Calculate Wind Loads: Components and Cladding (ASCE 7-22)

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Background

The Calcs.com Wind Load Calculator for Components and Cladding (C&C) provides a streamlined and accurate solution for calculating wind pressures in accordance with ASCE 7-22 Chapter 30. This calculator helps structural engineers quickly determine design wind pressures acting on specific building elements (such as purlins, girts, studs, and roof decking) and cladding, taking into account a wide range of building configurations, exposure conditions, and the new tornado load requirements introduced in ASCE 7-22. The calculator determines the required corner, edge, and field zones, wind pressure coefficients, and resulting design pressures, providing a comprehensive analysis for various design scenarios including Enclosed, Partially Enclosed, Partially Open, and Open buildings.

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Project Defaults

You can select whether the calculator will use the project defaults, where you can set the building code used for your project, as well as wind, snow, seismic, and general criteria. In particular, if you provide the project address in the Project Details as well as the Risk Category and Exposure Category, the basic wind speed and ground elevation will be automatically determined and used in your wind calculator. If you select to Override Project Defaults, you must manually input the following:

• Basic Wind Speed (V)
• Exposure Category (B, C, or D)
• Building Risk Category (I, II, III, or IV)
• Tornado-Prone Region status
• Tornado Speed (V_T) (if applicable)

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Key Properties

Under the key properties section, you can select Type of Calculation. For this article, we focus on Components and Cladding.

• Effective Roof Member Wind Area and Effective Wall Member Wind Area: tributary area of the member being designed (for example, a single roof truss or wall stud). These values set external pressure coefficients ($GC_p$) when Individual Effective Area per Wind Zone is No.
• Individual Effective Area per Wind Zone: set to Yes to define different effective areas in the Individual Effective Area table for each zone. Parapet inputs are hidden when this is Yes.

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Building Properties

This input allows you to define the geometry and enclosure classification of the structure.

• Roof Type: Supported roof types include Flat, Gable, Hip, and Monoslope.
  • Depending on the selection, you will define properties such as Roof Pitch, Roof Top Height ($h_t$), and Eave Height ($h_e$).
• Dimensions: Define the Building Width ($w$) and Length ($l$).
• Enclosure Type:
  • Enclosed: A structure with controlled openings (e.g., typical office buildings).
  • Partially Enclosed: A structure with large openings on one wall causing internal pressure buildup (e.g., a warehouse with a large open door during a storm).
  • Partially Open: A structure with significant openings on multiple walls.
  • Open: A structure with no walls, where wind flows freely over and under the roof (e.g., carports, canopies, agricultural sheds, and covered pavilions). For Open enclosures, the calculator uses free-roof net pressure coefficients ($C_N$) per Cl. 30.5, tabulated across interior, edge, and corner wind zones with three effective-wind-area bands per zone. Per Note 3 on the governing figures, interpolation is permitted only on roof angle ($\theta$), never on effective wind area. A minimum net design pressure of 16 psf is enforced per Cl. 30.2.2. Open enclosure support is currently limited to monoslope and gable roof shapes, with a single effective wind area applied uniformly across all zones.
• Large-Volume, Unpartitioned Building? (appears when Enclosure Type is Partially Enclosed): set to Yes for a single, unpartitioned large-volume building such as an arena, aircraft hangar, or open-interior warehouse. This exposes Unpartitioned Internal Volume ($V_i$) and Total Area of Envelope Openings ($A_{og}$), and applies the Internal Pressure Reduction Factor $R_i$ per Eq. 26.13-1 to $GC_{pi}$. Defaults to no reduction ($R_i = 1.0$).

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Terrain Properties

The calculator can automatically determine the Ground Elevation Above Sea Level if a project address is provided, calculating the Ground Elevation Factor ($K_e$) per ASCE 7-22 Section 26.9. Alternatively, a custom elevation can be entered. Topographic Effects: If the site is located on a hill, ridge, or escarpment, you can toggle Hill or Escarpment Present? to “Yes”. You must then select the Hill Shape (2D Ridge, 2D Escarpment, or 3D Axisymmetrical Hill) and provide:

• H: Height of feature relative to upwind terrain.
• L_h: Distance upwind of crest to mid-height of feature.
• x: Distance from crest to building site.

These inputs calculate the Topographic Factor ($K_{zt}$) per ASCE 7-22 Section 26.8.

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Tornado Load Parameters (ASCE 7-22 Chapter 32)

A significant addition to ASCE 7-22 is the requirement to check for Tornado Loads (Chapter 32). The calculator automatically performs the applicability check based on:

1. Risk Category: Generally applies to Risk Category III and IV structures (and some others depending on parameters).
2. Tornado-Prone Region: Whether the site is mapped in the tornado-prone region (Fig 32.1-1).
3. Tornado Speed: Compares the effective Tornado Speed ($V_T$) against the Basic Wind Speed ($V$).

If Tornado Loads Required calculates to “Yes”, the calculator will generate a specific Design Tornado Pressures table alongside standard wind pressures.

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Calculations and Results

Once all properties are defined, the calculator determines the following parameters per ASCE 7-22:

• Velocity Pressure ($q_h$): based on wind speed, exposure, ground elevation factor ($K_e$), and topography ($K_{zt}$).
• Internal Pressure Coefficient ($GC_{pi}$): based on enclosure type. For Partially Enclosed buildings, the Internal Pressure Reduction Factor $R_i$ (Eq. 26.13-1) can be applied when the building is a single, unpartitioned large volume.
• External Pressure Coefficients ($GC_p$): based on effective wind area and zone (corner, edge, field).

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Method & scope

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What it calculates

US structural engineers calculating wind loads to ASCE 7-22 for Components and Cladding and MWFRS. Covers velocity pressure, pressure coefficients, and design pressures for low-rise buildings, with override options for exposure, topography, and directionality. Calculate wind pressures for both C&C and MWFRS in one template, aligned to ASCE 7-22 and IBC 2024.

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Calculation method

The Wind Loads (ASCE 7-22) calculator determines design wind pressures for low-rise buildings in the US per ASCE 7-22. It covers three distinct 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 7-22 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 7-22 Cl. 26.8, or entered as 1.0 for flat terrain
• Ground elevation factor (K_e), based on elevation above sea level per ASCE 7-22

Velocity pressure

The design velocity pressure at height z is: q_z = 0.00256 × K_z × K_zt × K_d × K_e × V² (lb/ft², V in mph) At mean roof height h, this becomes q_h, which is the reference pressure for C&C and MWFRS envelope calculations.

C&C pressures (ASCE 7-22 Ch. 30)

External pressure coefficients (GCp) are looked up from ASCE 7-22 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.

Tornado loads (ASCE 7-22 Ch. 32)

If tornado speed (V_T) is specified, tornado pressures are calculated and reported separately alongside wind pressures.

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 7-22 clause.

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How to use it

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Available presets

Each preset opens the calculator with a typical setup already entered.

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Common questions

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Next steps