City of Bemidji Building Office City Hall 317 4th Street NW Bemidji, Minnesota 56601-3116 Phone 218-759-3573 Fax 218-759-3590 emi mn s Residential Header and Girder Spans Requirements 2015 MSBC Chapter 1309 Rev 170310 This handout is intended only as a guide and is based in part on the 2015 Minnesota State Building Code as adopted by the City of Bemidji as well as good building practice. While every attempt has been made to insure the correctness of this handout, no guarantees are made to its accuracy or completeness. Responsibility for compliance with applicable codes and ordinances falls on the owner or contractor. To obtain a copy of the 2015 Minnesota State Building Code, go to: http://www.dli.mn.gov/ccld/codes15.asp The following tables and diagrams are excerpts from 2015 MSBC 1309.R500 Floors and 2015 MSBC 1309.R600 Walls. These tables and diagrams are provided to help with the design and sizing of typical residential frame construction members. This is not an all-inclusive list and these sections of the Residential Building Code should be referenced for correct framing details. Please note specifically 1309.R610 Wall Bracing, provides the requirements for wall bracing that must be incorporated into all residential construction projects unless constructed under 1309.R612 Simplified Wall Bracing. R502.5 Allowable girder spans. The allowable spans of girders fabricated of dimension lumber shall not exceed the values set forth in Tables R502.5(1) and R502.5(2). TABLE R502.5(1) GIRDER SPANS a AND HEADER SPANS a FOR EXTERIOR BEARING WALLS ( spans for Douglas fir-larch, hem-fir, southern pine and spruce-pine-fir b and required number of jack studs) GIRDERS AND HEADERS SUPPORTING Roof and ceiling Roof, ceiling and one center-bearing floor GROUND SNOW LOAD (psf) e 30 50 70 SIZE Building width c (feet) 20 28 36 Span NJ d Span NJ d Span NJ d 2-2 4 2-10 1 2-6 1 2-3 1 2-2 6 4-2 1 3-8 2 3-3 2 2-2 8 5-4 2 4-7 2 4-1 2 2-2 10 6-6 2 5-7 2 5-0 2 2-2 12 7-6 2 6-6 2 5-10 3 3-2 8 6-8 1 5-9 2 5-2 2 3-2 10 8-2 2 7-0 2 6-4 2 3-2 12 9-5 2 8-2 2 7-4 2 4-2 8 7-8 1 6-8 1 5-11 2 4-2 10 9-5 2 8-2 2 7-3 2 4-2 12 10-11 2 9-5 2 8-5 2 2-2 4 2-7 1 2-3 1 2-0 1 2-2 6 3-9 2 3-3 2 2-11 2 2-2 8 4-9 2 4-2 2 3-9 2 2-2 10 5-9 2 5-1 2 4-7 3 2-2 12 6-8 2 5-10 3 5-3 3 3-2 8 5-11 2 5-2 2 4-8 2 3-2 10 7-3 2 6-4 2 5-8 2
3-2 12 8-5 2 7-4 2 6-7 2 4-2 8 6-10 1 6-0 2 5-5 2 4-2 10 8-4 2 7-4 2 6-7 2 4-2 12 9-8 2 8-6 2 7-7 2 2-2 4 2-5 1 2-1 1 1-10 1 2-2 6 3-6 2 3-1 2 2-9 2 2-2 8 4-6 2 3-11 2 3-6 2 2-2 10 5-6 2 4-9 2 4-3 3 2-2 12 6-4 2 5-6 3 5-0 3 Roof, ceiling and one clear span floor 3-2 8 5-7 2 4-11 2 4-5 2 3-2 10 6-10 2 6-0 2 5-4 2 3-2 12 7-11 2 6-11 2 6-3 2 4-2 8 6-6 1 5-8 2 5-1 2 4-2 10 7-11 2 6-11 2 6-2 2 4-2 12 9-2 2 8-0 2 7-2 2 2-2 4 2-4 1 2-0 1 1-9 1 2-2 6 3-5 2 3-0 2 2-8 2 2-2 8 4-4 2 3-9 2 3-5 2 2-2 10 5-3 2 4-7 3 4-2 3 2-2 12 6-1 3 5-4 3 4-10 3 Roof, ceiling and two center-bearing floors 3-2 8 5-5 2 4-9 2 4-3 2 3-2 10 6-7 2 5-9 2 5-3 2 3-2 12 7-8 2 6-9 2 6-1 3 4-2 8 6-3 2 5-6 2 4-11 2 4-2 10 7-7 2 6-8 2 6-0 2 4-2 12 8-10 2 7-9 2 7-0 2 2-2 4 2-0 1 1-8 1 1-5 2 Roof, ceiling, and two clear span floors 2-2 6 2-11 2 2-7 2 2-3 2 2-2 8 3-9 2 3-3 2 2-11 3 GIRDERS AND HEADERS SUPPORTING Roof, ceiling, and two clear span floors GROUND SNOW LOAD (psf) e 30 50 70 SIZE Building width c (feet) 20 28 36 Span NJ d Span NJ d Span NJ d 2-2 10 4-7 3 4-0 3 3-6 3 2-2 12 5-4 3 4-7 3 4-1 4 3-2 8 4-8 2 4-1 2 3-8 2 3-2 10 5-9 2 4-11 2 4-5 3 3-2 12 6-8 2 5-9 3 5-2 3 4-2 8 5-5 2 4-8 2 4-2 2 4-2 10 6-7 2 5-9 2 5-1 2 4-2 12 7-8 2 6-8 2 5-11 3 For SI: 1 inch = 25.4 mm, 1 pound per square foot = 0.0479 kpa. a. Spans are given in feet and inches. b. Tabulated values assume #2 grade lumber. c. Building width is measured perpendicular to the ridge. For widths between those shown, spans are permitted to be interpolated. Page 2 of 8
d. NJ - Number of jack studs required to support each end. Where the number of required jack studs equals one, the header is permitted to be supported by an approved framing anchor attached to the full-height wall stud and to the header. e. Use 30 psf ground snow load for cases in which ground snow load is less than 30 psf and the roof live load is equal to or less than 20 psf. TABLE R502.5(2) GIRDER SPANS a AND HEADER SPANS a FOR INTERIOR BEARING WALLS ( spans for Douglas fir-larch, hem-fir, southern pine and spruce-pine-fir b and required number of jack studs) HEADERS AND GIRDERS SUPPORTING One floor only Two floors SIZE BUILDING Width c (feet) 20 28 36 Span NJ d Span NJ d Span NJ d 2-2 4 3-1 1 2-8 1 2-5 1 2-2 6 4-6 1 3-11 1 3-6 1 2-2 8 5-9 1 5-0 2 4-5 2 2-2 10 7-0 2 6-1 2 5-5 2 2-2 12 8-1 2 7-0 2 6-3 2 3-2 8 7-2 1 6-3 1 5-7 2 3-2 10 8-9 1 7-7 2 6-9 2 3-2 12 10-2 2 8-10 2 7-10 2 4-2 8 9-0 1 7-8 1 6-9 1 4-2 10 10-1 1 8-9 1 7-10 2 4-2 12 11-9 1 10-2 2 9-1 2 2-2 4 2-2 1 1-10 1 1-7 1 2-2 6 3-2 2 2-9 2 2-5 2 2-2 8 4-1 2 3-6 2 3-2 2 2-2 10 4-11 2 4-3 2 3-10 3 2-2 12 5-9 2 5-0 3 4-5 3 3-2 8 5-1 2 4-5 2 3-11 2 3-2 10 6-2 2 5-4 2 4-10 2 3-2 12 7-2 2 6-3 2 5-7 3 4-2 8 6-1 1 5-3 2 4-8 2 4-2 10 7-2 2 6-2 2 5-6 2 4-2 12 8-4 2 7-2 2 6-5 2 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm. a. Spans are given in feet and inches. b. Tabulated values assume #2 grade lumber. c. Building width is measured perpendicular to the ridge. For widths between those shown, spans are permitted to be interpolated. d. NJ - Number of jack studs required to support each end. Where the number of required jack studs equals one, the header is permitted to be supported by an approved framing anchor attached to the full-height wall stud and to the header. Page 3 of 8
R502.8 Cutting, drilling and notching. Structural floor members shall not be cut, bored or notched in excess of the limitations specified in this section. See Figure R502.8. For SI: 1 inch = 25.4 mm. FIGURE R502.8 CUTTING, NOTCHING AND DRILLING Page 4 of 8
R501.3 Fire protection of floors. Floor assemblies, not required elsewhere in this code to be fire-resistance rated, shall be provided with a 1 / 2-inch (12.7 mm) gypsum wallboard membrane, 5 / 8-inch (16 mm) wood structural panel membrane, or equivalent on the underside of the floor framing member. Exceptions: 1. Floor assemblies located directly over a space protected by an automatic sprinkler system in accordance with Section P2904, NFPA13D, or other approved equivalent sprinkler system. 2. Floor assemblies located directly over a crawl space not intended for storage or fuel-fired appliances. 3. Portions of floor assemblies can be unprotected when complying with the following: 3.1. The aggregate area of the unprotected portions shall not exceed 80 square feet per story. 3.2. Fire blocking in accordance with Section R302.11.1 shall be installed along the perimeter of the unprotected portion to separate the unprotected portion from the remainder of the floor assembly. 4. Wood floor assemblies using dimension lumber or structural composite lumber equal to or greater than 2-inch by 10-inch (50.8 mm by 254 mm) nominal dimension, or other approved floor assemblies demonstrating equivalent fire performance. R602.3.1 Stud size, height and spacing. The size, height and spacing of studs shall be in accordance with Table R602.3.(5). Exceptions: 1. Utility grade studs shall not be spaced more than 16 inches (406 mm) on center, shall not support more than a roof and ceiling, and shall not exceed 8 feet (2438 mm) in height for exterior walls and load-bearing walls or 10 feet (3048 mm) for interior nonload-bearing walls. 2. Studs more than 10 feet (3048 mm) in height which are in accordance with Table R602.3.1. TABLE R602.3(5) SIZE, HEIGHT AND SPACING OF WOOD STUDS a STUD SIZE Laterally unsupported stud height a (feet) spacing when supporting a roof-ceiling assembly or a habitable attic assembly, only BEARING WALLS spacing when supporting one floor, plus a roofceiling assembly or a habitable attic assembly spacing when supporting two floors, plus a roofceiling assembly or a habitable attic assembly spacing when supporting one floor height a NONBEARING WALLS Laterally unsupported stud height a spacing (feet) 2 3 b 10 16 2 4 10 24 c 16 c 24 14 24 Page 5 of 8
3 4 10 24 24 16 24 14 24 2 5 10 24 24 24 16 24 2 6 10 24 24 16 24 20 24 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 square foot = 0.093 m 2. a. Listed heights are distances between points of lateral support placed perpendicular to the plane of the wall. Increases in unsupported height are permitted where justified by analysis. b. Shall not be used in exterior walls. c. A habitable attic assembly supported by 2 4 studs is limited to a roof span of 32 feet. Where the roof span exceeds 32 feet, the wall studs shall be increased to 2 6 or the studs shall be designed in accordance with accepted engineering practice. For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm. Page 6 of 8
FIGURE R602.3(1) TYPICAL WALL, FLOOR AND ROOF FRAMING For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm. FIGURE R602.3(2) FRAMING DETAILS Page 7 of 8
R602.10 Wall bracing. Buildings shall be braced in accordance with this section or, when applicable, Section R602.12. Where a building, or portion thereof, does not comply with one or more of the bracing requirements in this section, those portions shall be designed and constructed in accordance with Section R301.1. SECTION R301 DESIGN CRITERIA R301.1 Application. Buildings and structures, and all parts thereof, shall be constructed to safely support all loads, including dead loads, live loads, roof loads, flood loads, snow loads, wind loads and seismic loads as prescribed by this code. The construction of buildings and structures in accordance with the provisions of this code shall result in a system that provides a complete load path that meets all requirements for the transfer of all loads from their point of origin through the load-resisting elements to the foundation. Buildings and structures constructed as prescribed by this code are deemed to comply with the requirements of this section. R301.1.1 Alternative provisions. As an alternative to the requirements in Section R301.1 the following standards are permitted subject to the limitations of this code and the limitations therein. Where engineered design is used in conjunction with these standards, the design shall comply with the International Building Code. 1. AF&PA Wood Frame Construction Manual (WFCM). 2. AISI Standard for Cold-Formed Steel Framing Prescriptive Method for One- and Two-Family Dwellings (AISI S230). 3. ICC Standard on the Design and Construction of Log Structures (ICC 400). R301.1.2 Construction systems. The requirements of this code are based on platform and balloon-frame construction for light-frame buildings. The requirements for concrete and masonry buildings are based on a balloon framing system. Other framing systems must have equivalent detailing to ensure force transfer, continuity and compatible deformations. R301.1.3 Engineered design. When a building of otherwise conventional construction contains structural elements exceeding the limits of Section R301 or otherwise not conforming to this code, these elements shall be designed in accordance with accepted engineering practice. The extent of such design need only demonstrate compliance of nonconventional elements with other applicable provisions and shall be compatible with the performance of the conventional framed system. Engineered design in accordance with the International Building Code is permitted for all buildings and structures, and parts thereof, included in the scope of this code. Page 8 of 8