Roof Baseline Polylines

Typically the program models the roof plan based on the default settings in the Build Roof dialog and the settings on the Roof tab of the Wall Specification dialog. The program takes this information and the layout of the exterior walls and generates a roof. If you want a roof plan that diverges from the footprint of your building, you can use roof baselines to lay out the roof plan instead.

You can generate roof plane baselines in the Build Roof dialog. Check Make Roof Baseline Polylines (this also checks Build Roof Planes) and click OK. The automatic roof generation process stops short of building the roof planes. A continuous set of roof baselines is created along the outside edge of the main layer of the exterior walls.

Once created, roof plane baselines can be edited like a CAD polyline. See "Editing Closed-Polyline Based Objects". When reshaped, new roofs built from these roof plane baselines follow the new shape even if that shape no longer follows the exterior walls.

Just as roof information can be defined in individual walls, roof information can also be defined in each roof baseline edge. When roofs are built using roof plane baselines, the settings in the roof plane baselines override the settings in the corresponding walls.

To create the new roof using the modified roof baselines, check Use Existing Roof Baselines in the Build Roof dialog and click OK.

Editing Roof Baseline Polylines

Roof baselines can be edited and used as the basis for the generation of a new roof plan. They can be reshaped in 2D like CAD polylines. Like walls, edges can have roof information defined in them. When edited, attached roof plane baselines stay at the same baseline height. If roof planes exist at more than one baseline height, each height generates its own set of roof baseline polylines.

Roof baselines always form a closed area. They cannot be severed, but can have additional joints or corners added.

In addition to length and direction, each segment of a roof plane baseline has embedded roof information that the program uses when modeling roof planes. This is the same information that can be set for walls on the Roof tab of the Wall Specification dialog.

To set roof information for roof plane baselines

Select the roof plane baseline at one edge.

Click the Open Object

edit button to open the Roof Baseline Specification dialog.

The settings in the dialog apply only to the selected baseline edge. Specify one of the following options:

Full Gable Wall

High Shed/Gable Wall

Knee Wall

Extend Slope Downward

You can specify that a particular baseline ends Against Wall, which means that the high edge of a roof plane butts into a wall that continues upward.

Click OK to close the dialog. Roof information is shown along the roof plane baselines. Abbreviations used are: V - vertical (against wall), G -gable/shed, K - knee wall, and L - lower (extend slope downward).

An Example

For a simple example of roof plane baseline editing, consider an L-shaped house, with a rectangular roof. The inner part of the 'L' is a patio that is covered under the same roof.

On the left is the roof plane baseline as it was originally produced and the roof plan it creates.

To model the roof plan shown on the right

Select the roof plane baseline by the bottom segment.

Click the Fillet Two Lines edit button. See "Reshaping Objects".

Click the leftmost segment to fillet the two lines.

A message box displays informing you that "The system must delete intervening lines (those on the inside of the L) to join the two selected lines." Click OK.

You should see the roof line shown in the right side.

Open the Build Roof dialog and select the Build Roof Planes and Use Existing Roof Baseline check boxes to model the roof plan shown at right.