Vertical circulation — stair.proportion / run.slope / run.disconnected

rule	level
stair.proportion	caution
run.slope	caution
run.disconnected	caution

Riser counts, goings, landings and slopes are never written. You write the device and the direction of ascent (stair:N, ramp:E, escalator:S, lift:N); everything else falls out of the region and the storey height. koyu check guarantees that the declaration determines one shape — whether that shape can be climbed is what this volume says.

Because the stance is "write nothing, check everything", what is checked is not a written value. It is a derived one.

koyu runs main.muro

L1→L2	stair	s	rise 3000mm	straight	17 risers of 176mm, tread 150mm	going 2400mm	/L1/s

A lift has neither steps nor a pitch, so none of the rules in this chapter apply to one.

stair.proportion — the derived step is cramped

caution

The derived going is under 240mm, or 2×riser + going falls outside 550–700mm. The second is the pace rule.

koyu 1.0
grid X 0 3000
grid Y 0 4600
level L1 0 h:2700 slab:300
level L2 3000 h:2700 slab:300
space /L1/s stair X1..X2 Y1..Y2 stair:N
space /L2/s stair X1..X2 Y1..Y2
stack s L1..L2 type:stair

⚠ [stair.proportion] main.muro:line 6: Derived step dimensions are cramped: 17 risers of 176mm, tread 150mm (2*riser+tread = 502mm; expected 550-700mm)
Validation — 0 violations / 1 caution

The arithmetic runs like this. The rise is 3000mm and the riser ceiling defaults to 180mm, so there are 17 risers of 3000/17 = 176mm. The 4600mm depth along travel loses the boarding floor at each end (1100mm by default), leaving 2400mm of run, divided by 16 goings = 150mm. The stair shaft is too shallow.

riser: overrides the riser ceiling, entry: the boarding floor, landing: the intermediate landing.

In a return stair (form:return) each flight has its own going. The check reads the tightest flight, so the going reported is that flight's.

There are three fixes, and each of them changes an input to the derivation.

koyu 1.0
grid X 0 3000
grid Y 0 7000
level L1 0 h:2700 slab:300
level L2 3000 h:2700 slab:300
space /L1/s stair X1..X2 Y1..Y2 stair:N
space /L2/s stair X1..X2 Y1..Y2
stack s L1..L2 type:stair

✔ Nothing caught by validation (this is a judgement, not a guarantee about the composition)

Deepened along travel, 4600 → 7000mm. The run is 4800mm over 16 goings = 300mm, and 2×176 + 300 = 652mm lands inside the pace rule.

Left shallow, folding it with form:return doubles the run and reaches the same 300mm.

koyu 1.0
grid X 0 3000
grid Y 0 4600
level L1 0 h:2700 slab:300
level L2 3000 h:2700 slab:300
space /L1/s stair X1..X2 Y1..Y2 stair:N form:return
space /L2/s stair X1..X2 Y1..Y2
stack s L1..L2 type:stair

✔ Nothing caught by validation (this is a judgement, not a guarantee about the composition)

The third is to raise riser: and use fewer steps. This is a dimensional warning, not a code-compliance verdict.

run.slope — the derived slope leaves the band

caution

It means different things for a ramp and for an escalator. They share a rule name because they are one fact: the derived slope has left the band that would be accepted.

A ramp — steeper than the limit you declared

slope: is not the slope. It is the limit you will accept, and it exists only so this check can be made. slope:12 means "no steeper than 1/12".

koyu 1.0
grid X 0 3000
grid Y 0 6000
level L1 0 h:2700 slab:300
level L2 3000 h:2700 slab:300
space /L1/r ramp X1..X2 Y1..Y2 ramp:N slope:12
space /L2/r ramp X1..X2 Y1..Y2
stack r L1..L2 type:stair

⚠ [run.slope] main.muro:line 6: Derived slope 1/1.3 is steeper than the declared 1/12 (lengthen the run or lower the storey height)
Validation — 0 violations / 1 caution

Against a 3000mm rise there is only 3800mm of run (6000mm less the 1100mm boarding floor at each end), giving 1/1.3 — an order of magnitude off the 1/12 asked for.

A ramp with no slope: is not checked. koyu does not invent a limit for a ramp that declared none.

Fix — lengthen the ramp along travel, fold it with form:return to double the run, or lower the storey height. Actually achieving 1/12 in the example above takes 40000mm along travel (a 37800mm run, giving 1/12.6). Ramps are long. The numbers say so.

An escalator — outside the usual band

An escalator needs no slope:. If the derived pitch falls outside 1/2.3 – 1/1.4 — a band around the usual 1/1.7, i.e. 30° — the same rule fires.

koyu 1.0
grid X 0 1200
grid Y 0 12000
level L1 0 h:2700 slab:300
level L2 3000 h:2700 slab:300
space /L1/e room X1..X2 Y1..Y2 escalator:N
space /L2/e room X1..X2 Y1..Y2
stack e L1..L2 type:stair

⚠ [run.slope] main.muro:line 6: Derived slope 1/3.3 is outside the usual escalator range (about 1/1.7 = 30 degrees)
Validation — 0 violations / 1 caution

This is the too shallow side. The region is so long that the derivation produced a reclining escalator nobody builds. Shorten the same region to 7200mm and the run is 5000mm, the pitch 1/1.7, and the judgement passes.

run.disconnected — no vertical boundary joins the levels

caution

Shape and topology are written separately. stair:N builds treads; it does not claim that the two levels are connected. What connects them is a stack, or a boundary type:stair.

koyu 1.0
grid X 0 3000
grid Y 0 7000
level L1 0 h:2700 slab:300
level L2 3000 h:2700 slab:300
space /L1/s stair X1..X2 Y1..Y2 stair:N
space /L2/s stair X1..X2 Y1..Y2

⚠ [run.disconnected] main.muro:line 6: /L1/s 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)
Validation — 0 violations / 1 caution

Without a vertical boundary, koyu doors will not find a route upstairs. A stair that is drawn but not walkable is the hardest mismatch to notice, which is why it warns.

The test is blunt: it asks whether the space is an endpoint of some type:stair or type:shaft boundary, and does not ask whether it connects to the right level.

Fix — write stack s L1..L2 type:stair. Conversely, if you want the connection without a generated shape (a lift shaft, say), drop the vertical-circulation attribute and keep the vertical boundary.

See also

• koyu runs — device, rise, riser count, going, slope and run length in one list
• Reachability — whether a run is stranded off the customer's route is what access.backofhouse says
• The validation ledger — all fifteen rules, and why Finding is not Diagnostic