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# Wind Loads (ASCE 7-16 and ASCE 7-22) - MWFRS Directional Procedure
> How to use the MWFRS Directional Procedure in the Calcs.com Wind Loads calculators per ASCE 7 Chapter 27.
Both [Wind Loads (ASCE 7-16)](/calculations/us/wind_loads__asce_7_16____mwfrs_overview) and [Wind Loads (ASCE 7-22)](/calculations/us/wind_loads_asce_7_22_components_and_cladding_overview) include **MWFRS (Directional Procedure)** per ASCE 7 Chapter 27. This mode calculates direction-dependent wind pressures on walls and roofs using building geometry, wind direction, and external pressure coefficients from Fig. 27.3-1.
**Create a wind load sheet with the Directional Procedure preset:**
* [Wind Loads (ASCE 7-16)](https://calcs.com/new/sheet/loadsWindCnCASCE7-16?presetCode=MWFRS+%28Directional+Procedure%29)
* [Wind Loads (ASCE 7-22)](https://calcs.com/new/sheet/loadsWindCnCASCE7-22?presetCode=MWFRS+%28Directional+Procedure%29)
## Background
The Directional Procedure evaluates wind pressures for a single wind direction at a time. You choose whether wind acts normal to the long building axis or normal to the short axis, and the calculator determines windward, leeward, sidewall, and roof pressures from interpolated $C_p$ values in Fig. 27.3-1.
This differs from the **MWFRS (Envelope Procedure)** (Chapter 28), which envelopes multiple load cases without selecting a primary wind direction. Use the Directional Procedure when you need explicit direction-specific MWFRS pressures tied to $L/B$, $h/L$, and roof angle.
## Key properties
Under **Key Properties**, set **Type of Calculation** to **MWFRS (Directional Procedure)**.
Project defaults for **Basic Wind Speed**, **Exposure Category**, and **Risk Category** work the same as other wind load modes. Override them at the top of the sheet if needed.
## Wind Load Parameters
When **MWFRS (Directional Procedure)** is selected, **Gust Effect Factor** ($G$) appears in the **Wind Load Parameters** section below **Key Properties**. It defaults to 0.85 for rigid buildings (natural frequency greater than 1 Hz) per Cl. 26.11.1.
## Building properties
Define roof geometry, dimensions, and enclosure classification as usual. For the Directional Procedure, **Roof Type** supports **Flat**, **Gable**, **Hip**, and **Monoslope** (the Envelope Procedure is limited to flat and gable roofs).
Directional-specific inputs and computed values include:
* **Wind Direction**: choose **N-S Direction (Normal to Ridge)** or **E-W Direction (Parallel to Ridge)**. This sets which building dimension is treated as $L$ (parallel to wind) and $B$ (normal to wind).
* **Horizontal Dimension Parallel to Wind Direction** ($L$) and **Horizontal Dimension Normal to Wind Direction** ($B$): derived from **Width (Perpendicular to Ridge)** and **Length (Parallel to Ridge)** based on the selected wind direction.
* **L/B Ratio (for Directional Procedure)**: used for the leeward wall $C_p$.
* **h/L Ratio (for Directional Procedure)**: mean roof height divided by $L$; used for roof $C_p$ interpolation.
* **Roof Angle in Wind Direction** ($\theta_{dir}$): equals the roof slope for most cases, or 0° when wind is parallel to the ridge (E-W on a gable roof).
A diagram under **Wind Direction** in the summary shows windward and leeward surfaces for the selected direction.
Optional **Include Roof Overhangs?** = **Yes** adds **Roof Overhang External Pressure Coefficient** and **Roof Overhangs Bottom Surface Pressure** for the directional procedure (Cl. 27.3.3).
## Intermediate calculations
The calculator follows the ASCE 7 Chapter 27 workflow:
1. **Velocity Pressure** ($q_h$) at mean roof height, including exposure, topographic, and ground elevation factors where applicable.
2. **Wind Directionality Factor** ($K_d$) per Table 26.6-1 (included in ASCE 7-22 directional pressure equations; computed on ASCE 7-16 sheets but not multiplied into the directional summary pressures).
3. **Internal Pressure Coefficient** ($GC_{pi}$) from enclosure type.
4. **Roof External Pressure Coefficients** table: $C_p$ for windward wall, leeward wall, sidewall, and roof surfaces from Fig. 27.3-1, with linear interpolation for $L/B$, $h/L$, and $\theta_{dir}$ where permitted by the figure notes.
**Calculator assumption**
The reduction in roof pressure coefficients per footnote **b** in Fig. 27.3-1 (linear reduction with tributary area) is **not** applied in the current template.
For sloped roofs ($\theta_{dir} \geq 10°$), the roof table reports separate windward minimum/maximum and leeward coefficients. For low-slope roofs ($\theta_{dir} < 10°$), roof zones are split by distance from the windward edge (0 to $h/2$, $h/2$ to $h$, $h$ to $2h$, and beyond $2h$), with separate minimum and maximum $C_p$ values where Fig. 27.3-1 requires both.
## Results
The summary includes:
* **Wind Pressures**: design pressures for each MWFRS surface, reported as **Wind Pressure (Positive Internal)** and **Wind Pressure (Negative Internal)** to cover both internal pressure cases.
* **Wind Pressures for Windward Wall**: height-varying pressures on the windward wall when velocity pressure varies with height (including topographic effects).
* **Note: Minimum design wind pressures (Directional)**: ASCE 7 requires minimum ultimate pressures of 16 psf on windward walls and 8 psf on leeward walls and roofs (Cl. 27.1.5). Compare calculated values against these minimums in your design.
Design pressure form:
* **ASCE 7-22:** $p = q_h K_d (G C_p \mp GC_{pi})$
* **ASCE 7-16:** $p = q_h (G C_p \mp GC_{pi})$ (the template applies $K_d = 0.85$ in other modes but omits it from the directional pressure equations shown in the summary)
Both editions report **Wind Pressure (Positive Internal)** and **Wind Pressure (Negative Internal)** columns to cover both internal pressure cases.
When **Include Parapets?** is enabled, see [Wind Load Parapets (ASCE 7-16 and ASCE 7-22)](/calculations/us/wind_loads_parapets_asce_7) for parapet pressure outputs.
**ASCE 7-22 tornado loads**
If **Tornado Loads Required** is **Yes**, the calculator notes that MWFRS (Directional Procedure) does not currently include tornado load calculations. Contact support if you need this functionality on a directional sheet.
## Related articles
* [Wind Loads (ASCE 7-16) - MWFRS Overview](/calculations/us/wind_loads__asce_7_16____mwfrs_overview) (Envelope Procedure)
* [Wind Loads (ASCE 7-22) - Components and Cladding Overview](/calculations/us/wind_loads_asce_7_22_components_and_cladding_overview)
* [Wind Load Parapets (ASCE 7-16 and ASCE 7-22)](/calculations/us/wind_loads_parapets_asce_7)