Velocity Pressure Exposure Coefficient Kz (ASCE 7 §26.10)

ASCE 7 §26.10.1 Kz = 2.01 (z/zg)^(2/alpha) for 15 ft <= z <= zg (held at the z = 15 ft value below), with Table 26.10-1 constants (B 7.0/1200 ft, C 9.5/900 ft, D 11.5/700 ft). It scales qz = 0.00256 Kz Kzt Kd Ke V^2, so it rises with height and a smoother exposure. At 30 ft it returns 0.70/0.98/1.16 (B/C/D) -- the hard-coded stub -- but a 50 ft eave in Exposure C is 1.09, about 11% more pressure. Use Kz at each height for the windward wall, Kh (at mean roof height) for leeward/side/roof and all C&C. The engineer of record governs.

Kz = 2.01 (z/zg)^(2/alpha) for 15 ft <= z <= zg; Kz = 2.01 (15/zg)^(2/alpha) for z < 15 ft. Table 26.10-1: B alpha 7.0 zg 1200, C 9.5/900, D 11.5/700.

The ASCE 7 §26.10.1 velocity pressure exposure coefficient Kz, with the Table 26.10-1 terrain exposure constants (alpha, zg), by name.

ASCE 7 is available through the ASCE Library at ascelibrary.org; the §26.10 exposure-coefficient equation and the Table 26.10-1 constants are public. The height z is the user's own building dimension.

Estimate. AHJ and licensed professional govern.

Field names used by the API: exposure, z_ft, kz

• Exposure coefficient Kz = 2.01 (z/zg)^(2/alpha), held at the z = 15 ft value below 15 ftASCE 7 §26.10.1 Eq. 26.10-1
• Exposure constants B alpha 7.0 zg 1200; C 9.5/900; D 11.5/700ASCE 7 Table 26.10-1
• Use Kz per height z for windward, Kh (mean roof height) for leeward/side/roof and all C&CASCE 7 Ch. 27/30