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Wind Loads

The Wind Load module works through ASCE 7 Chapters 26, 27, 28, and 30. General Requirements sets the site and building parameters the wind calculations share. MWFRS Directional calculates the design pressures on the main wind force resisting system by the Chapter 27 directional procedure, for any number of building regions. MWFRS Envelope applies the Chapter 28 procedure for low-rise buildings. Components & Cladding calculates the Chapter 30 zone pressures for walls, roofs, and parapets against effective wind area.

Features in Prose

  • Basic wind speed, exposure, the topographic factor, the ground elevation factor (ASCE 7-16 and 7-22), and the gust effect factor, entered once per structure
  • Exposure by direction when the terrain differs around the building
  • Enclosure classification with the internal pressure coefficients that follow from it
  • MWFRS directional procedure for buildings of all heights, with velocity pressures at every level and parapet, wall pressures for both internal pressure cases, roof pressures, and the minimum load case
  • Components and cladding zones for walls of buildings with h of 60 ft or less and h over 60 ft, roofs, and parapets, with pressures tabulated against effective wind area and the zone figures
  • A summary and report with the equation, figure, and table reference for every value

Editions

This page shows the ASCE 7-22 module, used by IBC 2024 projects. Projects on ASCE 7-10 or 7-16 show the inputs and figures those editions use. Each wind page has a Code Reference table with the section, figure, and equation numbers for each edition.

Tornado loads

ASCE 7-22 Chapter 32 adds tornado loads for Risk Category III and IV buildings in tornado-prone regions. The Wind Load module does not calculate them; check Chapter 32 separately where it applies.

Adding the Module

  1. Click the three-dot menu (⋮) next to the structure name in the sidebar
  2. Select Wind Load

A new module holds the General Requirements section only. The + button beside the section tabs adds MWFRS Directional, MWFRS Envelope (the Chapter 28 procedure for low-rise buildings), and Components & Cladding sections as you need them. Each added section gets its own tab, with a close mark that removes the section again.

Typical Workflow

  1. Set the basic wind speed, exposure, and the site factors in General Requirements
  2. Choose the enclosure classification
  3. Add an MWFRS Directional section, describe the building region, and read the wall, roof, and parapet pressures. See MWFRS Directional
  4. Add a Components & Cladding section and one region per element type. See Components & Cladding
  5. Export the report

PDF Export

  1. Click the Export PDF tab above the summary
  2. Review the report in the viewer
  3. Save the PDF from the viewer toolbar. In a narrow pane the Save button sits in the >> menu at the right end of the toolbar

The report carries every section: the general requirements, each MWFRS region with its pressure tables for both wind directions, and each components and cladding region with its zone tables and figures. The same pages appear in the project report.

Deleting the Module

  1. Hover the Wind Load entry under the structure in the sidebar and click its three-dot menu (⋮)
  2. Select Delete Module
  3. Confirm with Delete Wind Load

Code References

Topic ASCE 7-10 ASCE 7-16 ASCE 7-22
General requirements Chapter 26 Chapter 26 Chapter 26
MWFRS, directional procedure Chapter 27 Chapter 27 Chapter 27
MWFRS, envelope procedure Chapter 28 Chapter 28 Chapter 28
Components and cladding Chapter 30 Chapter 30 Chapter 30
Basic wind speed maps Figures 26.5-1A through 26.5-1C Figures 26.5-1A through 26.5-1D, and 26.5-2A through 26.5-2D for Hawaii Figures 26.5-1A through 26.5-1D, or the ASCE Wind Design Geodatabase
C&C external pressure coefficients Figures 30.4-1 through 30.4-7, and Figure 30.6-1 for h over 60 ft Figures 30.3-1 through 30.3-7, and Figure 30.5-1 for h over 60 ft Figures 30.3-1 through 30.3-8, and Figure 30.4-1 for h over 60 ft
Tornado loads None None Chapter 32, not calculated by Prose

Best Practices

  • Take the basic wind speed from the ASCE Hazard Tool for the project coordinates and the structure's risk category, and check it against the local building official's requirements
  • Use the more severe exposure where the terrain is in doubt, and set exposure by direction only when you have the terrain mapped
  • Decide the enclosure classification with the architect's opening schedule; a partially enclosed building raises the internal pressure coefficient GCpi from 0.18 to 0.55, about three times as much
  • Run both MWFRS and components and cladding; the corner and edge zones usually govern the cladding and its connections