Select a roof truss or group of roof trusses and click the Open Object 
edit button to open the Roof Truss Specification dialog.
The Roof Truss Specification dialog allows you to redefine parts of an existing truss or group of trusses. Some settings affect only individual trusses, such as gable trusses, while others affect the whole group.
The shape or volume of a roof truss is controlled by the roof planes above it and the ceiling planes below it. It cannot be changed from this dialog.
Top Chord - Specify the depth.
Bottom Chord - Specify the depth.
Webbing - Specify the depth.
Check Require Kingpost to require a vertical webbing member from the roof peak to the bottom chord.
If this is not checked, a vertical member may still be supplied, depending on what is needed to support the chords at or closer than the specified maximum spans.
Following is a truss detail. The lower truss was a copy of the upper truss, with Require Kingpost checked.
End Truss - Select the check box to replace the webbing with vertical members positioned and spaced on center the same as the wall studs below. The framing reference is used for this exactly as it is for wall studs. If an end truss is in the same position as a gable attic wall, it replaces the framing that would otherwise be produced for that wall.
Drop Hip Truss - Select the check box to lower the flat top of a truss in the hip area of a roof.
The flat top is lowered so that common rafters and hip ridges can pass over and be supported by it. The amount that the top chord is lowered is derived from the rafter Depth on the Roof tab of the Framing dialog. Because both common rafters and hip ridges must pass over this truss, the ridge depth should be set equal to that of the rafter depth. For an illustration of a Drop Hip truss, see "Drop Hip".
Energy Heel - Select the check box to model a truss with an energy heel, which removes the bottom chord from the overhang area. For this to be modeled, the Raise Off Plate value in the Build Roof dialog must be equal to or greater than eight.
To provide more space for ceiling insulation at the exterior walls, roofs are sometimes raised off of the top plate with an energy heel. When a truss is built for such a roof, a vertical member is added over the supporting wall to prevent the bottom chord from extend
ing into the overhang area as far as the end of the rafter, or until it intersects the rafter.
Reduce Gable - Select the check box to lower the top chord of the gable truss so that lookouts may pass over the truss. Any overhang is removed from a reduced truss. You can supply this overhang with short rafters drawn at the ends of the truss.
Attic Truss - Check this box to specify an attic truss
Maximum Span - Specify the maximum horizontal distance between supports along the Top Chord and along the Bottom Chord. If these are equal, the truss webbing often appears more regular.
The placement of webbing inside a newly drawn truss is controlled by the Top Chord and Bottom Chord settings under Maximum Span in the Trusses tab of the Framing dialog. The webbing is for representational purposes only, not for engineering.
Thickness - Select the thickness, or truss width in floor plan view. This setting overrides default settings.
Maximum Height - Specify the maximum height of selected truss.
Force truss rebuild - Select the check box to update trusses with the new settings in this dialog when you click OK.
Lock Truss & Webbing - Check this box to lock size and configuration of truss. A locked truss which has been relocated will maintain its original settings, and may no longer fit properly if the new roof and ceiling conditions are different from the original.
For more information about the Line Style tab, see "Line Style Tab".
For more information about the Fill Style tab, see "Fill Style Tab".
For more information about the Materials tab, see "Materials Tab".
|
Chief Architect www.chiefarchitect.com |
