If levels are the vertical skeleton of a project, grids are the horizontal one. A grid is a named reference plane that shows up as a line in your floor plans, and it is how you locate everything in plan: columns sit on grid intersections, walls run along grid lines, beams span between them. This is the part that feels familiar coming from AutoCAD, because you have drawn column gridlines on a 2D plan plenty of times. The difference in Revit is that these lines are smart. Number them once and the numbers follow you everywhere, move one and everything aligned to it moves too, and they carry through the whole model instead of being redrawn on every sheet.
Grids live in plan, the opposite of levels
Here is the contrast worth holding onto. You could only make levels in an elevation or section, never in a plan. Grids are the reverse: you create them in a floor plan view. It makes sense for the same reason levels did. A grid is a vertical plane, so looking down on it from a plan is exactly where you see it as a line and can place it.
So before you start, set up your levels first, then open a plan to lay out grids. In the Project Browser, expand Floor Plans and double-click your lowest level, often Level 1 or whatever you renamed it to. That is your workspace for the grids.
There is a practical reason for the levels-first order too, and it ties into the trap further down: a grid drawn in plan stretches itself vertically to span your levels, so having the levels in place first means the grids show up on every floor instead of just the one you drew them on.
Creating grids
With a plan open, the tool is on the ribbon under Architecture tab → Datum panel → Grid. It also sits on the Structure tab → Datum panel → Grid, the same tool, and that is the one to reach for if you came in through structures.
There are two ways to place a grid, the same pair you used for levels:
- Draw it. Click a start point, move the cursor in a straight line, and click again to finish. As you draw, the heads and tails of new grid lines snap into alignment with the ones already there.
- Pick Lines. Choose Pick Lines from the Draw panel, then click an existing line such as a wall, and Revit lays a grid right along it. Handy when the geometry is already there to trace.
There is also a Multi-Segment option in the Draw panel for the rare grid that needs more than one straight segment. Leave it alone for normal work. One thing to know if you ever use it: multi-segment grids cannot be tracked with the Copy/Monitor tool, which matters later when you coordinate with a linked model.
Revit numbers each grid automatically as you draw, 1, 2, 3, and so on. To change a value, click the number in its bubble, type the new one, and press Enter.
Numbers one way, letters the other
The standard structural convention is grids running in one direction numbered (1, 2, 3) and grids in the other direction lettered (A, B, C), so any point in the building has an address like B3. Revit supports this directly. If you change a grid’s value to a letter, every grid you draw after it carries on alphabetically on its own. So set the first grid of your second direction to “A”, and the next ones become B, C, D without you typing them.
A small thing that saves grief later: as grid lines align, selecting one shows a small lock at the aligned end. That lock means the heads are tied together, so if you drag the extent of one grid, all the aligned ones follow. It keeps your bubbles in a tidy row instead of drifting out of line.
The trap: grids that vanish from another floor plan
This is the grid version of the level-head trap, and it catches everyone once. You draw your grids on Level 1, they look perfect, then you open the Level 2 plan and some of them are missing. Nothing is broken and nothing got deleted. The cause is extents.
Every datum, grids included, has two kinds of reach. The 3D extent is how far the grid stretches through the model vertically, and it decides which views the grid even reaches. The 2D extent is how long the line looks in one particular view, and changing it only touches that view. When a grid does not appear in a plan, it is almost always because its 3D extent is too short to reach up to that level.
You can see this plainly in a 3D view: select a grid and its 3D reach is drawn out, and you will spot the short one not tall enough to hit the upper level. The quickest fix is to select the missing grid, right-click, and choose Maximize 3D Extents. Revit stretches it to the full bounds of the model, and it reappears on the floors it was missing from.
One more tell to read correctly. When you select a grid end, the little control circle shows which extent you are about to drag: a hollow circle means you are changing the 3D extent (affects all views), a filled one means 2D (this view only). If you only want to shorten how a line looks on one plan without making it disappear elsewhere, switch that end to 2D first, then drag. And if you have tidied a grid’s length in one view and want the other plans to match, select it and use Propagate Extents from the Datum panel to copy that 2D look to the parallel views you pick.
That is grids set up: drawn in plan, numbered and lettered by convention, aligned so they move together, and stretched to reach every floor. With levels giving you height and grids giving you position, the skeleton of the model is in place. From here you start hanging real elements on it, and the first one that snaps straight to your grid intersections is the structural column.
If you are still weighing up whether the move into BIM is worth it, the civil engineer to BIM roadmap lays out the whole path, downsides included.