Specifying the Depth of Floor Joists

Reference Number: KB-00049
Last Modified: July 16, 2015

The information in this article applies to:

Chief Architect Premier


How do I set the joist depth for one particular room?


Floor platform structure is specified on a floor-by-floor basis in the Framing Defaults/Build Framing dialog.  You can also specify floor structure information on a room-by-room basis in the Room Specification dialog. 

In addition, you can also specify the depth of an individual floor or ceiling joist in its specification dialog; however, resizing a joist in this manner will not affect the space allotted for it in the floor or ceiling platform that it is located in.

It is recommended that you specify all structural information, including floor and ceiling heights and platform thicknesses, before you build a roof or generate framing.

To specify joist depth for an entire floor

  1. Select Edit> Default Settings  from the menu, click on Framing in the list to highlight it, then click the Edit button.

  2. In the Framing Defaults dialog for the current floor:  

    • The floor framing information for each floor is specified on the panel for the floor below.  
      For instance, to specify the floor framing defaults for Floor 2, select the Foundation panel.

    • When you are satisfied with your settings, click OK to close this dialog, then click the Done button to close the Default Settings dialog, as well.

  3. When you build floor framing for the current floor, all floor joists will have the depth that you specified above.  

To specify joist depth for an individual room

  1. Click the Select Objects  button, then click in an empty space in a room to select it.  

  2. Click the Open Object  edit button, and on the Structure panel of the Room Specification dialog:  

    • Click Edit next to Floor Structure (L) .


    • In the Floor Structure Definition dialog, change value for Layer 2: (the Fir Framing layer) Thickness.

    • Click OK to close the dialog and apply your change.

  3. When you build floor framing for the current floor, the floor joists in this room will have the depth that you specified rather than the default depth.  

To specify the depth of an individual joist

When a joist is generated automatically or drawn manually, it's initial depth will be based on the default joist depth for the current floor or the depth specified for an individual room on that floor.  Once a joist is created, you can edit its depth in the Framing Specification (Floor Joist) dialog.  Bear in mind, though, that it may not fit within the platform that it was placed in.

  1. Click the Select Objects  button, then click on a joist to select it, then click the Open Object  edit button.

  2. On the General panel of the Framing Specification (Floor Joist) dialog:


  • Uncheck Raise/Lower.

  • Move the radio button next to Lock to the Depth field.

  • Specify the desired Top Height and Bottom Height Values to create the desired Floor Joist depth

  • Click OK to apply the changes.