If you sketched a curtain wall without automatic grids, you can add grids manually.
Each section of the grid (design unit) is filled with a separate curtain wall panel of the selected type.
When you place curtain grids, they snap to evenly spaced intervals on the curtain wall. For example, as you drag the cursor over a panel, it snaps to the midpoint or to the 1/3 mark of the panel.
When you place curtain grids on walls, sloped glazing, and curtain systems, the curtain grids snap to visible levels, grids, and reference planes. In addition, curtain grids snap to other curtain grids when you select a common corner edge. For example, if you place the cursor on a joined edge between 2 curtain walls, the new curtain grid snaps to an existing curtain grid.