Connect storeys (stairs, shafts, voids)
Write stairs, lift shafts and voids between spaces that stack. Do not write riser counts, treads or slopes — let the form be derived.
File paths in the output below are absolute when you actually run these commands. They are shortened to bare filenames here for readability.
The vertical default is a floor
Between two spaces whose plans overlap there is a floor, whether or not you write one. That is the default, so there is nothing to write for a floor. You write only the exceptions, and there are exactly three.
| Type | Passable | Floor | What it is for |
|---|---|---|---|
stair | yes (counts 0 doors) | none | stairs, ramps, escalators |
shaft | no | none | lift shafts, duct and pipe shafts |
void | no | none | double-height voids |
One word, stair, carries the whole topology of vertical passage. A stair, a ramp and an escalator are the same relation — you can get from one level to the next — and the difference between the devices is declared on the space, not on the boundary. The three types are set out in stack.
1. Put a space on each storey
A vertical relation is a relation between two spaces, so both ends have to exist. A stair needs a stair space on every storey it serves; a shaft needs a shaft space on every storey it passes.
space /L1..L3/st stair X2..X3 Y1..Y2 name:Stair use:common stair:N form:return
space /L1..L3/ev shaft X3..X4 Y1..Y2 name:Lift use:common lift:1A path whose head is a span, L1..L3, expands over the declared levels in z order. Write a typical floor once covers that notation.
Vertical circulation is space. It has area, it is passable, it carries escape. Reduce it to a connection and it drops out of the schedules.
2. Do not declare the form — choose the rule that generates it
Riser count, riser height, tread and slope appear nowhere in the source. You write where it is, how big it is and which way it climbs; the form follows from the level difference and the derived going.
| Attribute | Meaning |
|---|---|
stair:N/E/S/W | a stair, and the direction of climb (N=+Y, S=−Y, E=+X, W=−X) |
ramp:N/E/S/W | a ramp |
escalator:N/E/S/W | an escalator |
lift:1 | a lift (no going) |
form:return / form:straight | scissor/return flights, or one straight flight |
slope: | declares the maximum gradient; used by validation |
There is no spiral stair. A spiral is written as successive returns (form:return). The full list of attributes is in vertical circulation.
3. Write the vertical boundaries
For two storeys, one boundary is enough.
boundary /L1/hall /L2/hall type:stairFor many storeys, write it once with stack. stack <last path segment> <level range> type: is the same as writing one vertical boundary per consecutive pair of levels.
stack st L1..L3 type:stair
stack ev L1..L3 type:shaftstack ev L1..L3 type:shaft is exactly these two lines:
boundary /L1/ev /L2/ev type:shaft
boundary /L2/ev /L3/ev type:shaftA relation that spans storeys belongs to no storey's layer. Put it in the base layer when the building is split across files.
Check it
koyu 1.0
name Connecting storeys
unit mm
grid X 0 8400 11200 14000
grid Y 0 5600 8400
level L1 0 h:2800 slab:1400
level L2 4200 h:2800 slab:1400
level L3 8400 h:2800 slab:1400
level R 12600 slab:600
space /out exterior name:Outside
space /L1..L3/st stair X2..X3 Y1..Y2 name:Stair use:common stair:N form:return
space /L1..L3/ev shaft X3..X4 Y1..Y2 name:Lift use:common lift:1
space /L1..L3/hall hall X2..X4 Y2..Y3 name:Lift-lobby use:common
space /L1/lobby hall X1..X2 Y1..Y3 name:Entrance use:common
space /L2..L3/office room X1..X2 Y1..Y3 name:Tenancy use:exclusive
boundary /L1..L3/hall /L1..L3/st t:200 spec:RC
door w:900 name:Stair-fire-door
boundary /L1..L3/hall /L1..L3/ev t:200 spec:RC
boundary /L1..L3/st /L1..L3/ev t:200 spec:RC
boundary /L1/lobby /L1/st t:200 spec:RC
boundary /L1/lobby /L1/hall type:open
boundary /L1/lobby /out edge:W t:200 spec:CW
door w:1800 name:Front-entrance
boundary /L1/lobby /out edge:N t:200 spec:CW
boundary /L1/lobby /out edge:S t:200 spec:CW
boundary /L2..L3/office /L2..L3/st t:200 spec:RC
boundary /L2..L3/office /L2..L3/hall t:200 spec:RC
door w:1600 name:Tenancy-entrance
boundary /L2..L3/office /out edge:W t:200 spec:CW
boundary /L2..L3/office /out edge:N t:200 spec:CW
boundary /L2..L3/office /out edge:S t:200 spec:CW
boundary /L1..L3/st /out edge:S t:200 spec:RC
boundary /L1..L3/ev /out edge:S t:200 spec:RC
boundary /L1..L3/ev /out edge:E t:200 spec:RC
boundary /L1..L3/hall /out edge:N t:200 spec:RC
boundary /L1..L3/hall /out edge:E t:200 spec:RC
stack st L1..L3 type:stair
stack ev L1..L3 type:shaft$ npx tsx src/cli.ts check vert.muro
✔ Consistent — 13 spaces / 43 boundaries
Structural consistency only — architectural validity is what koyu validate says, separatelykoyu runs answers with the form you did not write. Neither the riser count nor the tread appears anywhere in the source.
$ npx tsx src/cli.ts runs vert.muro
L1→L2 lift Lift /L1/ev
L1→L2 stair Stair rise 4200mm return 24 risers of 175mm, tread 300mm going 6600mm /L1/st
L2→L3 lift Lift /L2/ev
L2→L3 stair Stair rise 4200mm return 24 risers of 175mm, tread 300mm going 6600mm /L2/st
L3→R lift Lift /L3/ev
L3→R stair Stair rise 4200mm return 24 risers of 175mm, tread 300mm going 6600mm /L3/stA stair is a passable edge that adds no doors. The four doors from the third-floor tenancy to the street are the tenancy entrance, the stair fire door on L3, the stair fire door on L1 and the front entrance — descending two storeys costs nothing.
$ npx tsx src/cli.ts doors vert.muro /L3/office /out
4 doors — /L3/office → /L3/hall → /L3/st → /L2/st → /L1/st → /L1/hall → /L1/lobby → /outA shaft is not a route. Continuous is not the same as passable.
$ npx tsx src/cli.ts doors vert.muro /L1/ev /L2/ev
Cannot reach /L2/ev from /L1/evWrite a void
Where the ceiling below is open, put a void space on the upper storey and write a type:void vertical boundary to the space below.
space /L2/void void X2..X3 Y1..Y2 name:Over-the-living-room
boundary /L1/ldk /L2/void type:voidA void carries no floor area, and koyu stats says so.
L2
/L2/bed Main-bedroom bedroom 26.50 m2
/L2/hall Upper-hall hall 13.25 m2
/L2/void Over-the-living-room void (not counted as floor area)
Subtotal 39.75 m2It is not passable either. The ↕ void line in koyu graph looks like an edge, but nobody crosses it.
/L2/void (Over-the-living-room)
↕ void → /L1/ldk
| wall → /L2/bed
| wall → /L2/hall$ npx tsx src/cli.ts doors two.muro /L1/ldk /L2/void
Cannot reach /L2/void from /L1/ldkWhere it goes wrong
The form is there but nothing connects — run.disconnected (caution)
Write stair: and form: but no stack and no vertical boundary, and the stair's form is derived while the circulation graph stays cut. check returns green. koyu validate is what catches it.
⚠ [run.disconnected] vert-nostack.muro:line 15: /L1/st has a vertical-circulation form but no vertical boundary connecting the levels (write stack or boundary type:stair — the form exists, but the graph cannot pass)
⚠ [run.disconnected] vert-nostack.muro:line 15: /L2/st has a vertical-circulation form but no vertical boundary connecting the levels (write stack or boundary type:stair — the form exists, but the graph cannot pass)
⚠ [run.disconnected] vert-nostack.muro:line 15: /L3/st has a vertical-circulation form but no vertical boundary connecting the levels (write stack or boundary type:stair — the form exists, but the graph cannot pass)The steps come out cramped — stair.proportion (caution)
Too short a stair enclosure crams the same risers into a shorter going, and the tread starves. Shrink the stair space above from 8400 deep to 4000:
$ npx tsx src/cli.ts runs vert-cramped.muro
L1→L2 lift Lift /L1/ev
L1→L2 stair Stair rise 4200mm return 24 risers of 175mm, tread 164mm going 3600mm /L1/st⚠ [stair.proportion] vert-cramped.muro:line 15: Derived step dimensions are cramped: 24 risers of 175mm, tread 164mm (2*riser+tread = 514mm; expected 550-700mm)What you fix is the size of the enclosure, not the size of the step. Choose dimensions before you write shows how to size the going from the storey height first.
Escaping through a shaft
Of all the reasons doors says "cannot reach", shaft and void are the hardest to spot. A lift shaft that runs the full height of the building is still not a route. Escape has to go through stair.
Next
- Find spaces you cannot reach — test the route you think you built
- Write a typical floor once — when the same core repeats
- Choose dimensions before you write — real sizes for stairs and shafts