Creating Roof Trusses


Reference Number: KB-00981
Last Modified: January 30, 2019

The information in this article applies to:

Chief Architect Premier



QUESTION

How do I create a roof truss?


Set of Roof Trusses


ANSWER

Drawing roof trusses in Chief Architect is as simple as drawing and replicating a line - as long as certain conditions are met. Roof trusses in the program are defined by the position of one or more roof planes above and one or more ceilings below, so both must be in place before a truss is drawn.

  • The roof and ceiling planes can be automatically generated or manually drawn.   

  • The ceiling can be composed of the default flat ceiling generated in each room by default, of manually-drawn planes created using the Ceiling Plane tool, or of a combination of the two.  

  • There must be space between the roof and ceiling in which a truss can generate. Trusses cannot be generated along the line where the roof and ceiling come together, usually on a bearing wall.


To create roof trusses

  1. Open the plan in which you would like to create roof trusses, or select File> New Plan  to open a new plan.   

    20' by 30' building

    • In this example, a simple 20' x 30' plan is used.  


  2. With the Select Objects  tool, Group Select the left and right walls, then click the Open Object  edit button.


  3. On the Roof panel of the Wall Specification dialog that opens, select Full Gable Wall, then click OK.

    Wall Specification dialog with Full Gable Wall selected on the Roof panel


    For additional information on building an automatic gable roof, visit the "Generating Automatic Hip and Gable Roofs" article linked in the Related Articles section below.


  4. From the menu select Build> Roof> Build Roof .

    • On the Roof panel, put a check next to Build Roof Planes

    • Put a check next to Trusses (no Birdsmouth)

    • Verify pitch and overhang settings, then click OK.

      For the purposes of this article, an 8:12 pitch is specified with an 18" overhang.

      Build Roof dialog with Build Roof Planes and Trusses selected

      The Trusses (no Birdsmouth) setting sets the roof height so that the bottom edge of the truss top chord is flush with the top of the wall and roof plane thickness is based on the default Top Chord Depth set in the Framing Defaults. If it is not checked, the roof plane thickness is determined by the rafter Depth setting in the Framing Defaults.

      If you plan to use both trusses with rafters, leave Trusses (no Birdsmouth) unchecked so that the rafters’ depth can be accommodated. Please review the "Mixing Trusses with Stick Framing" section of the Reference Manual for more information.


  5. Select Build> Framing> Roof Truss  from the menu, then click and drag a line at a location where you would like a roof truss. 

    • A Message may appear asking "The layer "Framing, Roof Trusses" is not displayed. Do you want to turn on the display of this layer in the current view?" Click Yes to display the Roof Trusses layer in this view.

    One truss drawn two feet in from right side of building


To replicate trusses across a structure

  1. Move the first truss into position using Temporary Dimensions.

    • Make sure that Temporary Dimensions  are enabled. If they are not, you can enable them by selecting View> Temporary Dimensions .

    • Click the Select Objects  button, then click on the truss to select it. 

    • If you select a roof plane, ceiling plane, or other object instead of the truss, click the Select Next Object  edit button or press the Tab Key on your keyboard until the truss is selected. 

    • When the truss is selected, a dimension will depict how far it is from a perpendicular wall. Click on the dimension, type 0" in the text field, and press Enter.

      Moving the truss using dimensions

    • The truss will move so that its outer edge is aligned with the outer edge of the framing layer of the wall.

      Truss moved to outer edge of the framing layer of wall


  2. With the truss still selected, click the Multiple Copy  edit button.  


  3. By default, the Multiple Copy interval for trusses is 24" (600 mm). To change this interval, click the Multiple Copy Interval  edit button and specify the desired Primary Offset value for trusses in the Multiple Copy dialog, then click OK.  

    Multiple Copy dialog with 24 inches set for All Trusses Primary Offset


  4. Click and drag the truss's middle Move  edit handle towards the other end of the structure. As you drag, new trusses will be created at regular intervals. Release the mouse button to complete the command.  

     Several trusses appearing accross the building


  5. Select 3D> Create Perspective View> Perspective Framing Overview  to see the results.  

    Framing Overview showing all the trusses


To create a reduced gable or an end truss

  1. With the Select Objects  tool, select the trusses on either end of the gable and click the Open Object edit button.

    Holding the Shift key while selecting allows you to group select multiple trusses.


  2. On the General panel of the Roof Truss Specification dialog that opens, put a check next to End Truss as well as Force Truss Rebuild.

    • Check the Reduced Gable box in this dialog as well to lower the top chord of an End Truss so that lookouts can pass over the truss.

    • Click OK to regenerate the Truss


  3. Select 3D> Create Perspective View> Perspective Framing Overview  to see the results.

    Perspective Framing Overview showing all the trusses including two End Trusses