425-11Note b9-1014-1018-1023-0Note b
Douglas fir-larch#19-514-017-921-825-28-412-215-418-921-9
Douglas fir-larch#29-113-316-1020-723-107-1011-614-717-1020-8
Douglas fir-larch#36-1110-212-1015-818-36-08-911-212-715-9
Hem-firSS9-314-719-224-6Note b9-314-418-222-325-9
Hem-fir#19-113-1017-621-524-108-212-015-218-621-6
Hem-fir#28-812-1116-420-023-27-811-214-217-420-1
Hem-fir#36-99-1112-715-417-95-108-710-1013-315-5
Southern pineSS9-815-219-1125-5Note b9-815-219-723-4Note b
Southern pine#19-314-318-121-225-28-412-415-818-421-9
Southern pine#28-212-315-718-621-97-110-813-616-018-10
Southern pine#36-49-411-914-316-105-68-110-212-414-7
Spruce-pine-firSS9-114-318-923-11Note b9-113-717-221-024-4
Spruce-pine-fir#18-1013-116-720-323-67-911-414-417-720-4
Spruce-pine-fir#28-1013-116-720-323-67-911-414-417-720-4
Spruce-pine-fir#36-99-1112-715-417-95-108-710-1013-315-5
24Douglas fir-larchSS9-114-418-1023-9Note b9-113-316-1020-723-10
Douglas fir-larch#18-712-615-1019-522-67-510-1013-916-919-6
Douglas fir-larch#28-211-1115-118-521-47-010-413-015-1118-6
Douglas fir-larch#36-29-111-614-116-35-47-1010-012-214-1
Hem-firSS8-713-617-1022-9Note b8-712-1016-319-1023-0
Hem-fir#18-512-415-819-222-27-410-913-716-719-3
Hem-fir#27-1111-714-817-1020-96-1010-012-815-617-11
Hem-fir#36-18-1011-313-815-115-37-89-911-1013-9
Southern pineSS8-1114-118-623-8Note b8-1113-1017-620-1024-8
Southern pine#18-712-916-218-1122-67-511-114-016-519-6
Southern pine#27-411-013-1116-619-66-49-612-114-416-10
Southern pine#35-88-410-612-915-14-117-39-111-013-1
Spruce-pine-firSS8-513-317-521-825-28-412-215-418-921-9
Spruce-pine-fir#18-011-914-1018-221-06-1110-212-1015-818-3
Spruce-pine-fir#28-011-914-1018-221-06-1110-212-1015-818-3
Spruce-pine-fir#36-18-1011-313-815-115-37-89-911-1013-9

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.

  1. 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. Where ceiling joists or rafter ties are located higher in the attic space, the rafter spans shall be multiplied by the following factors:

    HC/HRRafter Span Adjustment Factor
    1/30.67
    1/40.76
    1/50.83
    1/60.90
    1/7.5 or less1.00

    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.

  2. Span exceeds 26 feet in length.

TABLE R802.5.1(2)

RAFTER SPANS FOR COMMON LUMBER SPECIES (Roof live load=20 psf, ceiling attached to rafters, L/Δ = 240)

RAFTER SPACING (inches)SPECIES AND GRADEDEAD LOAD = 10 psfDEAD LOAD = 20 psf
2 × 42 × 62 × 82 × 102 × 122 × 42 × 62 × 82 × 102 × 12
Maximum rafter spansa
(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)
12Douglas fir-larchSS10-516-421-7Note bNote b10-516-421-7Note bNote b
Douglas fir-larch#110-015-920-10Note bNote b10-015-419-523-9Note b
Douglas fir-larch#29-1015-620-526-0Note b9-1014-718-522-626-0
Douglas fir-larch#38-912-1016-319-1023-07-711-114-117-219-11
Hem-firSS9-1015-620-5Note bNote b9-1015-620-5Note bNote b
Hem-fir#19-815-219-1125-5Note b9-815-219-223-5Note b
Hem-fir#29-214-519-024-3Note b9-214-217-1121-1125-5
Hem-fir#38-712-615-1019-522-67-510-1013-916-919-6
Southern pineSS10-316-121-2Note bNote b10-316-121-2Note bNote b
Southern pine#19-1015-620-5Note bNote b9-1015-619-1023-2Note b
Southern pine#29-514-919-623-5Note b9-013-617-120-323-10
Southern pine#38-011-914-1018-021-46-1110-212-1015-718-6
Spruce-pine-firSS9-815-219-1125-5Note b9-815-219-1125-5Note b
Spruce-pine-fir#19-514-919-624-10Note b9-514-418-222-325-9
Spruce-pine-fir#29-514-919-624-10Note b9-514-418-222-325-9
Spruce-pine-fir#38-712-615-1019-522-67-510-1013-916-919-6
16Douglas fir-larchSS9-614-1119-725-0Note b9-614-1119-725-0Note b
Douglas fir-larch#19-114-418-1123-9Note b9-113-316-1020-723-10
Douglas fir-larch#28-1114-118-522-626-08-712-716-019-622-7
Douglas fir-larch#37-711-114-117-219-116-79-812-214-1117-3
Hem-firSS8-1114-118-623-8Note b8-1114-118-623-8Note b
Hem-fir#18-913-918-123-1Note b8-913-116-720-423-7
Hem-fir#28-413-117-321-1125-58-412-315-618-1122-0
Hem-fir#37-510-1013-916-919-66-59-511-1114-616-10
Southern pineSS9-414-719-324-7Note b9-414-719-324-7Note b
Southern pine#18-1114-118-623-2Note b8-1113-717-220-123-10
Southern pine#28-713-517-120-323-107-911-814-917-620-8
Southern pine#36-1110-212-1015-718-66-08-1011-213-616-0
Spruce-pine-firSS8-913-918-123-1Note b8-913-918-123-0Note b
Spruce-pine-fir#18-713-517-922-325-98-612-515-919-322-4
Spruce-pine-fir#28-713-517-922-325-98-612-515-919-322-4
Spruce-pine-fir#37-510-1013-916-919-66-59-511-1114-616-10
19.2Douglas fir-larchSS8-1114-018-523-7Note b8-1114-018-523-0Note b
Douglas fir-larch#18-713-617-921-825-28-412-215-418-921-9
Douglas fir-larch#28-513-316-1020-723-107-1011-614-717-1020-8
Douglas fir-larch#36-1110-212-1015-818-36-08-911-213-715-9
Hem-firSS8-513-317-522-3Note b8-513-317-522-325-9
Hem-fir#18-312-1117-121-524-108-212-015-218-621-6
Hem-fir#27-1012-416-320-023-27-811-214-217-420-1
Hem-fir#36-99-1112-715-417-95-108-710-1013-315-5
Southern pineSS8-913-918-223-1Note b8-913-918-223-1Note b
Southern pine#18-513-317-521-225-28-412-415-818-421-9
Southern pine#28-112-315-718-621-97-110-813-616-018-10
Southern pine#36-49-411-914-316-105-68-110-212-414-7
Spruce-pine-firSS8-312-1117-121-9Note b8-312-1117-121-024-4
Spruce-pine-fir#18-112-816-720-323-67-911-414-417-720-4
Spruce-pine-fir#28-112-816-720-323-67-911-414-417-720-4
Spruce-pine-fir#36-99-1112-715-417-95-108-710-1013-315-5
24Douglas fir-larchSS8-313-017-221-10Note b8-313-016-1020-723-10
Douglas fir-larch#18-012-615-1019-522-67-510-1013-916-919-6
Douglas fir-larch#27-1011-1115-118-521-47-010-413-015-1118-6
Douglas fir-larch#36-29-111-614-116-35-47-1010-012-214-1
Hem-firSS7-1012-316-220-825-17-1012-316-219-1023-0
Hem-fir#17-812-015-819-222-27-410-913-716-719-3
Hem-fir#27-311-514-817-1020-96-1010-012-815-617-11
Hem-fir#36-18-1011-313-815-115-37-89-911-1013-9
Southern pineSS8-112-916-1021-6Note b8-112-916-1020-1024-8
Southern pine#17-1012-316-218-1122-67-511-114-016-519-6
Southern pine#27-411-013-1116-619-66-49-612-114-416-10
Southern pine#35-88-410-612-915-14-117-39-111-013-1
Spruce-pine-firSS7-812-015-1020-224-77-812-015-418-921-9
Spruce-pine-fir#17-611-914-1018-221-06-1110-212-1015-818-3
Spruce-pine-fir#27-611-914-1018-221-06-1110-212-1015-818-3
Spruce-pine-fir#36-18-1011-313-815-115-37-89-911-1013-9

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.

  1. 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. Where ceiling joists or rafter ties are located higher in the attic space, the rafter spans shall be multiplied by the following factors:

    HC/HRRafter Span Adjustment Factor
    1/30.67
    1/40.76
    1/50.83
    1/60.90
    1/7.5 or less1.00

    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.

  2. Span exceeds 26 feet in length.

TABLE R802.5.1(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 GRADEDEAD LOAD = 10 psfDEAD LOAD = 20 psf
2 × 42 × 62 × 82 × 102 × 122 × 42 × 62 × 82 × 102 × 12
Maximum rafter spansa
(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)
12Douglas fir-larchSS10-015-920-9Note bNote b10-015-920-524-11Note b
Douglas fir-larch#19-814-918-822-9Note b9-013-216-820-423-7
Douglas fir-larch#29-614-017-821-725-18-612-615-1019-422-5
Douglas fir-larch#37-310-813-616-619-26-69-612-114-917-1
Hem-firSS9-614-1019-725-0Note b9-614-1019-724-1Note b
Hem-fir#19-314-618-522-626-08-1113-016-620-123-4
Hem-fir#28-1013-717-221-024-48-412-215-418-921-9
Hem-fir#37-110-513-216-118-86-49-411-914-516-8
Southern pineSS9-1015-620-5Note bNote b9-1015-620-525-4Note b
Southern pine#19-614-1019-022-3Note b9-013-517-019-1123-7
Southern pine#28-712-1116-419-522-107-811-714-817-420-5
Southern pine#36-79-912-415-017-95-118-911-013-515-10
Spruce-pine-firSS9-314-719-224-6Note b9-314-718-822-9Note b
Spruce-pine-fir#19-113-917-521-424-88-512-415-719-122-1
Spruce-pine-fir#29-113-917-521-424-88-512-415-719-122-1
Spruce-pine-fir#37-110-513-216-118-86-49-411-914-516-8
16Douglas fir-larchSS9-114-418-1024-1Note b9-114-017-821-725-1
Douglas fir-larch#18-912-916-219-922-107-1011-514-517-820-5
Douglas fir-larch#28-312-115-418-921-87-510-1013-816-919-5
Douglas fir-larch#36-49-311-814-316-75-88-310-612-914-10
Hem-firSS8-713-617-1022-9Note b8-713-617-120-1024-2
Hem-fir#18-512-715-1119-622-77-811-314-317-520-2
Hem-fir#28-011-914-1118-221-17-210-613-416-318-10
Hem-fir#36-29-011-513-1116-25-68-110-312-614-6
Southern pineSS8-1114-118-623-8Note b8-1114-118-51-1125-11
Southern pine#18-713-016-619-322-107-1011-714-917-320-5
Southern pine#27-611-214-216-1019-106-810-012-815-117-9
Southern pine#35-98-610-813-015-45-27-79-711-713-9
Spruce-pine-firSS8-513-317-522-125-78-512-916-219-922-10
Spruce-pine-fir#18-211-1115-118-521-57-310-813-616-619-2
Spruce-pine-fir#28-211-1115-118-521-57-310-813-616-619-2
Spruce-pine-fir#36-29-011-513-1116-25-68-110-312-614-6
19.2Douglas fir-larchSS8-713-617-922-125-78-712-916-219-922-10
Douglas fir-larch#17-1111-814-918-020-117-110-513-216-118-8
Douglas fir-larch#27-711-014-017-119-106-99-1012-615-317-9
Douglas fir-larch#35-98-510-813-115-25-27-79-711-813-6
Hem-firSS8-112-916-921-424-88-112-415-719-122-1
Hem-fir#17-1011-614-717-920-77-010-313-015-1118-5
Hem-fir#27-410-913-716-719-36-79-712-214-1017-3
Hem-fir#35-78-310-512-914-95-07-49-411-513-2
Southern pineSS8-513-317-522-3Note b8-513-316-1020-023-7
Southern pine#18-011-1015-117-720-117-110-713-515-918-8
Southern pine#26-1010-212-1115-418-16-19-211-713-916-2
Southern pine#35-37-99-911-1014-04-86-118-910-712-6
Spruce-pine-firSS7-1112-516-520-223-47-1111-814-918-020-11
Spruce-pine-fir#17-510-1113-916-1019-66-89-912-415-117-6
Spruce-pine-fir#27-510-1113-916-1019-66-89-912-415-117-6
Spruce-pine-fir#35-78-310-512-914-95-07-49-411-513-2
24Douglas fir-larchSS8-012-616-219-922-107-1011-514-517-820-5
Douglas fir-larch#17-110-513-216-118-86-49-411-914-516-8
Douglas fir-larch#26-99-1012-615-317-96-08-1011-213-815-10
Douglas fir-larch#35-27-79-711-813-64-76-98-710-512-1
Hem-firSS7-611-1015-719-122-17-611-013-1117-019-9
Hem-fir#17-010-313-015-1118-56-39-211-814-316-6
Hem-fir#26-79-712-214-1017-35-108-710-1013-315-5
Hem-fir#35-07-49-411-513-24-66-78-410-211-10
Southern pineSS7-1012-316-220-023-77-1011-1015-017-1121-2
Southern pine#17-110-713-515-918-86-49-612-014-116-8
Southern pine#26-19-211-713-916-25-58-210-412-314-6
Southern pine#34-86-118-910-712-64-26-27-109-611-2
Spruce-pine-firSS7-411-714-918-020-117-110-513-216-118-8
Spruce-pine-fir#16-89-912-415-117-65-118-811-013-615-7
Spruce-pine-fir#26-89-912-415-117-65-118-811-013-615-7
Spruce-pine-fir#35-07-49-411-513-24-66-78-410-211-10

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.

  1. 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/HRRafter Span Adjustment Factor
    1/30.67
    1/40.76
    1/50.83
    1/60.90
    1/7.5 or less1.00

    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.

  2. Span exceeds 26 feet in length.

TABLE R802.5.1(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 GRADEDEAD LOAD = 10 psfDEAD LOAD = 20 psf
2 × 42 × 62 × 82 × 102 × 122 × 42 × 62 × 82 × 102 × 12
Maximum rafter spansa
(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)
12Douglas fir-larchSS8-513-317-622-426-08-513-317-321-124-5
Douglas fir-larch#18-212-015-318-721-77-711-214-117-320-0
Douglas fir-larch#27-1011-514-517-820-57-310-713-416-418-11
Douglas fir-larch#36-08-911-013-615-75-68-110-312-614-6
Hem-firSS8-012-616-621-125-68-012-616-620-423-7
Hem-fir#17-1011-1015-018-421-37-611-013-1117-019-9
Hem-fir#27-511-114-017-219-117-010-313-015-1018-5
Hem-fir#35-108-610-913-215-35-57-1010-012-214-1
Southern pineSS8-413-117-221-11Note b8-413-117-221-525-3
Southern pine#18-012-315-618-221-77-711-414-516-1020-0
Southern pine#27-010-613-415-1018-86-69-912-414-817-3
Southern pine#35-58-010-112-314-65-07-59-411-413-5
Spruce-pine-firSS7-1012-316-220-824-17-1012-315-919-322-4
Spruce-pine-fir#17-811-314-317-520-27-110-513-216-118-8
Spruce-pine-fir#27-811-314-317-520-27-110-513-216-118-8
Spruce-pine-fir#35-108-610-913-215-35-57-1010-012-214-1
16Douglas fir-larchSS7-812-115-1119-922-107-811-1014-1118-321-2
Douglas fir-larch#17-110-513-216-118-86-79-812-214-1117-3
Douglas fir-larch#26-99-1012-615-317-96-39-211-714-216-5
Douglas fir-larch#35-27-79-711-1813-64-97-08-1010-1012-6
Hem-firSS7-311-515-019-122-17-311-514-517-820-5
Hem-fir#17-010-313-015-1118-56-69-612-114-917-1
Hem-fir#26-79-712-214-1017-36-18-1111-313-915-11
Hem-fir#35-07-49-411-513-24-86-108-810-612-3
Southern pineSS7-611-1015-719-1123-77-611-1015-718-621-10
Southern pine#17-110-713-515-918-86-79-1012-514-717-3
Southern pine#26-19-211-713-916-25-88-510-912-915-0
Southern pine#34-86-118-910-712-64-46-58-19-1011-7
Spruce-pine-firSS7-111-214-818-020-117-110-913-815-1119-4
Spruce-pine-fir#16-89-912-415-117-66-29-011-513-1116-2
Spruce-pine-fir#26-89-912-415-117-66-29-011-513-1116-2
Spruce-pine-fir#35-07-49-411-513-24-86-108-810-612-3
19.2Douglas fir-larchSS7-311-414-918-020-117-310-913-816-819-4
Douglas fir-larch#16-69-612-014-817-16-08-1011-213-715-9
Douglas fir-larch#26-29-011-513-1116-25-88-410-912-1115-0
Douglas fir-larch#34-86-118-910-812-44-46-48-19-1011-5
Hem-firSS6-1010-914-217-520-26-1010-513-216-118-8
Hem-fir#16-59-511-1114-616-108-118-811-013-515-7
Hem-fir#26-08-911-113-715-95-78-110-312-714-7
Hem-fir#34-76-98-610-512-14-36-37-119-711-2
Southern pineSS7-111-214-818-321-77-111-214-216-1120-0
Southern pine#16-69-812-314-417-16-09-011-413-415-9
Southern pine#25-78-410-712-614-95-27-99-911-713-8
Southern pine#34-36-48-09-811-54-05-107-48-1110-7
Spruce-pine-firSS6-810-613-516-519-16-89-1012-515-317-8
Spruce-pine-fir#16-18-1111-313-915-115-78-310-512-914-9
Spruce-pine-fir#26-18-1111-313-915-115-78-310-512-914-9
Spruce-pine-fir#34-76-98-610-512-14-36-37-119-711-2
24Douglas fir-larchSS6-810-513-216-118-86-79-812-214-1117-3
Douglas fir-larch#15-108-610-913-215-35-57-1010-012-214-1
Douglas fir-larch#25-68-110-312-614-65-17-69-511-713-5
Douglas fir-larch#34-36-27-109-611-13-115-87-38-1010-3
Hem-firSS6-49-1112-915-718-06-49-411-914-516-8
Hem-fir#15-98-510-813-015-18-47-99-1012-013-11
Hem-fir#25-47-109-1112-114-14-117-39-211-313-0
Hem-fir#34-16-07-79-410-93-105-77-18-710-0
Southern pineSS6-710-413-816-419-36-710-012-815-217-10
Southern pine#15-108-811-012-1015-35-58-010-211-1114-1
Southern pine#25-07-59-511-313-24-76-118-910-512-3
Southern pine#33-105-87-18-810-33-65-36-78-09-6
Spruce-pine-firSS6-29-612-014-817-16-08-1011-213-715-9
Spruce-pine-fir#15-57-1110-112-414-35-07-49-411-513-2
Spruce-pine-fir#25-57-1110-112-414-35-07-49-411-513-2
Spruce-pine-fir#34-16-07-79-410-93-105-77-18-710-0

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

  1. 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/HRRafter Span Adjustment Factor
    1/30.67
    1/40.76
    1/50.83
    1/60.90
    1/7.5 or less1.00

    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.

  2. Span exceeds 26 feet in length.

TABLE R802.5.1(5)

RAFTER SPANS FOR COMMON LUMBER SPECIES (Ground snow load=30 psf, ceiling attached to rafters, L/Δ = 240)

RAFTER SPACING (inches)SPECIES AND GRADEDEAD LOAD = 10 psfDEAD LOAD = 20 psf
2 × 42 × 62 × 82 × 102 × 122 × 42 × 62 × 82 × 102 × 12
Maximum rafter spansa
(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)
12Douglas fir-larchSS9-114-418-1024-1Note b9-114-418-1024-1Note b
Douglas fir-larch#18-913-918-222-9Note b8-913-216-820-423-7
Douglas fir-larch#28-713-617-821-725-18-612-615-1019-422-5
Douglas fir-larch#37-310-813-616-619-26-69-612-114-917-1
Hem-firSS8-713-617-1022-9Note b8-713-617-1022-9Note b
Hem-fir#18-513-317-522-326-08-513-016-620-123-4
Hem-fir#28-012-716-721-024-48-012-215-418-921-9
Hem-fir#37-110-513-216-118-86-49-411-914-516-8
Southern pineSS8-1114-118-623-8Note b8-1114-118-623-8Note b
Southern pine#18-713-617-1022-3Note b8-713-517-019-1123-7
Southern pine#28-312-1116-419-522-107-811-714-817-420-5
Southern pine#36-79-912-415-017-95-118-911-013-515-10
Spruce-pine-firSS8-513-317-522-3Note b8-513-317-522-3Note b
Spruce-pine-fir#18-312-1117-021-424-88-312-415-719-122-1
Spruce-pine-fir#28-312-1117-021-424-88-312-415-719-122-1
Spruce-pine-fir#37-110-513-216-118-86-49-411-914-516-8
16Douglas fir-larchSS8-313-017-221-10Note b8-313-017-221-725-1
Douglas fir-larch#18-012-616-219-922-107-1011-514-517-820-5
Douglas fir-larch#27-1012-115-418-921-87-510-1013-816-919-5
Douglas fir-larch#36-49-311-814-316-75-88-310-612-914-10
Hem-firSS7-1012-316-220-825-17-1012-316-220-824-2
Hem-fir#17-812-015-1019-622-77-811-314-317-520-2
Hem-fir#27-311-514-1118-221-17-210-613-416-318-10
Hem-fir#36-29-011-513-1116-25-68-110-312-614-6
Southern pineSS8-112-916-1021-6Note b8-112-916-1021-625-11
Southern pine#17-1012-316-219-322-107-1011-714-917-320-5
Southern pine#27-611-214-216-1019-106-810-012-815-117-9
Southern pine#35-98-610-813-015-45-27-79-711-713-9
Spruce-pine-firSS7-812-015-1020-224-77-812-015-1019-922-10
Spruce-pine-fir#17-611-915-118-521-57-310-813-616-619-2
Spruce-pine-fir#27-611-915-118-521-57-310-813-616-619-2
Spruce-pine-fir#36-29-011-513-1116-25-68-110-312-614-6
19.2Douglas fir-larchSS7-912-316-120-725-07-912-316-119-922-10
Douglas fir-larch#17-611-814-918-020-117-110-513-216-118-8
Douglas fir-larch#27-411-014-017-119-106-99-112-615-317-9
Douglas fir-larch#35-98-510-813-115-25-27-79-711-813-6
Hem-firSS7-411-715-319-523-77-411-715-319-122-1
Hem-fir#17-211-414-717-920-77-016-313-015-1118-5
Hem-fir#26-1010-913-716-719-36-79-712-214-1017-3
Hem-fir#35-78-310-512-914-95-07-49-411-513-2
Southern pineSS7-812-015-1020-224-77-812-015-1020-023-7
Southern pine#17-411-715-117-720-117-110-713-515-918-8
Southern pine#26-1010-212-1115-418-16-19-211-713-916-2
Southern pine#35-37-99-911-1014-04-86-118-910-712-6
Spruce-pine-firSS7-211-414-1119-023-17-211-414-918-020-11
Spruce-pine-fir#17-010-1113-916-1019-66-89-912-415-117-6
Spruce-pine-fir#27-010-1113-916-1019-66-89-912-415-117-6
Spruce-pine-fir#35-78-310-512-914-95-07-49-411-513-2
24Douglas fir-larchSS7-311-415-019-122-107-311-414-517-820-5
Douglas fir-larch#17-010-513-216-118-86-49-411-914-516-8
Douglas fir-larch#26-99-1012-615-317-96-08-1011-213-815-10
Douglas fir-larch#35-27-79-711-813-64-76-98-710-512-1
Hem-firSS6-1010-914-218-021-116-1010-913-1117-019-9
Hem-fir#16-810-313-015-1118-56-39-211-814-316-6
Hem-fir#26-49-712-214-1017-35-108-710-1013-315-5
Hem-fir#35-07-49-411-513-24-66-78-410-211-10
Southern pineSS7-111-214-818-922-107-111-214-817-1121-2
Southern pine#16-1010-713-515-918-86-49-612-014-116-8
Southern pine#26-19-211-713-916-25-58-210-412-314-6
Southern pine#34-86-118-910-712-64-26-27-109-611-2
Spruce-pine-firSS6-810-613-1017-820-116-810-513-216-118-8
Spruce-pine-fir#16-69-912-415-117-65-118-811-013-615-7
Spruce-pine-fir#26-69-912-415-117-65-118-811-013-615-7
Spruce-pine-fir#35-07-49-411-513-24-66-78-410-211-10

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.

  1. 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/HRRafter Span Adjustment Factor
    1/30.67
    1/40.76
    1/50.83
    1/60.90
    1/7.5 or less1.00

    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.

  2. Span exceeds 26 feet in length.

TABLE R802.5.1(6)

RAFTER SPANS FOR COMMON LUMBER SPECIES (Ground snow load=50 psf, ceiling attached to rafters, L/Δ = 240)

RAFTER SPACING (inches)SPECIES AND GRADEDEAD LOAD = 10 psfDEAD LOAD = 20 psf
2 × 42 × 62 × 82 × 102 × 122 × 42 × 62 × 82 × 102 × 12
Maximum rafter spansa
(feet-inches)(feet-inches)(feet-inches)(feet-inches)(feet-inches)(feet-inches)(feet-inches)(feet-inches)(feet-inches)(feet-inches)
12Douglas fir-larchSS7-812-115-1120-324-87-812-115-1120-324-5
Douglas fir-larch#17-511-715-318-721-77-511-214-117-320-0
Douglas fir-larch#27-311-514-517-820-57-310-713-416-418-11
Douglas fir-larch#36-08-911-013-615-75-68-110-312-614-6
Hem-firSS7-311-515-019-223-47-311-515-019-223-4
Hem-fir#17-111-214-818-421-37-111-013-1117-019-9
Hem-fir#26-910-814-017-219-116-910-313-015-1018-5
Hem-fir#35-108-610-913-215-35-57-1010-012-214-1
Southern pineSS7-611-1015-719-1124-37-611-1015-719-1124-3
Southern pine#17-311-515-018-221-77-311-414-516-1020-0
Southern pine#26-1110-613-415-1018-86-69-912-414-817-3
Southern pine#35-58-010-112-314-65-07-59-411-413-5
Spruce-pine-firSS7-111-214-818-922-107-111-214-818-922-4
Spruce-pine-fir#16-1110-1114-317-520-26-1110-513-216-118-8
Spruce-pine-fir#26-1110-1114-317-520-26-1110-513-216-118-8
Spruce-pine-fir#35-108-610-913-215-35-57-1010-012-214-1
16Douglas fir-larchSS7-011-014-518-522-57-011-014-518-321-2
Douglas fir-larch#16-910-513-216-118-86-79-812-214-1117-3
Douglas fir-larch#26-79-1012-615-317-96-39-211-714-216-5
Douglas fir-larch#35-27-79-711-813-64-97-08-1010-1012-6
Hem-firSS6-710-413-817-521-26-710-413-817-520-5
Hem-fir#16-510-213-015-1118-56-59-612-114-917-1
Hem-fir#26-29-712-214-1017-36-18-1111-313-915-11
Hem-fir#35-07-49-411-513-24-86-108-810-612-3
Southern pineSS6-1010-914-218-122-06-1010-914-218-121-10
Southern pine#16-710-413-515-918-86-79-1012-514-717-3
Southern pine#26-19-211-713-916-25-88-510-912-915-0
Southern pine#34-86-118-910-712-64-46-58-19-1011-7
Spruce-pine-firSS6-510-213-417-020-96-510-213-416-819-4
Spruce-pine-fir#16-49-912-415-117-66-29-011-513-1116-2
Spruce-pine-fir#26-49-912-415-117-66-29-011-513-1116-2
Spruce-pine-fir#35-07-49-411-513-24-86-108-810-612-3
19.2Douglas fir-larchSS6-710-413-717-420-116-710-413-716-819-4
Douglas fir-larch#16-49-612-014-817-16-08-1011-213-715-9
Douglas fir-larch#26-29-011-513-1116-25-88-410-712-1115-0
Douglas fir-larch#34-86-118-910-812-44-46-48-19-1011-5
Hem-firSS6-29-912-1016-519-116-29-912-1016-118-8
Hem-fir#16-19-511-1114-616-105-118-811-013-515-7
Hem-fir#25-98-911-113-715-95-78-110-312-714-7
Hem-fir#34-76-98-610-512-14-36-37-119-711-2
Southern pineSS6-510-213-417-020-96-510-213-416-1120-0
Southern pine#16-29-812-314-417-16-09-011-413-415-9
Southern pine#25-78-410-712-614-95-27-99-911-713-8
Southern pine#34-36-48-09-811-54-05-107-48-1110-7
Spruce-pine-firSS6-19-612-716-019-16-19-612-515-317-8
Spruce-pine-fir#15-118-1111-313-915-115-78-310-512-914-9
Spruce-pine-fir#25-118-1111-313-915-115-78-310-512-914-9
Spruce-pine-fir#34-76-98-610-512-14-36-37-119-711-2
24Douglas fir-larchSS6-19-712-716-118-86-19-712-214-1117-3
Douglas fir-larch#15-108-610-913-215-35-57-1010-012-214-1
Douglas fir-larch#25-68-110-312-614-65-17-69-511-713-5
Douglas fir-larch#34-36-27-109-611-13-115-87-38-1010-3
Hem-firSS5-99-111-1115-218-05-99-111-914-515-11
Hem-fir#15-88-510-813-015-15-47-99-1012-013-11
Hem-fir#25-47-109-1112-114-14-117-39-211-313-0
Hem-fir#34-16-07-79-410-93-105-77-18-710-0
Southern pineSS6-09-512-515-1019-36-09-512-515-217-10
Southern pine#15-98-811-012-1015-35-58-010-211-1114-1
Southern pine#25-07-59-511-313-24-76-118-910-512-3
Southern pine#33-105-87-18-810-33-65-36-78-09-6
Spruce-pine-firSS5-88-1011-814-817-15-88-1011-213-715-9
Spruce-pine-fir#15-57-1110-112-414-35-07-49-411-513-2
Spruce-pine-fir#25-57-1110-112-414-35-07-49-411-513-2
Spruce-pine-fir#34-16-07-79-410-93-105-77-18-710-0

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.

  1. 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/HRRafter Span Adjustment Factor
    1/30.67
    1/40.76
    1/50.83
    1/60.90
    1/7.5 or less1.00

    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.

TABLE R802.5.1(7)

RAFTER SPANS FOR 70 PSF GROUND SNOW LOAD (Ceiling not attached to rafters, L/Δ = 180)

RAFTER SPACING (inches)SPECIES AND GRADEDEAD LOAD = 10 psfDEAD LOAD = 20 psf
2 × 42 × 62 × 82 × 102 × 122 × 42 × 62 × 82 × 102 × 12
Maximum Rafter Spansa
(feet-inches)(feet-inches)(feet-inches)(feet-inches)(feet-inches)(feet-inches)(feet-inches)(feet-inches)(feet-inches)(feet-inches)
12Douglas fir-larchSS7-711-1015-819-922-107-711-1015-318-721-7
Douglas fir-larch#17-110-513-216-118-86-89-1012-515-217-7
Douglas fir-larch#26-99-1012-615-317-96-49-411-914-516-8
Douglas fir-larch#35-27-79-711-813-64-107-19-011-012-9
Hem-firSS7-211-314-918-1022-17-211-314-818-020-10
Hem-fir#17-010-313-015-1118-56-79-812-315-017-5
Hem-fir#26-79-712-214-1017-36-29-111-514-016-3
Hem-fir#35-07-49-411-513-24-96-118-910-912-5
Southern pineSS7-511-815-419-723-77-511-815-418-1022-3
Southern pine#17-110-713-515-918-86-910-012-814-1017-7
Southern pine#26-19-211-713-916-25-98-710-1112-1115-3
Southern pine#34-86-118-910-712-64-56-68-310-011-10
Spruce-pine-firSS7-011-014-618-020-117-011-013-1117-019-8
Spruce-pine-fir#16-89-912-415-117-66-39-211-814-216-6
Spruce-pine-fir#26-89-912-415-117-66-39-211-814-216-6
Spruce-pine-fir#35-07-49-411-513-24-96-118-910-912-5
16Douglas fir-larchSS6-1010-914-017-119-106-1010-513-216-118-8
Douglas fir-larch#16-29-011-513-1116-25-108-610-913-215-3
Douglas fir-larch#25-108-710-1013-315-45-68-110-312-614-6
Douglas fir-larch#34-66-68-310-111-94-36-27-109-611-1
Hem-firSS6-610-213-516-619-26-610-112-915-718-0
Hem-fir#16-18-1111-313-916-05-98-510-813-015-1
Hem-fir#25-88-410-612-1014-115-47-109-1112-114-1
Hem-fir#34-46-48-19-1011-54-16-07-79-410-9
Southern pineSS6-910-714-017-420-56-910-713-916-419-3
Southern pine#16-29-211-813-816-25-108-811-012-1015-3
Southern pine#25-37-1110-011-1114-05-07-59-511-313-2
Southern pine#34-16-07-79-210-103-105-87-18-810-3
Spruce-pine-firSS6-410-012-915-718-16-49-612-014-817-1
Spruce-pine-fir#15-98-510-813-115-25-57-1110-112-414-3
Spruce-pine-fir#25-98-510-813-115-25-57-1110-112-414-3
Spruce-pine-fir#34-46-48-19-1011-54-16-07-79-410-9
19.2Douglas fir-larchSS6-610-112-915-718-16-69-612-014-817-1
Douglas fir-larch#15-78-310-512-914-95-47-99-1012-013-11
Douglas fir-larch#25-47-109-1112-114-05-07-49-411-513-2
Douglas fir-larch#34-16-07-79-310-83-105-77-18-810-1
Hem-firSS6-19-712-415-117-46-19-211-814-215-5
Hem-fir#15-78-210-312-714-75-37-89-811-1013-9
Hem-fir#25-27-79-711-913-74-117-29-111-112-10
Hem-fir#34-05-107-49-010-53-95-66-118-69-10
Southern pineSS6-410-013-215-1018-86-49-1012-614-1117-7
Southern pine#15-88-510-812-514-95-47-1110-011-913-11
Southern pine#24-107-39-210-1012-94-66-108-810-312-1
Southern pine#33-85-66-118-49-113-65-26-67-119-4
Spruce-pine-firSS6-09-211-814-316-65-118-811-013-515-7
Spruce-pine-fir#15-37-89-911-1113-105-07-39-211-313-0
Spruce-pine-fir#25-37-89-911-1113-105-07-39-211-313-0
Spruce-pine-fir#34-05-107-49-010-53-95-66-118-69-10
24Douglas fir-larchSS6-09-011-513-1116-25-108-610-913-215-3
Douglas fir-larch#15-07-49-411-513-24-96-118-910-912-5
Douglas fir-larch#24-97-08-1010-1012-64-66-78-410-211-10
Douglas fir-larch#33-85-46-98-39-73-55-06-47-99-10
Hem-firSS5-88-811-013-613-115-78-310-512-412-4
Hem-fir#15-07-39-211-313-04-86-108-810-712-4
Hem-fir#24-86-98-710-612-24-46-58-19-1111-6
Hem-fir#33-75-26-78-19-43-44-116-37-78-10
Southern pineSS5-119-311-1114-216-85-118-1011-213-415-9
Southern pine#15-07-69-611-113-24-97-19-010-612-5
Southern pine#24-46-58-29-911-54-16-17-99-210-9
Southern pine#33-44-116-27-68-103-14-75-107-18-4
Spruce-pine-firSS5-68-310-512-914-95-47-99-1012-012-11
Spruce-pine-fir#14-86-118-910-812-44-56-68-310-011-8
Spruce-pine-fir#24-86-118-910-812-44-56-68-310-011-8
Spruce-pine-fir#33-75-26-78-19-43-44-116-37-78-10

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.

  1. 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/HRRafter Span Adjustment Factor
    1/30.67
    1/40.76
    1/50.83
    1/60.90
    1/7.5 or less1.00

    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.

TABLE R802.5.1(8)

RAFTER SPANS FOR 70 PSF GROUND SNOW LOAD (Ceiling attached to rafters, L/Δ = 240)

RAFTER SPACING (inches)SPECIES AND GRADEDEAD LOAD = 10 psfDEAD LOAD = 20 psf
2 × 42 × 62 × 82 × 102 × 122 × 42 × 62 × 82 × 102 × 12
Maximum rafter spansa
(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)(feet - inches)
12Douglas fir-larchSS6-1010-914-318-222-16-1010-914-318-221-7
Douglas fir-larch#16-710-513-216-118-86-79-1012-515-217-7
Douglas fir-larch#26-69-1012-615-317-96-49-411-914-516-8
Douglas fir-larch#35-27-79-711-813-64-107-19-011-012-9
Hem-firSS6-610-213-517-220-106-610-213-517-220-10
Hem-fir#16-410-013-015-1118-56-49-812-315-017-5
Hem-fir#26-19-612-214-1017-36-19-111-514-016-3
Hem-fir#35-07-49-411-513-24-96-118-910-912-5
Southern pineSS6-910-714-017-1021-86-910-714-017-1021-8
Southern pine#16-610-213-515-918-86-610-012-814-1017-7
Southern pine#26-19-211-713-916-25-98-710-1112-1115-3
Southern pine#34-86-118-910-712-64-56-68-310-011-10
Spruce-pine-firSS6-410-013-216-920-56-410-013-216-919-8
Spruce-pine-fir#16-29-912-415-117-66-29-211-814-216-6
Spruce-pine-fir#26-29-912-415-117-66-29-211-814-216-6
Spruce-pine-fir#35-07-49-411-513-24-96-118-910-912-5
16Douglas fir-larchSS6-39-1012-1116-619-106-39-1012-1116-118-8
Douglas fir-larch#16-09-011-513-1116-25-108-610-913-215-3
Douglas fir-larch#25-108-710-1013-315-45-68-110-312-614-6
Douglas fir-larch#34-66-68-310-111-94-36-27-109-611-1
Hem-firSS5-119-312-215-718-115-119-312-215-718-0
Hem-fir#15-98-1111-313-916-05-98-510-813-015-1
Hem-fir#25-68-410-612-1014-115-47-109-1112-114-1
Hem-fir#34-46-48-19-1011-54-16-07-79-410-9
Southern pineSS6-19-712-816-219-86-19-712-816-219-3
Southern pine#15-119-211-813-816-25-108-811-012-1015-3
Southern pine#25-37-1110-011-1114-05-07-59-511-313-2
Southern pine#34-16-07-79-210-103-105-87-18-810-3
Spruce-pine-firSS5-99-111-1115-318-15-99-111-1114-817-1
Spruce-pine-fir#15-88-510-813-115-25-57-1110-112-414-3
Spruce-pine-fir#25-88-510-813-115-25-57-1110-112-414-3
Spruce-pine-fir#34-46-48-19-1011-54-16-07-79-410-9
19.2Douglas fir-larchSS5-109-312-215-618-15-109-312-014-817-1
Douglas fir-larch#15-78-310-512-914-95-47-99-1012-013-11
Douglas fir-larch#25-47-109-1112-114-05-07-49-411-513-2
Douglas fir-larch#34-16-07-79-310-83-105-77-18-810-1
Hem-firSS5-68-811-614-817-45-68-811-614-215-5
Hem-fir#15-58-210-312-714-75-37-89-811-1013-9
Hem-fir#25-27-79-711-913-74-117-29-111-112-10
Hem-fir#34-05-107-49-010-53-95-66-118-69-10
Southern pineSS5-99-111-1115-318-65-99-111-1114-1117-7
Southern pine#15-68-510-812-514-95-47-1110-011-913-11
Southern pine#24-107-39-210-1012-94-66-108-810-312-1
Southern pine#33-85-66-118-49-113-65-26-67-119-4
Spruce-pine-firSS5-58-611-314-316-65-58-611-013-515-7
Spruce-pine-fir#15-37-89-911-1113-105-07-39-211-313-0
Spruce-pine-fir#25-37-89-911-1113-105-07-39-211-313-0
Spruce-pine-fir#34-05-107-49-010-53-95-66-118-69-10
24Douglas fir-larchSS5-58-711-313-1116-25-58-610-913-215-3
Douglas fir-larch#15-07-49-411-513-24-96-118-910-912-5
Douglas fir-larch#24-97-08-1010-1012-64-66-78-410-211-10
Douglas fir-larch#33-85-46-98-39-73-55-06-47-99-0
Hem-firSS5-28-110-813-613-115-28-110-512-412-4
Hem-fir#15-07-39-211-313-04-86-108-810-712-4
Hem-fir#24-86-98-710-612-24-46-58-19-1111-6
Hem-fir#33-75-26-78-19-43-44-116-37-78-10
Southern pineSS5-48-511-114-216-85-48-511-113-415-9
Southern pine#15-07-69-611-113-24-97-19-010-612-5
Southern pine#24-46-58-29-911-54-16-17-99-210-9
Southern pine#33-44-116-27-68-103-14-75-107-18-4
Spruce-pine-firSS5-07-1110-512-914-95-07-99-1012-012-11
Spruce-pine-fir#14-86-118-910-812-44-56-68-310-011-8
Spruce-pine-fir#24-86-118-910-812-44-56-68-310-011-8
Spruce-pine-fir#33-75-26-78-19-43-44-116-37-78-10

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.

  1. 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/HRRafter Span Adjustment Factor
    1/30.67
    1/40.76
    1/50.83
    1/60.90
    1/7.5 or less1.00

    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.

TABLE R802.5.1(9)91.5.802.5.1(9)

RAFTER/CEILING JOIST HEEL JOINT CONNECTIONSa, b, c, d, e, f, h

RAFTER SLOPERAFTER SPACING (inches)GROUND SNOW LOAD (psf)
20g305070
Roof span (feet)
12202836122028361220283612202836
Required number of 16d common nailsa, b per heel joint splicesc, d, e, f
3:121246810468115812156111520
1658101358111461115208142026
2471115197111621916233012213039
4:12123568356846911581215
1646810468115812156111520
2458121559121671217229162329
5:121234563457357947912
163568357947912591216
244791247101361014187131823
7:12123445334534573579
1634563456357946911
2435793579471013591317
9:12123344333433453457
163445334534573579
243467346736810471013
12:12123333333333343345
163344333433453457
2434453346346836810

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.

  1. 40d box nails shall be permitted to be substituted for 16d common nails.
  2. Nailing requirements shall be permitted to be reduced 25 percent if nails are clinched.
  3. Heel joint connections are not required where when the ridge is supported by a load-bearing wall, header or ridge beam.
  4. Where intermediate When immediate 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.
  5. Equivalent nailing patterns are required for ceiling joists to ceiling joist lap splices.
  6. Where When rafter ties are substituted for ceiling joists, the heel joint connection requirement shall be taken as the tabulated heel joint connection requirement for two-thirds of the actual rafter slope.
  7. Applies to roof live load of 20 psf or less.
  8. Tabulated heel joint connection requirements assume that ceiling joists or rafter ties are located at the bottom of the attic space. WhereWhen ceiling joists or rafter ties are located higher in the attic, heel joint connection requirements shall be increased by the following factors:


    HC/HRHeel Joint Connection Adjustment Factor
    1/31.5
    1/41.33
    1/51.25
    1/61.2
    1/10 or less1.11

    where:

    HC = Height of ceiling joists or rafter ties measured vertically above the top of the rafter support walls.

    HR = Height of the roof ridge measured vertically above the top of the rafter support walls.

  9. Edge distances, end distances and spacing for nails shall be sufficient to prevent splitting of the wood.

For SI: 1 inch = 25.4 mm, 1 foot = 305 mm, 1 degree = 0.018 rad.

Note: Where ceiling joists run perpendicular to the rafter, rafter ties shall be installed in accordance with Section R802.3.1.

HC = Height of ceiling joists or rafter ties measured vertically above the top of rafter support walls.

HR = Height of roof ridge measured vertically above the top of the rafter support walls.

FIGURE R802.5.1

BRACED RAFTER CONSTRUCTION

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