(a) Collar beams of one inch by six inches, or two inches by four inches, shall be installed on at least each third pair of roof rafters and shall be securely nailed to the rafters. Maximum spacing of collar beams shall be four feet on center.
Collar Beam Table | |
24 ft. wide building | 4 feet on center |
26 ft. wide building | 32 inches on center |
28 ft. wide building | 16 inches on center |
(b) In flat roof construction, when the ceiling is suspended from the roof, the spans of the roof joists shall be that required for floor joists. The ceiling joists shall be not less than two by fours of the same spacing as the roof joists and supported by not less than one-inch by four-inch hangers spaced not more than six feet on center and securely nailed to the sides of the roof and the ceiling joists.
(c) Maximum spans for roof rafters shall be as indicated unless stress grade lumber with a different stress is used.
(d) Rafters shall be securely spiked to the wall plate. Opposing rafters shall be framed directly opposite each other at the ridge. There shall be a ridge board at all ridges and a valley rafter at all valleys. The depth of the ridge board and valley rafter shall be not less than the cut end of the abutting rafters. Valley rafters shall be not less than two inches thick for spans under twelve feet and not less than four inches thick for spans over twelve feet.
(e) All openings in roof construction for dormer windows, which are not supported on partitions, shall be framed with double rafters and headers.
(f) Requirements for headers and trimmers for roof framing around chimneys shall be the same a required for floors, except that for a sloping roof where headers are less than four feet in length and the chimney is either at the ridge or at the eaves, the trimmers may be single.
(NOTE: For spans of roof rafters, refer to the Ceiling and Floor Joist tables in Section 1466.06.)
(Ord. 42-1981. Passed 2-23-81.)