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How to Use the Mullion Option in FRAMECAD Steelwise for Openings

Written by The FRAMECAD Team | Jun 23, 2026

What Is the Mullion Option in FRAMECAD Steelwise?

The Mullion option in FRAMECAD Steelwise allows you to divide a single opening into multiple stacked or offset openings within the same wall panel. It is commonly used to create door-over-window, window-over-window and staggered opening configurations.

Introduction

When creating stacked openings in Steelwise, it is best practice to create one large opening and use the Mullion option to divide it into separate openings. This approach simplifies modelling and helps ensure accurate framing. 

 

How to Create Stacked Openings


Step 1: Create a Single Opening

Create a User Door or User Window sized to cover the total height of the required openings and the width of the largest opening.

Step 2: Open the Opening Editor

Use the List Entity command and open the Opening Editor.

Step 3: Configure the Mullion

Under Construction Method, enter the required settings:

  • Mullion Top Location - Sets the mullion position and the sill height of the upper opening.

  • Mullion Depth - Defines the depth of the mullion.

  • Mullion Webs - Select:

    • No for standard vertical studs

    • Yes for a truss web configuration

Step 4: Send to CAD

Generate the panel in CAD to create the stacked opening arrangement.

Additional Applications

The Mullion option can be used for:

  • Door-over-window configurations

  • Window-over-window configurations

  • Offset or staggered openings

  • Openings with different widths

For staggered openings, create a larger opening and use infill framing to achieve the desired lower opening width.

Conclusion

The Mullion option is an efficient way to create stacked and offset openings in FRAMECAD Steelwise. By creating one large opening and dividing it with a mullion, you can simplify detailing while maintaining accurate framing.

Explore more FRAMECAD Steelwise how-to videos to learn new features, improve your workflows, and get the most from your software.

Frequently Asked Questions About the Mullion Option in FRAMECAD Steelwise

When should I use the Mullion option?

Use the Mullion option whenever you need multiple openings stacked within the same panel.

What does Mullion Top Location control?

It determines the position of the mullion and the sill height of the upper opening.

What is the difference between Mullion Webs set to Yes or No?

No creates standard vertical studs, while Yes creates a truss web configuration.

Can I create openings with different widths?

Yes. The Mullion option can be combined with infill framing to create staggered or offset openings.