Wind Load Calculator

This calculator works through the ASCE/SEI 7-22 simplified wind pressure procedure for a rectangular, enclosed or partially-enclosed building. It starts with velocity pressure, qz = 0.613 × Kz × Kzt × Kd × V² — the equation ASCE 7 Chapter 26 defines for converting a basic wind speed into a design pressure — using a fixed directionality factor Kd of 0.85 and a topographic factor Kzt of 1.0 (flat terrain, no speed-up). The exposure coefficient Kz is derived from a simplified power-law formula whose exponent and gradient height shift by exposure category — steeper for Exposure D's flat, unobstructed terrain than for Exposure B's urban roughness — evaluated at your building's mean roof height (floored at 4.5 m).

From velocity pressure, the calculator applies a fixed 0.85 gust factor for a rigid structure along with representative windward (+0.8) and leeward (−0.5) external pressure coefficients, then adds or subtracts an internal pressure coefficient (GCpi) that swings between ±0.18 for enclosed buildings and a much larger ±0.55 for partially enclosed ones — reflecting how a breached envelope amplifies internal suction and pressure. Combining the windward and leeward net pressures and multiplying by the windward wall area (width × height) gives a total wind force, reported again as base shear. Because the pressure coefficients and gust factor are fixed representative values rather than calculated from your building's specific aspect ratio and roof geometry, this is a preliminary estimate suited to early design — a full ASCE 7 Chapter 27/28 analysis is still needed for final cladding and lateral system design.