9.23.13.7.Additional System Considerations

(1) Except as provided in Sentences (2) and (3), one exterior wall of the uppermost storey in each orthogonal direction may be set back from the exterior wall of the storey below, provided the adjacent interior braced wall band of the storey below the setback (a) is spaced not more than 10.6 m from the exterior wall of the storey below the setback wall, (b) consists of braced wall panels that are constructed of a wood-based material in conformance with Sentence 9.23.13.6.(2), (c) extends to the foundation, and (d) is not taken into consideration when providing braced wall panels constructed of a wood-based material at spacing intervals of not more than 15 m as per Sentence 9.23.13.6.(6). (2) Where the exterior wall of the uppermost storey is set back from the exterior wall of the storey below, the roof and floor space supporting the setback wall shall be sheathed with a wood-based material between the exterior wall of the storey below the setback and the adjacent interior braced wall bands of the storey below the setback. (3) Where the exterior wall of the uppermost storey is set back from the exterior wall of the storey below, the exterior walls perpendicular to the setback wall shall (a) have their top plate connected with nails that are spaced at no greater than half the spacing required in Table 9.23.3.4., and (b) have their top plate splices fastened with twice the number of nails specified in Sentences 9.23.11.4.(4) and (5). (4) The maximum distance between adjacent required braced wall panels in a braced wall band, measured from the edge of the panels, may be increased to 7.3 m provided that, throughout the height of the building, the length of any braced wall panel within the braced wall band is not less than 1.2 m. (5) The maximum spacing between the centre lines of required braced wall bands given in Table 9.23.13.5. may be increased from 7.6 m to no more than 10.6 m, provided that the interior braced wall band whose spacing is being increased is replaced with an interior braced wall band that (a) consists of braced wall panels that are constructed of a wood-based material in conformance with Sentence 9.23.13.6.(2), (b) extends to the foundation, and (c) is not taken into consideration when providing braced wall panels constructed of a wood-based material at spacing intervals no greater than 15 m as per Sentence 9.23.13.6.(6). (6) For each orthogonal direction of the building, the length of required braced wall panels of one exterior wall given in Table 9.23.13.5. may be reduced from 40% to no less than 25% of the length of the braced wall band, provided an additional parallel and adjacent interior braced wall band is constructed that (a) is spaced not more than 10.6 m from the exterior wall, (b) consists of braced wall panels that are constructed of a wood-based material in conformance with Sentence 9.23.13.6.(2) and whose lengths sum to no less than 25% of the length of the braced wall band, (c) extends to the foundation, and (d) is not taken into consideration when providing braced wall panels constructed of a wood-based material at spacing intervals no greater than 15 m as per Sentence 9.23.13.6.(6). (7) Where the length of required braced wall panels of an exterior wall is reduced as described in Sentence (6), the ratio of the length of braced wall panels in the respective upper braced wall bands to the length of braced wall panels in the reduced exterior braced wall band shall not exceed 2.