Structural floors in Revit are slabs drawn with the Floor: Structural command on the Structure tab, with the Structural check box already ticked in the Properties palette. The geometry is the same as an architectural floor, but that single tick decides whether the slab reaches the concrete quantity schedule and whether it can host reinforcement.
The second thing that trips people up: the top face sits on the level, and the thickness hangs below it. A bathroom slab that must sit lower is dropped with a parameter, never dragged by hand.
This article covers one full storey of flat elements: the slab, the dropped area, the openings and the bearing walls. Fifteen steps in the order you click them, captured on Revit 2027.2 with the English interface. For the architectural angle, see how to draw a floor in Revit; for the whole documentation workflow, see the Revit Structure course.
Structural floors in Revit versus architectural floors
The Floor button on the Structure tab opens a menu with three entries, not one.
| Entry | What it does |
|---|---|
| Floor: Structural | A load-bearing slab. Structural is ticked, so it hosts rebar and appears in concrete schedules |
| Floor: Architectural | Same geometry, no structural role. Used for finish layers |
| Floor: Slab Edge | Creates no slab at all. It adds a moulding that runs along an existing slab edge |
The first two produce the same kind of object: a system family called Floor. They differ only in the default state of the Structural tick, so any slab can change role at any time.
A floor is not a loadable family the way a column or a beam is. Its build-up is declared inside the project through a layer table, which is why every slab thickness needs its own type.
What you need before you start
You need a model that already has levels, grids, columns and beams. The three previous articles in this series build exactly that.
- Grids and levels in Revit — the setting-out system comes first.
- Structural columns and beams in Revit — the slab sits on this frame.
- A Revit structural template — if you are starting from a blank file.
The screenshots come from a four-storey house: levels 1F ±0.00, 2F +3.90, 3F +7.50, 4F +11.10 and RF +14.00, with a 120 mm slab whose type is named S120.
How to create a structural floor in Revit: the first eight steps
Step 1 — Open the structural plan of the storey
In the Project Browser, open the Structural Plan of the storey you are modelling. A structural view has its Discipline set to Structural, so it hides non-bearing elements and lets you read the beam layout underneath. Open the wrong view and the slab lands on the wrong storey.
Step 2 — Launch Floor: Structural from the Structure tab
Click the Structure tab, go to the Structure panel, click the small arrow under Floor and pick Floor: Structural. The ribbon switches to the contextual tab Modify | Create Floor Boundary, the drawing fades back and every other command is locked out.
Step 3 — Duplicate the floor type and name it after the thickness
In the Properties palette, click Edit Type.
Click Duplicate before changing anything, otherwise every slab of that type in the project follows the change. Name the type after its thickness, for example S120. Vietnamese drawing sets read that convention easily, and the slab tag prints the type name straight onto the plan.
Default Thickness is greyed out because it is the sum of the layers. Structural Material is greyed out as well: the structural material comes from the layer you flag in the next step.
Step 4 — Declare the concrete layer and its material
Click Edit… on the Structure row.
A structural slab needs one layer only: the Structure row between the two Core Boundary rows. Type the real thickness into Thickness and pick concrete in Material.
| Column | Why it matters |
|---|---|
| Structural Material | Flags the load-bearing layer. Concrete quantity schedules read this flag |
| Variable | Lets that layer change thickness, which is what makes a slope possible in step 10 |
| Core Boundary | Both rows are always 0 thick; they only mark where the core starts and ends |
Keep the finish layers in a separate architectural slab and your concrete take-off stays clean.
Step 5 — Check Level and Height Offset From Level before drawing
Click OK twice to return to sketch mode, then read the Properties palette before you draw the first line.
| No. | Item | Meaning |
|---|---|---|
| 1 | Level and Height Offset From Level | The host level and the shift from it. This pair sets the slab elevation |
| 2 | The Structural tick | Already on, because the command was Floor: Structural |
The Dimensions group is still empty. Revit fills in Perimeter, Area and Volume only once the boundary closes.
Step 6 — Draw a closed boundary
The contextual tab of sketch mode carries four panels.
| Panel | Contents |
|---|---|
| Mode | The red cross discards the sketch, the green tick finishes it and builds the slab |
| Draw | Boundary Line, Slope Arrow, Span Direction, the shape tools, Pick Lines and Pick Walls |
| Set Offset | Extend Into Wall and an Offset box, for slab edges that run into the wall core |
| Work Plane | Sets and shows the work plane |
When the command starts, the status bar reads Pick walls to create lines. On a structural model it is usually easier to follow beam centrelines: pick the rectangle or line tool in the Draw panel and draw.
The boundary must close and must not cross itself. One slab can carry several loops: the outer loop is the slab edge, an inner loop becomes a hole. To abandon the sketch, click the red cross rather than relying on the Esc key.
Step 7 — Set the span direction of the slab
In the Draw panel, click Span Direction and then click the boundary edge the slab spans parallel to. That symbol is what Vietnamese structural drawings call the working direction of the slab.
The symbol changes no geometry, but it goes onto the sheet and tells the reader whether the slab is one-way or two-way. Autodesk documents the command on Specify the Span Direction of a Structural Floor, including the Align Perpendicular button that squares the symbol to a beam or a grid line.
Step 8 — Finish the sketch and read back three numbers
Click the green tick, select the new slab and read the Properties palette.
| No. | Item | Value on screen |
|---|---|---|
| 1 | Level and Height Offset From Level | 3F and −100.0, so the slab sits 100 mm below the level |
| 2 | The Structural tick | On, so the slab carries a structural role |
| 3 | Perimeter, Area, Volume | 8700.0 mm, 4.092 m² and 0.491 m³ |
Those last three are a quick sanity check: 4.092 times 0.12 is exactly 0.491. Scroll further and you find Elevation at Top 7400.0, Elevation at Bottom 7280.0 and Thickness 120.0.
Drops, slopes and floor openings in Revit
Step 9 — Drop one area of the slab
Several slab elevations inside one storey is normal, not a modelling mistake. Bathroom slabs drop to make room for waste pipes, balcony slabs drop so that water never runs back indoors.
The correct way is to split the area into several slabs, each with its own Height Offset From Level. On the sample plan the tags read S120 (+3.570), S120 (+3.800) and S120 (+3.850) — 280 mm between the lowest and the highest. The tag reads the parameter, so a correct model produces a correct drawing.
Step 10 — Slope a slab with a slope arrow
Ramps, stair landings and draining balconies are all built with a slope arrow. Inside sketch mode, click Slope Arrow and draw an arrow from one edge to the other. Select the arrow and Properties shows every control it has.
| No. | Item | Meaning |
|---|---|---|
| 1 | The Specify box | Offers exactly two values: Height at Tail and Slope |
| 2 | Four elevation boxes | Tail is the arrow root, Head is the arrow point; each end has a level and an offset |
| 3 | Slope and Length | Greyed out while Specify is Height at Tail, because Revit computes them |
Local drawing sets usually note falls as a percentage or a ratio. With that convention, switch Specify to Slope and type the value straight in.
Step 11 — Cut a small hole in the slab boundary
A hole that stays inside one slab needs no separate command. Select the slab, click Edit Boundary, draw a second closed loop inside the first and click the green tick — the inner loop becomes the hole.
That is the tidy route for pipe penetrations and small service ducts. The drawback is that the hole belongs to that one slab only.
Step 12 — Cut a multi-storey hole with Shaft
Stair wells, lift pits and service risers that run the full height of the building call for Shaft. On the Structure tab, the Opening panel carries five buttons: By Face, Shaft, Wall, Vertical and Dormer.
The Draw panel here offers two line kinds, unlike the floor sketch. Boundary Line is the real edge and decides the shape of the cut. Symbolic Line is only an annotation, usually the two diagonals on the plan, and cuts nothing.
| No. | Item | Meaning |
|---|---|---|
| 1 | Base Constraint and Base Offset | The bottom level of the hole and its shift. Use a base offset of a few tens of millimetres below |
| 2 | Top Constraint, Unconnected Height, Top Offset | When the top follows a level, Unconnected Height greys out and Revit computes it |
One shaft cuts every slab it passes through, so a single edit updates all the storeys.
Structural walls in Revit and elevator shaft walls
Step 13 — Use Wall: Structural for bearing walls
Revit has two Wall buttons on two different tabs. The one on the Architecture tab builds enclosing walls; the one on the Structure panel builds load-bearing walls.
Pick Wall: Structural, then scroll the Properties palette down to the Structural group.
| No. | Item | Value on screen |
|---|---|---|
| 1 | The Structural tick | Already on and greyed out while placing, because the command was Wall: Structural |
| 2 | Structural Usage | Bearing, also greyed out. This is where the load-bearing role is declared |
Three Rebar Cover rows sit underneath. That is the real difference between the two commands: structural walls in Revit host reinforcement, enclosing walls do not.
Step 14 — Constrain the base and top of an elevator shaft wall
The Constraints group of a wall is far longer than that of a column or a beam, because a wall is constrained at both ends.
| No. | Item | Value on screen and meaning |
|---|---|---|
| 1 | Location Line | Wall Centerline — the wall sits evenly on both sides of the line you draw |
| 2 | Base Constraint and Base Offset | 1F and 0.0, so the wall starts at level 1F |
| 3 | Top Constraint and Unconnected Height | Up to level: 2F and 3900.0; the height box greys out because the top follows a level |
A lift core is where those three parameters matter most. Elevator shaft walls run from the foundation to the roof, so set Base Constraint to the lowest level and Top Constraint to Up to level of the highest one. Levels keep changing while a project is documented; a wall tied to levels follows them, a wall given a loose height does not.
Step 15 — Check the result in a three-dimensional view
Open a three-dimensional view, select one slab and type IC to isolate that category temporarily. One glance shows which storey is missing a slab, where two slabs overlap and whether the stair opening really cuts through. Reset the view afterwards with Reset Temporary Hide/Isolate; the visibility commands are covered in hiding and showing elements in Revit.
When it does not work
| Symptom | Cause and fix |
|---|---|
| The green tick returns a boundary error | Two segments do not meet, or the loop crosses itself. Click Show in the error box to jump to the gap |
| Esc will not leave sketch mode | The cursor is over the ribbon. Click the red cross, then answer the Sketch Discarded box |
| Add Point changes nothing | No layer of the floor type has Variable ticked. Open Edit Assembly and switch it on |
| The slab exists but the plan does not show it | Hidden individually, switched off in Visibility/Graphics, or outside the View Range |
| A shaft leaves a thin skin at its base | The base of the hole matches the slab face. Use a negative Base Offset |
What people get wrong
| Common belief | What Revit 2027 actually does |
|---|---|
| Architectural and structural floors are different objects | Both are the Floor system family; only the Structural tick differs |
| To drop an area, drag the slab down | Split it into several slabs, each with its own Height Offset From Level |
| The span direction symbol is decoration | It carries the working direction of the slab straight onto the issued drawing |
| Cutting the boundary is always the quickest hole | Multi-storey holes belong to Shaft; one edit then updates every storey |
| Revit 2027 still has the Options Bar | Those controls now live on the contextual ribbon panel and in Properties |
Frequently asked questions
Why does a slab at level zero have a negative soffit?
Because Revit puts the top face on the level and lets the thickness hang below. That matches the drawing convention, where zero is the finished floor level.
Can an architectural floor be turned into a structural one?
Yes. Select the slab and tick Structural in the Properties palette. The geometry stays, only the role changes.
How do I model a storey with three slab elevations?
Draw three separate slabs on the same Level, each with its own Height Offset From Level.
Should a lift opening use Shaft or a hole in the boundary?
Use Shaft. It cuts every slab it passes through and needs one edit when the plan changes.
Related articles
- How to draw a floor in Revit — the same command from the architectural side
- Structural columns in Revit — the columns that carry beams and slabs
- Beams in Revit — the beam layout slab boundaries usually follow
- Typical floors in Revit — repeating one finished storey up the building
- What is Revit Structure — the entry point to this whole series