The Trim to Roof/Shell command allows you to connect Roofs or Shells with each other or with other model elements in any ARCHICAD model window. The result is a more complex structure whose elements are trimmed precisely to each other, although they remain separate elements.
Elements trimmed to each other using this command will also be merged, and will intersect based on their skins intersection priorities.
The trimming element is always either a Roof or a Shell. A Roof or Shell can trim any model element (e.g. Wall, Beam, Column).
Roofs and Shells trimmed to each other act as a single body when trimming other model elements.
Elements trimmed to each other are associative: a change to any element will immediately affect all the connected elements. For example, if you change the Roof pitch, the Wall that it trims will change accordingly.
Note: In contrast, the Crop to Single-plane Roof function (known as Trim to Roof in earlier ARCHICAD versions), is not associative. Crop to Roof, available for Single-plane roofs only, creates a changed Wall geometry which is static.
Once you have created a trimming relationship, the elements involved are connected. If you want to change this relationship, you don’t have to undo the connection; just do the Trim operation over again.