Creating a Mulled Door and Window Unit

Reference Number: KB-00525
Last Modified: July 16, 2015

The information in this article applies to:

Chief Architect Premier or Chief Architect Interiors


I am trying to mull a door and some windows together using the Make Mulled Unit tool, but an Information message keeps telling me:

"All selected openings must be with 24 inches (600 mm) of each other and aligned either vertically or horizontally."

What does this message mean and how can I mull these items together?


Doors and windows can be mulled together to form a wide variety of custom units using the Make Mulled Unit edit tool.  In order to use this tool, however, a couple of conditions must be met:

  • The openings in question cannot be more than 24 inches or 600 mm apart.

  • The openings cannot be overlapping.

  • The openings in question must be aligned vertically or aligned horizontally - but not both.

Bearing these rules in mind, doors and windows can be mulled into a single unit quickly and easily, even when the unit has multiple rows of windows.


To create rows of stacked windows

  1. Open the plan in which you want to create a mulled window unit.

    In this example, a simple rectangular structure is used.  The ceiling height is set at fifteen feet so there is plenty of room for placing rows of windows above one another.

  2. Place a door and as many windows as you will require for your first row of units and edit the door and windows' sizes and types as needed. 

    • In this example, a 36" wide glass door is positioned between two 24" wide Fixed Glass windows. The three objects are 4" apart.

  3. Select 3D> Create Orthographic View> Cross Section/Elevation  from the menu, then click and drag a camera arrow towards the windows.

  4. Click the Select Objects button, then click on one of the windows to select it.

    • Hold down the Shift key on your keyboard and click on the remaining windows to add them to your selection set.

    • When multiple objects are selected, the total number is stated at the bottom of the program window, on the left side of the Status Bar.

  5. When all of the windows are selected, click the Transform/Replicate Object  edit button. In the Transform/Replicate Object dialog:

    • Check the box beside Copy and set the Number of Copies to 1;

    • Check the box beside Move and set the Z Delta value to a positive value such as 24".

    • Click OK to close the dialog and make one copy of the selected windows 24" above the originals.

  6. With the newly created windows still selected, click the Open Object edit button and specify these new windows' Height, then click OK.

    • In this example, a Height of 18" is used.

  7. Use the Transform/Replicate Object edit tool to make an additional copy of one of your second row windows over the door:

    • Make one copy as described above;

    • If the window is placed in a wall that runs horizontally in floor plan view, specify a Move distance in the X Delta field;

    • If the window is placed in a wall that runs vertically in floor plan view, specify a Move distance in the Y Delta field;

    • If the window is placed in a wall drawn at an angle in floor plan view, you can specify a Move distance in either Delta field.

    • Specify a distance equal to the Width of the window plus its distance from the door - in this example, 28".

  8. Use the new window's edit handles to increase its width so it matches that of the door.

  9. Repeat these steps as needed to produce additional rows. 

    • In this example, the middle window is replicated once more, 40" above the original.  This top window is specified as 92" wide, 36" high, with a 28" high Trifoil Arch.

Once the door and its side and transom windows are in position, they can be mulled.


To create a mulled unit

  1. Click the Select Objects  button, then click on the door to select it.

    • Hold down the Shift key on your keyboard and then click on the two windows on each side of the door to add them to the selection set.

  2. With these three vertically aligned objects selected, click the Make Mulled Unit edit button.

    • Notice that the three objects no longer have separate labels and their casings merge.

  3. Next, use the Shift key to group-select the three windows in the middle row and click the Make Mulled Unit edit button.

  4. With the newly created middle mulled unit selected, Shift + select the top window.  With these two vertically aligned objects selected, click the Make Mulled Unit  edit button.

  5. Now, with the mulled unit consisting of the two top rows selected, Shift + select the bottom mulled unit and click the Make Mulled Unit  edit button.

  6. By default, mulled units that include a door are treated as doors for the purposes of producing schedules and materials lists.  If you would prefer that this unit be treated as a window:

    • Select it and click the Open Object  edit button.

    • On the Options tab of the Mulled Unit Specification dialog, uncheck Treat as Door

  7. This mulled unit can now be added to the library for use in other plans.