Section R804 Cold-Formed Steel Roof Framing
- The maximum tolerance shall be 3/4 inch (19.1 mm) between the centerline of the horizontal framing member and the centerline of the vertical framing member.
- Where the centerline of the horizontal framing member and bearing stiffener are located to one side of the centerline of the vertical framing member, the maximum tolerance shall be 1/8 inch (3.2 mm) between the web of the horizontal framing member and the edge of the vertical framing member.
Load-bearing, cold-formed steel framing shall have a metallic coating complying with ASTM A1003 and one of the following:
- Not less than G 60 in accordance with ASTM A653.
- Not less than AZ 50 in accordance with ASTM A792.
Load-bearing, cold-formed steel roof framing members shall comply with Figure R804.2.3(1) and with the dimensional and thickness requirements specified in Table R804.2.3. Additionally, C-shaped sections shall have a minimum flange width of 1.625 inches (41 mm) and a maximum flange width of 2 inches (51 mm). The minimum lip size for C-shaped sections shall be 1/2 inch (12.7 mm). Tracks shall comply with Figure R804.2.3(2) and shall have a minimum flange width of 11/4 inches (32 mm). Minimum Grade 33 ksi steel shall be used wherever 33 mil and 43 mil thicknesses are specified. Minimum Grade 50 ksi steel shall be used wherever 54 and 68 mil thicknesses are specified.
LOAD-BEARING COLD-FORMED STEEL ROOF FRAMING MEMBER SIZES AND THICKNESSES
|WEB DEPTH |
|MINIMUM BASE STEEL THICKNESS |
|350S162-t||3.5||33 (0.0329), 43 (0.0428), 54 (0.0538)|
|550S162-t||5.5||33 (0.0329), 43 (0.0428), 54 (0.0538), 68 (0.0677)|
|800S162-t||8||33 (0.0329), 43 (0.0428), 54 (0.0538), 68 (0.0677)|
|1000S162-t||10||43 (0.0428), 54 (0.0538), 68 (0.0677)|
|1200S162-t||12||43 (0.0428), 54 (0.0538), 68 (0.0677)|
For SI: 1 inch = 25.4 mm
- The member designation is defined by the first number representing the member depth in hundredths of an inch, the letter "s" representing a stud or joist member, the second number representing the flange width in hundredths of an inch and the letter "t" shall be a number representing the minimum base metal thickness in mils.
Load-bearing, cold-formed steel framing members shall have a legible label, stencil, stamp or embossment with the following information as a minimum:
- Manufacturer's identification.
- Minimum base steel thickness in inches (mm).
- Minimum coating designation.
- Minimum yield strength, in kips per square inch (ksi) (MPa).
Web holes in roof framing members shall comply with all of the following conditions:
- Holes shall conform to Figure R804.2.6.1.
- Holes shall be permitted only along the centerline of the web of the framing member.
- Center-to-center spacing of holes shall be not less than 24 inches (610 mm).
- The web hole width shall be not greater than one-half the member depth, or 21/2 inches (64 mm).
- Holes shall have a web hole length not exceeding 41/2 inches (114 mm).
- The minimum distance between the edge of the bearing surface and the edge of the web hole shall be not less than 10 inches (254 mm).
Framing members with web holes not conforming to Items 1 though 6 shall be reinforced in accordance with Section R804.2.6.2, patched in accordance with Section R804.2.6.3 or designed in accordance with accepted engineering practices.
Patching of web holes in roof framing members not conforming to the requirements in Section R804.2.6.1 shall be permitted in accordance with either of the following methods:
- 1.1. The depth of the hole, measured across the web, exceeds 70 percent of the flat width of the web.
- 1.2. The length of the hole measured along the web, exceeds 10 inches (254 mm) or the depth of the web, whichever is greater.
- Web holes not exceeding the dimensional requirements in Section R804.2.6.3, Item 1, shall be patched with a solid steel plate, stud section or track section in accordance with Figure R804.2.6.3. The steel patch shall, as a minimum, be the same thickness as the receiving member and shall extend not less than 1 inch (25 mm) beyond all edges of the hole. The steel patch shall be fastened to the web of the receiving member with No. 8 screws spaced not greater than 1 inch (25 mm) center-to-center along the edges of the patch with minimum edge distance of 1/2 inch (12.7 mm).
|DESCRIPTION OF BUILDING ELEMENTS||NUMBER AND SIZE OF FASTENERSa||SPACING OF FASTENERS|
|Roof sheathing (oriented strand board or plywood) |
|No. 8 screws||6" o.c. on edges and 12" |
o.c. at interior supports. 6"o.c. at gable end truss
|Gable end truss to endwall top track||No. 10 screws||12" o.c.|
|Rafter to ceiling joist||Minimum No. 10 screws, in accordance with||Evenly spaced, not less |
than 1/2" from all edges.
|Ceiling joist or |
roof truss to top
track of bearingwallb
|Ceiling Joist |
|Roof Span (ft)||Ultimate Design Wind Speed |
(mph) and Exposure Category
|Each ceiling joist |
or roof truss
|<139 B |
|126 C||<139 C|
- Screws are a minimum No. 10 unless noted otherwise.
- Indicated number of screws shall be applied through the flanges of the truss or ceiling joist or through each leg of a 54 mil clip angle. See Section R804.3.8 for additional requirements to resist uplift forces.