§ 27-622 Empirical provisions in lieu of design.
AC § 27-622
The provisions of this section may be used in lieu of structural analysis only for those buildings in occupancy group J-3 where the specific occupancies correspond to a live load requirement of forty psf, or less, and to constructions wherein the supporting framing consists of multiple, closely spaced members, such as joists, studs, platform or balloon frames. All wood structural members in other classes of construction shall be proportioned on the basis of the analysis of stresses. All requirements established in this section may be reduced when an analysis of stresses, executed in accordance with reference standard RS 10-8, indicates such reduction is feasible. Sizes of wood members stated in this section are nominal sizes.
(a)Stud walls and partitions.
(1)Studs shall be of equivalent or better grade than the minimum grades for the various species as established in reference standard RS 10-13.
(2)Corner posts shall be 3-stud members or members of equivalent strength.
(3)Load bearing studs shall be set with the larger cross section dimension perpendicular to the wall or partition. Studs in exterior walls of one story buildings of construction class II-D and II-E shall be at least two inches by three inches spaced not more than sixteen inches on center, or where studs are two inches by four inches, spaced not more than twenty-four inches on center. Studs for other classes of construction shall be at least two inches by four inches spaced not more than sixteen inches on center.
(4)Stud walls resting on concrete or masonry shall have sills at least two inches in nominal thickness. Where such sills bear on concrete, they shall be fastened with minimum one-half inch bolts embedded at least six inches. Each sill piece shall have at least two anchor bolts, with one bolt located at least one inch from each end of the plate, and with intermediate spacing not more than eight feet. Where such sills bear on masonry, they shall be anchored in accordance with the applicable provisions of reference standard RS 10-1.
(5)Stud partitions that rest directly over each other and are not parallel to floor joists or beams may extend down between the joists and rest on the top plate of the partition, partition girder, or foundation below, or may be constructed on sill plates running on top of the beams or joists.
(6)All load bearing stud partitions shall be supported on walls, other partitions, double joists or beams, solid bridging, or on beams at least as wide as the studs. Joists supporting a partition parallel to the joists wherein the joists are spaced apart to permit the passage of piping or duct work shall be provided with solid blocking at intervals of not more than sixteen inches.
(7)Load bearing partitions perpendicular to joists shall not be offset from supporting girders, walls or partitions by more than the depth of the joists unless the joists are proportioned on the basis of analysis of stress.
(8)In interior walls and in bearing partitions, double studs shall be provided at the sides of openings that are greater than three feet six inches up to six feet in width, and triple-studs shall be provided at the sides of openings of greater width.
(9)Headers shall be provided over each opening in exterior walls and bearing partitions. Where the opening does not exceed three feet, each end of the header shall be supported on a stud or framing anchor. Where the opening exceeds three feet in width each end of the header shall be supported on one stud and where the opening exceeds six feet each end shall be supported on two studs.
(10)All studs in exterior walls and in bearing partitions shall be capped with double top plates installed to provide overlapping at corners and at intersections with other walls and bearing partitions. End joists in double top plates shall be offset at least twenty-four inches. In lieu of double top plates, a continuous header of similar dimensions may be used. For platform frame construction, studs shall rest on a single bottom plate.
(b)Bracing of exterior walls. Exterior stud walls shall be braced by one inch by four inch continuous diagonal strips let into the face of the studs and into the top and bottom plates at each corner of the building. Bracing may also be provided by one of the following means: (1) Wood board sheathing of one inch nominal thickness, applied diagonally.
(c)Floor and roof framing.
(d)Nailing schedule. The size and number of nails for connections shall be in accordance with table 10-4.
