To create a ceiling grid pattern in Revit, follow these steps:
1. Open your project file and set the view to 3D view.
2. Click on the Level button in the Navigation Bar, and select Ceiling Grid from the list that appears.
3. Double-click on the floor plan surface where you want the grid to appear, or use the enter key to select it.
4. On the Ceiling Grid tab, click on Add New Layer at the top of the window.
5. In the Layers dialog box that appears, type Grid into the Name field, and then click on the OK button.
6. In the newly created layer, reduce its width to zero by clicking on its Maximize menu button (the three vertical dots in the upper left corner), and then selecting Reducing Width from its available options. If you have more than one grid layer, further reducing their width will add more grids