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Table 1. Maximum Horizontal Anchor Spacing Roof Slope Rafter Spacing 16” o.c.24” o.c.32” o.c. Photovoltaic Arrays (4 psf max) Flat to 6:12 0° to 26°5’-4”6’-0”5’-4” 7:12 to 12:12 27° to 45°1’-4”2’-0”2’-8” 13:12 to 24:12 46° to 63°1’-4”2’-0”2’-8” Solar Thermal Arrays (5 psf max) Flat to 6:12 0° to 26°4’-0”4’-0”5’-4” 7:12 to 12:12 27° to 45°1’-4”2’-0”2’-8” 13:12 to 24:12 46° to 63°Calc. Req’d Calc. Req’d Calc. Req’d Solar support component manufacturer’s guidelines may be relied upon to ensure the array above the roof is properly designed, but manufacturer’s guidelines typically do NOT check to ensure that the roof itself can support the concentrated loads from the solar array. Table 1 assumes that the roof complied with the building code in effect at the time of construction, and places limits on anchor horizontal spacing to ensure that a roof structure is not overloaded under either downward loads or wind uplift loads. Note 4 below lists the basic assumptions upon which this table is based. Table 1 Notes: 1. Anchors are also known as “stand-offs”, “feet”, “mounts” or “points of attachment”. Horizontal anchor spacing is also known as “cross-slope” or “east-west” anchor spacing (see Figure 2). 2. If anchors are staggered from row-to-row going up the roof, the anchor spacing may be twice that shown above, but no greater than 6’-0”. 3. For manufactured plated wood trusses at slopes of flat to 6:12, the horizontal anchor spacing shall not exceed 4’-0” and anchors in adjacent rows shall be staggered. 4. This table is based on the following assumptions: • The roof structure conformed to building code requirements at the time it was built. • The attached list of criteria are met. • Mean roof height is not greater than 40 feet. • Roof sheathing is at least 7/16” thick oriented strand board or plywood. 1x skip sheathing is acceptable. • If the dwelling is in Wind Exposure B (typical urban, suburban or wooded areas farther than 500 yards from large open fields), no more than one of the following conditions apply: – The dwelling is located in a special wind region with design wind speed between 115 and 130 mph per ASCE 7-10, or – The dwelling is located on the top half of a tall hill, provided average slope steeper is less than 15%. • If the dwelling is In Wind Exposure C (within 500 yards of large open fields or grasslands), all of the following conditions apply: – Design wind speed is 110 mph or less (not in a Special Wind Region), and – The dwelling is not located on the top half of a tall hill. • The solar array displaces roof live loads (temporary construction loads) that the roof was originally designed to carry. • The Structural Technical Appendix provides additional information about analysis assumptions. 1206 W 18th St 09/18/23