Press S — or click the stairs icon in the toolbar — pick a shape, then click to place the staircase. Everything else is edited afterwards in the properties panel on the right: shape, flight width, length, total steps and rotation. Stairs are free and need no account.
Most stairs need nothing beyond those fields. Everything per-flight — individual step counts, individual run lengths, winders, a third flight — is folded away behind Customize flights, and you can ignore it entirely.
The four shapes
Select a staircase and the Shape dropdown offers:
| Shape | What it is |
|---|---|
| Straight | One flight, no turn. |
| L (turn left) | Two flights meeting at a quarter-turn, turning left as you climb. |
| L (turn right) | The same, turning right. |
| U (switchback) | Two parallel flights doubling back on each other — or three, with the middle one crossing the gap. |
Changing the shape keeps the position, the width and the total, so it is worth trying all four against the space you have. Swapping L-left for L-right is a mirror: your per-flight counts and run lengths survive it untouched.
Steps are RISERS
Steps (risers) is the number of times you step up. A riser is one step up; a flat landing stays flat and adds none of its own; the upper floor is the final landing. So a stair of 16 risers over 2800 mm has a 175 mm riser, whether it is straight, L-shaped or a U.
That has one visible consequence worth knowing: a flight that ends at a landing or at the upper floor draws one fewer tread than it has risers, because its last rise lands you on the landing (or on the floor) rather than on a tread of its own. A straight stair of 16 risers is 15 drawn treads. A flight that runs straight into a set of winders keeps all of its treads, because the first winder supplies that rise.
Stairs drawn before 15 September 2026 count differently: their number is walk slots — treads and landings alike, each one rising. The panel labels them Steps (walk slots) so the difference is on screen, and nothing about such a stair changes by opening, moving, rotating or saving it. Open Customize flights to see a preview of what converting it to per-flight control would change, with Apply and Cancel; Apply is one undo step.
The measurements
| Field | Range | Note |
|---|---|---|
| Flight width | 600–3000 mm | The width of one flight, for every shape. |
| Flight gap | U only | The clear gap between the two outer flights. |
| Length | — | The footprint along the walking direction. Becomes a computed read-only value once you set per-flight run lengths. |
| Steps (risers) | 3–100 | One riser minimum per flight, plus the winders. |
| Rotation | any | Steps by 15°, with a Rotate 90° button under it. |
Flight width being per-flight matters most on a U: the footprint across is two flight widths plus the Flight gap, so a 900 mm U with no gap is 1800 mm wide overall.
Under the fields, a summary line says what the stair actually measures —
16 risers × 175 mm · going 240 mm — and it updates on every edit, including
the height of each landing, so adding a step somewhere cannot move a landing
without you seeing it.
Customize flights
Open the disclosure and each segment gets its own row, numbered in walking order and linked to the little preview above: hover a row and its flight, landing or turn lights up both in the preview and on the plan.
| Segment | What you can edit | What it tells you |
|---|---|---|
| Flight 1 / 2 / 3 | Risers, horizontal run | Tread count, going, pitch |
| Landing A / B | — | Size, and its height above the departure floor |
| Turn, or First / Second corner | Number of winders | The spacing along the centre walking arc |
| Steps across gap | Number of treads | Going, pitch |
A flight can be as short as one riser, which is how you draw a single step up onto a landing, a platform or into a turn:
- one riser before winders is one tread, then the fan starts;
- one riser before a landing or the upper floor is no tread at all —
you step up once and you are on it, so that flight has no depth in plan
and its Run shows a derived
0. Give it another riser and its run comes back.
The one exception is the three-flight U’s middle flight: its run is the gap, so it needs at least one tread to cross it and cannot go below two risers.
Distribution starts as Auto: you set the total and Gridsnap shares the steps out in proportion to how far each flight has to travel. Editing any one flight’s risers switches it to Custom — from then on that count is yours, the other flights keep theirs, and the total is the read-only sum. Auto-distribute keeps your total and hands the sharing back.
Two more actions sit at the bottom: Equal outer runs copies the first outer run onto the other, and Reset customization drops the per-flight counts and run lengths while keeping the shape, turn, total, width, gap, destination and construction.
A three-flight U
A U has a Layout dropdown: Two flights (one landing) or Three flights (two landings). The three-flight version splits the turn band into a landing, a rising flight straight across the gap, and a second landing — the two landings sit at different heights, which is the whole point of it.
The middle flight needs somewhere to run, so the gap is its horizontal run. With no gap yet, the panel offers a single explicit action — Set 600 mm gap and use three flights — rather than quietly resizing your stair. Changing a three-flight U’s gap edits the middle run and nothing else; setting the gap to zero is not a way to delete the flight (switch back to two flights for that).
A three-flight U has two flat landings and no winder option.
Winders, on an L or a U
Turn offers Landing or Winders (no landing) on both L shapes and on a two-flight U. Winders are tapered treads fanning around the newel, so the stair rises continuously through the turn: the same storey height in a shorter footprint.
- An L’s quarter-turn takes 2–6 winders, 3 by default.
- A U’s half-turn takes 3–12, 6 by default. A U drawn before this release keeps the three it has.
- The winder count is yours: if the total is too small to carry it, Gridsnap tells you the minimum rather than quietly using fewer winders.
A U that turns on winders AND has a flight gap
With no gap, the two flights touch and the turn is one half-turn fan reaching the newel between them.
Give the Flight gap a value and the turn is made differently: a quarter-turn fan, then rising treads straight across the gap, then a second quarter-turn fan. Every part of it climbs — there is no flat landing anywhere — so you get a continuous rise and an open well, without switching to three flights.
Because that changes how the turn is built, the gap is previewed before it is applied: type a value and the panel shows what you would get — the two corner counts, the treads across the gap and their going, the new width and the new total — with Apply and Cancel. Nothing changes until you apply, and Apply is one undo step.
- The corners take 2–6 winders each, seeded by splitting the count you already had (a turn of 3 becomes two corners of 2, and the preview says so rather than making a one-step corner).
- Steps across gap is the number of rectangular treads crossing it. Their going is the gap divided by that count, and it is shown next to the row.
- The middle run is the gap, so it is a read-only value in the Flights section — there is never a second dimension for it.
- Setting the gap back to zero is previewed the same way: the two corners combine into one half turn and the treads across the gap go.
- A U saved with a gap that was being ignored keeps the staircase it was drawn with until you apply the change yourself.
What the fan is, and is not
The rays split the turn into equal angles, so the spacing along the centre walking arc is constant, and that is the number the panel reports — as a chord along that arc, which is what it measures. It is not a claim about the going at every position a building code measures one at.
The inner ends of these treads come to a point at the newel. That is a schematic turn, not a buildable balanced winder, and the plan check says so: Winder treads come to a point — on every fan, including the U winders drawn before this release. Balanced winders with real narrow-end dimensions are not built yet.
Gridsnap does not check any stair against a building code, and nothing it draws is approved.
Mirrored flips a U about its walking axis — the fix when the turn goes the wrong way for the room it stands in.
Where the flight lands
The panel’s From / To / Rise rows say what the stair connects:
| Row | What it says |
|---|---|
| From | The floor under the stair, worked out for you — including a split level, since a staircase stands on whichever slab is underneath it. |
| To | Where the flight arrives: the nearest storey above (the default), a floor you drew for a loft or a landing, or a Height for a flight to something not built yet. |
| Rise | The total rise, and the risers × the riser height it works out at. |
Change To and the riser and the pitch follow; the per-flight counts do not move. With nothing above it to arrive on, the stair is drawn on placeholder 175 mm risers, every measurement in the panel is marked an estimate, and the plan check says A stair has no floor to arrive on.
The well is cut for you
A stair with a destination cuts its own outline through every floor and ceiling between where it leaves and where it arrives. Nothing to draw, and nothing to keep in step when you move the stair. The Opening row controls it:
- Pin freezes the list of what it cuts to what it is now.
- Detach turns the hole into a floor opening of its own, on the storey the flight arrives at, which you can then reshape by hand.
- None cuts nothing. Cut the well again puts it back.
Guarding round the well draws a balustrade round the opening on the arrival storey, open on the side you step over — see guarding.
On a U with two different outer run lengths the well takes a notch where the shorter flight stops, rather than cutting a hole over floor that is still there.
On the upper floor the stair is drawn as a dashed ghost, which is how you see what you are landing onto while you draw around it.
How the flight is built
Construction changes what is built, not what is drawn. The plan symbol, the walk line and the rise are identical under all three, so this is a 3D and section decision:
| Construction | What stands there |
|---|---|
| Open (treads only) | Treads with nothing between them. What every plan drawn before this has. |
| Closed (with risers) | Each tread carried down to the one below. |
| Solid (cast flight) | A raked waist under the steps, one per straight run, with the soffit parallel to the nosings. |
Each straight run gets its own rake, so a three-flight U with three different goings is built with three different slopes, and each landing plate is as deep as the steeper of the two flights it joins. The first flight bears on the floor it leaves; the ones above spring off their landing.
Stringers, nosings and a balustrade along the flight are not modelled — a handrail beside the steps is a guarding run you draw.
What this doesn’t do
- No spiral or curved stairs. The four shapes above are the whole set.
- No balanced winders. See the warning above.
- One width for the whole stair. Individual flight widths, and a landing deeper than the flight width, are not editable.
- All risers are equal. The riser height follows from the rise between From and To and the total; you cannot set a landing’s height directly.
- No zero-riser flight. A flight is at least one step.
- Winders only on an L or a two-flight U. A three-flight U’s two corners are flat landings. A two-flight U with a gap turns on two quarter fans.
- Nothing is resized to cure a warning. Gridsnap reports; you decide.
Headroom and clashes
Two more free findings watch the flight as you draw. Headroom over a stair compares the clear height over every tread, landing and winder with the Stair headroom setting in the ⚙ dialog (2000 mm unless you change it, 1500–3000 mm). A stair runs into a floor or a ceiling reports a flight left inside construction it has no opening through. Both are reported, never repaired.
Next
Check the stair has room to be used: corridor and circulation widths covers the clear widths a stair and its landing need, and the plan check flags a stair it cannot reach.