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Reference Plane options for Roofs

Laszlo Nagy
Community Admin
Community Admin
Slabs now have Reference Plane, which can be set to Top, Bottom, Core Top, Core Bottom. Additionally, we have commands to modify the reference plane location of an existing Slab.

I wish to have these same options available for Roofs as well.
One common scenario where this would be helpful can be seen in the following thread:
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AMD Ryzen9 5900X CPU, 64 GB RAM 3600 MHz, Nvidia GTX 1060 6GB, 500 GB NVMe SSD
2x28" (2560x1440), Windows 10 PRO ENG, Ac20-Ac27
This feature should be added if for no other reason than it reinforces the long-held Graphisoft ArchiCAD ethos of all tools working the same way.

Similarly, slabs and roofs could be interchangeable while walls, beams and columns could inherit x:y sloping parameters.

This shouldn't be an incremental change stretched out to the release of ArchiCAD 23.

worksheet and detail windows are the same thing with different names. Why isn't that the case with the building 'primitives' as well?
Think Like a Spec Writer
AC4.55 through 27 / USA AC27-5030 USA
Rhino 8 Mac
MacOS 14.5
Roof Planes also need to follow the same rules for Priority Based Connections as Slabs. I've recently discovered this is not the case.
Think Like a Spec Writer
AC4.55 through 27 / USA AC27-5030 USA
Rhino 8 Mac
MacOS 14.5
Eduardo Rolon
There is a reason that Roofs do not follow PBC's like Slabs but I can't find the reference. Because of that they included the following command:
Merge Elements: Roofs, Shells, Morphs
Use the Connect > Merge Elements command to enable priority‐based intersections among any number of Roof/Shell/Morphs and other elements. (At least one of the merged elements must be a Roof, Morph or Shell.)
Note: Alternatively, you can use Roofs and Shells to trim other elements (not just merge them): this is another way to enable priority‐based connections for Roofs/Shells, as well as physically trimming the target element.
Eduardo Rolón AIA NCARB
AC27 US/INT -> AC08

Macbook Pro M1 Max 64GB ram, OS X 10.XX latest
another Moderator

Barry Kelly

Not only should we be able to set the pivot line (reference plane) to the top, bottom, core, etc., but the height for the multi-plane geometry (additional pivot lines) should be in the same plane.

Currently we have the main pivot line on the bottom surface but the heights for addition levels are measure to the top surface of the roof.
If I am trying to pitch that roof over a wall I know the height to the underside of the roof - not the top surface that will change depending on the roof thickness and pitches.




One of the forum moderators.
Versions 6.5 to 27
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11
I could do with this wish right now. Working on a project where I am adding new roof planes; whenever a roof thickness is amended I then have to spend ages adjusting the new roofs up or down to realign the top surface.
Apple iMac Intel i9 / macOS Sonoma / AC27UKI (most recent builds.. if they work)

August 2022, Archicad 25 still doesn`t have this implemented....Should we wait another 8 years?

Cause i assume AC 26 won`t have this "feature " either.

Archicad 23/25/26 NL , MacOS 13.4.1 (c) on MacStudio M1 Max