This 21 minute ArchiCAD training lesson explores the methods that may be used in ArchiCAD 15 and later versions to connect roofs to each other, focusing on adding a gable extension to a simple hip roof system.
In ArchiCAD 15 and later, connecting roofs has become much easier in many cases. In addition to the use of the multi-plane roof option, which simplifies creation and editing of roofs with a single plate height, the Connect command generally makes fast work of trimming walls and cleaning up roof elements to each other. However, there are some limitations in the multi-plane roof tool, so there are times when one may need to split up these roofs into single-plane roofs in order to get the highest quality and most flexible result.
After a basic rectangular building is drawn with a hip roof, a gable extension is created. To make this gable extension face the proper direction (ridge line going from the top of the screen to the bottom, rather than side to side), the new roof system is drawn temporarily elongated, then the pivot line polygon is adjusted using the pet palette. To connect this new roof system to the main roof, instead of using the Command-click or CTRL-click method, both roofs are selected and then right-clicked to activate the Connect > Trim Elements to Roof or Shell command. The same command is used to trim the walls to the roofs, instead of using the older Solid Element Operations command.
The gable extension is duplicated twice, each time with a different pivot line height. The roofs are easily cleaned up to each other using the Connect command.
When the gable extension has the same plate height as the main roof, the new roof components can actually be created by modifying the main roof pivot line to follow the bump out of the walls, using familiar pet palette editing commands for the pivot line polygon. The hip extension can be changed to a gable by using the Custom Plane Settings option for that edge of the pivot line.
This flexibility in terms of editing the pivot line polygon also makes easy work of moving the gable extension to line up with the hip end of the main roof.
There are some parts of the connection between roofs that can get tricky, as the choice of using pivot lines or contour lines for the Trimming Body can cause significantly different results, perhaps improving some parts of the model or plan drawing in some cases while compromising other parts of the design. Sometimes it may be necessary or desirable to break up a multi-plane roof into single plane roofs, and edit the roof contours manually or with the help of the traditional Command-click or CTRL-click methods.
Since the Command-click / CTRL-click method does not work with multi-plane roofs, a workaround is demonstrated that involves temporarily splitting up a multi-plane roof to create certain changes in the model, then undoing the split while retaining the changed parts on the clipboard for pasting into place moments later.
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