Last updated July 28, 2026
CGRID lays out a suspended ceiling grid inside a room you define, and centres it. That centring is the whole point: a ceiling grid started from a corner leaves a sliver of a tile at the far wall, whereas one centred on the room gives you matching cut tiles at both edges, which is what a ceiling is supposed to look like.
It is by Harold E. Davis, version 1.0, dated 13 April 1992.
It uses a fixed layer name
The grid is drawn on a layer called EECEILING, which is written into the code rather than asked for. That is somebody’s office standard from 1992, and it is almost certainly not yours.
Nothing breaks — the layer is created if it does not exist, and the grid appears on it. But you will end up with a stray layer in your drawing unless you edit the name first, and on a project with a layer standard that matters.
The name appears in the file as plain text and changing it is a quick edit. Worth doing before the first run rather than cleaning up afterwards.
Note also that the grid is drawn as individual lines rather than as a hatch or a block. That makes it easy to trim around light fittings and diffusers, which is what you will spend the next hour doing anyway, but it does mean a lot of objects on a big ceiling.
It cleans up after itself if something goes wrong
Worth crediting, because it is more careful than most files of this vintage.
The routine installs its own error handler, and that handler does something unusual: as well as restoring the previous handler and resetting the snap base point, it issues an UNDO Back. So if the routine fails or you cancel halfway through drawing a grid, the partial grid is rolled back rather than left in the drawing for you to erase by hand.
It also reports what went wrong by name and tells you the program aborted, rather than dropping you at a bare error message.
That UNDO Back is worth understanding before you use it, though. It rolls back to the last undo mark, so if you had other work in progress at that point it will go too. Run it as a discrete operation rather than in the middle of something else.
Command reference
The file defines a single command, CGRID.
Note that the ArchLisp collection on this site also includes a ceiling grid routine, under the command CE. They are different programs solving the same problem, so it is worth trying both and keeping whichever suits your ceilings.
How to load it
Unzip the download and load CGRID.LSP with APPLOAD, after editing the layer name if you want it on your own standard. No support files. Our AutoLISP guide covers loading.
Step-by-step usage
- Have the room outline drawn, and save your work — the error handler’s undo can reach further back than you expect.
- Type CGRID.
- Define the room and give it the tile size and orientation it asks for.
- The grid is drawn, centred, on the ceiling layer.
- Trim it around any fittings.
Compatibility notes
April 1992, so written-for rather than tested-on. It draws lines and manipulates the snap base point, neither of which has changed, and the error handling suggests an author who tested his own work.
Plain AutoLISP with no dialog boxes and no Express Tools calls, so nothing requires the full product; LT users on LT 2024 or later, the release that brought AutoLISP to LT, should be able to run it. See what runs on AutoCAD LT. Expect imperial tile sizes to be the assumption of the era — the standard American ceiling tile is 600 by 600 millimetres in metric terms, but was thought of as two feet square.
Download
| Name: | Ceiling Grid |
| Description: | A routine that draws a ceiling grid centered on the user defined room. |
| Type: | AutoCAD AutoLISP Routine |
| Author: | Harold E. Davis |
| File Size: | 2 Kb |
| Cost: | Free |
| Worked on: | AutoCAD |
| Download File: | Cgrid.zip |
Related routines
- ArchLisp — includes a different ceiling grid routine.
- HVAC Suite — the ductwork above the ceiling.
- BATT — insulation for the same section drawings.