Crop Elements to Single-plane Roof

To crop an element to a Single-plane roof, use the Design > Roof Extras > Crop to Single-plane Roof command.
The Crop to Single-plane Roof function is not associative. Crop to Roof, available for Single-plane roofs only, creates a changed Wall geometry which is static.
Note: A similar function is the Crop Zone command, which crops Zone volume using surrounding elements, including single-plane Roofs.
The Crop to Single-plane Roof command is available only if at least one roof or one element of the above types is selected.
2.
Go to Design > Roof Extras > Crop to Single-plane Roof to bring up the Crop to Single-plane Roof dialog box.
Crop Element Top: Crop the part of the element(s) above the roof
Crop Element Base: Crop the part below the roof.
5.
Click Crop and view the result.
at Design > Roof Extras
Exception: A crop on a Slab can only be undone through the regular ARCHICAD Undo function (Edit > Undo).
Set Wall/Column Top to highest Point at the bottom of the Crop to Single-plane Roof dialog box.
(If you chose Crop Element Base, the checkbox refers to the Wall/Column’s base elevation (lowest point)).
The Undo All Crops command will have a different effect depending on the checkbox status:
If you set the Crop operation to recalculate the Wall/Column’s height value (if the checkbox was active), then the Undo All Crops will only recreate the Wall/Column up to the maximum cropped height, as shown in this image:
If you did not check the box, then Undo All Crops will recreate the original Wall height.
Slabs can also be cropped by the lower or upper slope of roofs with the help of the Design > Roof Extras > Crop to Single-plane Roof command.
You can use remote roofs, and even roofs on other stories whose outline is shown on the given story, to crop elements to the plane of that particular roof. In this case, the Crop to Single-plane roof command does not work (it only works if the elements intersect each other.) However, you can use a keyboard shortcut when cropping with a remote roof.
2.
Select the elements you intend to cut, then Ctrl-click (Cmd-click) an edge or a node of the roof you want to cut them with. The reverse procedure will also work: select the roof you want to cut with and Ctrl-click (Cmd-click) the individual elements you want to be cut.
Note: The Wall/Beam/Column is cut whether it is under a Roof or not. Be sure to set a sufficient height for the original rectangular Walls/Beams/Columns so that they are cut correctly.