What it calculates
Calculate MWFRS and C&C wind pressures to ASCE 7-16 for low-rise buildings. Velocity pressure, pressure coefficients, and design pressures are shown alongside code references. Use for projects under IBC 2021 or when the AHJ specifies ASCE 7-16.
Who uses this calculator
US structural engineers calculating wind loads to ASCE 7-16 for projects under IBC 2021. Covers velocity pressure, pressure coefficients, and design pressures for both MWFRS and C&C in a single calculation. For IBC 2024 projects, use the ASCE 7-22 version instead.
Calculate wind pressures for both C&C and MWFRS in one template, aligned to ASCE 7-16 and IBC 2021.
How it calculates
The Wind Loads (ASCE 7-16) calculator determines design wind pressures for low-rise buildings per ASCE 7-16. It covers three procedures in a single template: Components and Cladding (C&C) per Chapter 30 Part 1 (Cl. 30.3), the MWFRS Envelope Procedure per Chapter 28, and the MWFRS Directional Procedure per Chapter 27.
Site and building inputs
Key inputs are:
- Basic wind speed (V) - from the ASCE 7-16 Figure 26.5-1 maps, or entered manually
- Exposure category - B, C, or D, which sets the velocity pressure exposure coefficient K_z
- Building dimensions - roof mean height (h), least horizontal dimension (B_min), and roof pitch (alpha)
- Enclosure classification - enclosed, partially enclosed, or open, which drives internal pressure coefficients (GCpi)
- Topographic factor (K_zt) - computed from hill height, half-length, and site distance per ASCE 7-16 Cl. 26.8, or entered as 1.0 for flat terrain
Velocity pressure
The design velocity pressure at height z is:
q_z = 0.00256 × K_z × K_zt × K_d × V² (lb/ft², V in mph)
At mean roof height h, this becomes q_h, the reference pressure for C&C and MWFRS envelope calculations.
C&C pressures (ASCE 7-16 Ch. 30)
External pressure coefficients (GCp) are looked up from ASCE 7-16 figures as a function of effective wind area and roof zone (zones 1, 2, 3 for roofs; zones 4 and 5 for walls). Net design pressure combines external and internal coefficients:
p = q_h × [(GCp) - (GCpi)]
Zone widths a, 0.6h, and 0.2h are calculated automatically from building dimensions. Separate pressures are reported for roof and wall members for the effective areas entered.
MWFRS pressures
For the Envelope Procedure (Chapter 28), pseudo-lateral pressures on windward and leeward walls and roof zones are determined using simplified load cases A and B for both wind directions. For the Directional Procedure (Chapter 27), wall and roof pressure coefficients (Cp) are used with the velocity pressure at each height, and load cases 1 and 2 are applied. Overhang bottom-surface pressure is also calculated for both procedures.
Assumptions and limitations
The calculator assumes no parapets (unless the parapet option is enabled), flat/gable/hip/monoslope roof geometry, and Cl. 26.2 low-rise building classification. The b-note reduction for pressure coefficients in the Directional Procedure is not applied. Results are tabulated by zone and load case, with each pressure linked to its governing ASCE 7-16 clause.
