AutoCAD Architecture - Creating custom ceiling grids
A custom grid with 48" spacing left to right and alternating 4" spacing and 48" spacing bottom to top is possible. If the 4" channels need to not have the grid lines running through, you would have to do something to hide that, such as using a Mask Block. Does the grid actually not run across the 4" part? I have seen similar ceilings, such as Armstrong TechZone, but they have a grid in the narrow part at least every 4'.
The X Axis spacing is a 4'-0" Repeat.
The Y Axis spacing is set to Manual, with spacings of alternating 4'-0 and 6". As the name implies, Manual requires doing some manual work for each grid to get it to show that way. If your ceiling areas are in several semi-uniform sizes, you could set up grids for each size and then copy them as needed, rather than setting each one up from scratch.
You can, of course, set a Space or a closed Polyline as a boundary. I would advise that you not make one giant grid, and use the boundary to get the size you need for each room. It will look the same, but AutoCAD Architecture will still keep track of all of the grids/cells beyond the clipping boundary, and making copies of a grid large enough to cover your biggest ceiling area for every ceiling area may cause performance issues. Some years back, someone in my office complained about how slow one file was. After a lot of investigation, we discovered that someone decided it was easier to copy one really large ceiling grid and then set a boundary to trim the excess. This added a very large amount of unnecessary geometry that had to be tracked by the program, even though it was not seen. Reducing all of the ceilings to be just big enough to cover the area brought the file back to the expected performance.
I attached the file I used to create the image above, authored in AutoCAD Architecture 2022 (2018 file format).
