This is the staircase half of the floor plan symbols guide. Each symbol is drawn twice — the convention, and the same stair on a Gridsnap plan — and the difference here is worth knowing up front: Gridsnap writes no UP. It marks the bottom step with a small circle and the top with an arrowhead, so the direction is read from the walk line itself.
The parts of a stair symbol
| Part | What it is |
|---|---|
| Treads | The parallel lines. One line per step, drawn at the real going, so counting them tells you the number of steps. |
| Walk line | The line down the middle of the flight, following the route you actually walk. On a turn it stays a constant distance from the inside edge. |
| Arrow | The end of the walk line, pointing the way the flight rises. |
| UP / DN | Read from the floor whose plan you are on. The same stair is UP downstairs and DN upstairs. |
| Break line | The diagonal double slash where the cut plane passes through the flight. Everything past it belongs to the storey above. |
| Landing | A blank rectangle between two runs of treads — no lines, because it is one level surface. |
Stair symbols, drawn twice
Straight flight
Also called: straight run, single flight
A row of parallel lines, one per tread, with a walk line running the direction of travel — the arrow and the UP label point away from the floor you are standing on.
Gridsnap writes no UP. It marks the bottom step with a small circle and the top with an open arrowhead, so the direction is read from the walk line itself — which is the same information, and survives being rotated or mirrored without the label ending up upside down.
Break line
Also called: cut line, the diagonal slash
The diagonal double slash across a flight marks where the cut plane passes through it: the treads below are drawn solid, everything above is not this floor's business.
Gridsnap draws no break line: it draws the whole flight, and the storey above shows the stair below it as a dashed ghost instead. The information a break line carries — "this continues past the cut" — is carried by the stairwell opening the stair cuts in the slab above it, automatically.
L-shaped stair
Also called: quarter-turn, dog-leg with a landing
Two flights at right angles with a square landing in the corner, drawn as two runs of treads and one blank square.
Gridsnap has both hands as separate shapes — L-left and L-right — so which way the stair turns is a property of the stair, not something you achieve by mirroring the drawing.
U-shaped stair
Also called: half-turn, switchback, dog-leg
Two parallel flights running opposite ways with a landing across the top: the compact stair, because it turns the whole rise back on itself.
The gap between the two flights is a setting, so the stair can be drawn tight against itself or opened up around a stairwell. A U stair's width in Gridsnap is the width of ONE flight, not the footprint.
Winder turn
Also called: winders, kite steps
Tapered treads fanning around the turn instead of a flat landing, so the stair keeps rising through the corner — the same storey height in a shorter footprint.
A U-shaped stair in Gridsnap turns either on a landing or on winders. Winders need the two flights side by side to let the fan reach the newel, so the flight gap is ignored while they are on.
Spiral stair
Also called: helical, circular stair
Treads radiating from a central newel, drawn as a circle cut into wedges with the walk line spiralling out from the middle.
Gridsnap draws straight, L-shaped and U-shaped stairs. There is no spiral, and no honest way to fake one — a circle of furniture would not cut the stairwell in the floor above or show as a stair in 3D. Draw the opening it needs and note the stair on the plan.
UP, DN, and the same stair on two plans
A staircase appears on two floor plans, and it looks different on each — which is the single thing that confuses people most about stair drawings. On the lower floor it is drawn from the bottom step up to the break line, labelled UP. On the upper floor it is drawn from the break line to the top step, labelled DN, and around it is the stairwell — the hole in the floor that the stair comes up through.
That hole is not optional and it is not small. It has to be long enough that anyone on the flight has 2000 mm of headroom above their head all the way up, which in practice means the opening runs back over several treads. It is the most commonly forgotten thing on a first-time plan: the stair is drawn, the floor above is drawn, and nothing has been taken out of it.
In Gridsnap the stairwell is cut for you — the stair on one floor punches the opening in the slab of the floor above it — and the flight below shows through as a dashed ghost so you can see what you are standing over. There is no break line to draw, because there is nothing to break: the model knows where the stair really is.
The numbers behind the symbol
A stair symbol is only honest if the steps under it are real, and four numbers decide that:
- Riser 170–190 mm, going 250–280 mm for a home. Every riser in a flight must be identical — a single odd step is a trip hazard, which is why a parametric stair divides the height equally rather than letting you place steps by hand.
- 2R + G between 600 and 650 mm — the comfort rule. Two risers plus one going is roughly a pace, and a stair outside that range feels wrong to walk long before anyone measures it.
- 900 mm clear flight width for a house; wider if it is the main stair and furniture has to come up it.
- 2000 mm headroom over the whole flight — the number that sizes the stairwell above.
At a typical 3000 mm floor-to-floor, aiming at a 175 mm riser gives 17 risers of 176 mm and 16 treads. At a 270 mm going that is a 4.32 m run before the landing — which is usually the moment a straight flight becomes an L or a U. The stair calculator does that arithmetic, and the clearances cheat sheet has the rest of the numbers.
Drawing stair symbols yourself
Drawn by hand, a staircase is the most tedious symbol on the sheet: every tread has to be spaced equally, the walk line has to follow the turn, and changing the storey height means redrawing all of it. In Gridsnap a staircase is parametric — pick straight, L-shaped or U-shaped, set the width, length and number of steps, and the treads, walk line, arrow, 3D flight and stairwell opening all follow. Change the floor height and the steps re-divide themselves.
Next: door symbols and window symbols, or back to the full symbols reference. For riser, going, newel and the rest of the vocabulary, see the architect's glossary.
Staircase symbol questions
What does a staircase look like on a floor plan?
A run of parallel lines, one per tread, inside the outline of the flight, with a walk line down the middle showing the direction of travel. The walk line carries an arrow, and the flight is normally labelled UP or DN from the floor you are looking at.
What does the diagonal line across a staircase mean?
It is a break line. It marks where the plan's cut plane passes through the flight: treads below the break are on this floor, and everything past it continues up out of the drawing. On the storey above, the same stair appears with its lower part broken off and labelled DN.
Does UP mean up from this floor?
Yes. UP and DN are always read from the floor whose plan you are looking at. The same staircase is labelled UP on the lower floor's plan and DN on the upper floor's, and the arrow points the same way as the word.
How are L-shaped and U-shaped stairs drawn?
As two runs of treads with a blank square between them — the landing. An L-shaped stair turns 90 degrees, so its landing sits in the corner; a U-shaped stair turns back on itself, so the landing runs across the top of both flights. If the turn is made on tapered treads instead of a flat landing, they are winders.
What is the opening in the floor above a staircase called?
The stairwell, or the stair opening. It has to be long enough to give 2000 mm of headroom over the whole flight, which is usually what decides how long a staircase has to be. Gridsnap cuts it in the slab above automatically from the stair itself.
How many steps should a staircase have on a plan?
The floor-to-floor height divided by the riser. At a typical 3000 mm floor-to-floor, aiming at a 175 mm riser gives 17 risers of 176 mm, and the flight is 16 treads long plus the landing. Risers must all be equal — an odd one at the top or bottom is a trip.