On the Tools menu, click Grid Snap or select Grid Snap on the Grid toolbar. Alternatively, use the keyboard shortcut Alt+G. The grid does not have to be visible on the screen for the grid snap facility to function. When grid snap and angle snap are both enabled, grid snap takes priority.
When grid snap is enabled, the snapping distance will be determined by the grid spacing. The grid spacing is set on the Grid dialog. To open the dialog, click "Grid Setup" on the Tools menu. The grid spacing must be greater than 0.2m but a grid size less than 1m will not be displayed in 3D views.
When you draw a wall or place a window or shade, the software will align the object to the nearest grid line.
If "Wall centre" is selected on the Alignment toolbar and grid snap is "on" then the centre line of the wall snaps to the grid.
If "Wall LHS" is selected then the left-hand side of the wall snaps to the grid, where the left-hand side is determined by the direction in which the wall is drawn.
If "Wall RHS" is selected then the right-hand side of the wall snaps to the grid, where the right-hand side is determined by the direction in which the wall is drawn.