Creating Scissor Trusses
| Reference Number: KB-00068 Last Updated: 10-03-2013 08:14 AM
The information in this article applies to:
How do I create scissor trusses?
In Chief Architect, roof trusses are generated in the space between the roof planes above and ceiling planes below. When a vaulted ceiling has a different pitch than the roof planes above, scissor trusses are produced.
To create a vaulted ceiling
- Launch Chief Architect and choose to Open the Chief Architect plan in which you would like to create scissors trusses.
In this example, a simple 20' x 30' rectangular plan with a gable roof is used.
- Using the Select Objects tool, click in the room that will have a vaulted ceiling to select it, then click the Open Object edit button.
- On the Structure tab of the Room Specification dialog, uncheck the box beside Ceiling over this room, then click OK.
- To make it easier to draw ceiling planes, select Tools> Display Settings> Display Options from the menu.
In the Layer Display Options dialog for your currently active layerset:
- Scroll down to the Roof Planes layer and remove the checkmark in the Disp column.
- Click OK to close the dialog and turn off the display of the roof planes in your plan.
- Select Build> Roof> Ceiling Plane from the menu.
To create a ceiling plane:
- Click and drag a baseline along a wall defining the room that will have a vaulted ceiling.
- For best results, the baseline should be above the outside edge of the framing layer of that wall.
- When the baseline is complete, click once in the room to set the ceiling plane's ridge.
- Click on the ceiling plane to select it, then use the edit handles that display to stretch it across the room to the inside surfaces of the gable walls.
- In this example, two ceiling planes will form a ridge in the center of the room, so make sure the ridge edge of this plane does not extend past the middle of the room.
- With the ceiling plane still selected, click the Open Object edit button.
On the General tab of the Ceiling Plane Specification dialog:
- Make sure that the Inside bottom height is locked.
- Specify the desired Pitch for your vaulted ceiling.
- Click OK close the dialog and apply the change.
- Repeat steps 2 through 4 to create a second ceiling plane opposite the first one.
- Click on the ridge edge of one of the ceiling planes, click the Join Roof Planes edit button, then click the ridge edge of the other ceiling plane. The two ceiling planes will join at the center of the room.
- If you wish, you can turn the display of roof planes back on in the Layer Display Options dialog.
To create scissor trusses
With both the ceiling and roof planes in place, you can now create roof trusses.
- Select Build> Framing> Roof Truss from the menu.
- Click and drag to draw a roof truss perpendicular to the ridge line of the roof and ceiling planes.
- Click on the truss to select it and move it so that it is just inside one of the gable walls.
- With the truss still selected, click the Multiple Copy edit button, then click and drag the truss's Move edit handle to create copies at regular 24" intervals.
: To specify a different interval, first double-click the Multiple Copy
edit button and specify the desired copy interval for trusses in the Multiple Copy
- To see the results, select 3D> Create Perspective View> Framing Overview from the menu.
Article Number 416: How to create exposed trusses in a vaulted ceiling
Article Number 933: How to create an attic truss
Article Number 981: How to create roof trusses