The site — site.escape / site.area / site.frontage

rule	level
site.escape	violation
site.area	caution
site.frontage	violation

The site is the zone carrying site:1, and its shape is given by the polygon at the same path. The soundness of the shape itself — duplicate vertices, self-intersection, a polygon with no corresponding zone — is what koyu check says. Broken given data yields no shape at all, so that belongs to reading the source.

What this chapter holds are judgements about the relation between the building and the site.

Coverage and floor-area ratios are numbers, so koyu site returns them. Comparing them against a limit needs a fact that was never written — which zoning district this is — so there is no judgement for it.

site.escape — it escapes the site outline

violation

A space with a region lies outside the site polygon.

koyu 1.0
grid X 0 10000 14000
grid Y 0 10000
level L1 0 h:2400 slab:150
zone /site name:敷地 site:1
polygon /site 0,0 10000,0 10000,10000 0,10000
space /site/yard yard X1..X2 Y1..Y2 level:L1
space /L1/a room X2..X3 Y1..Y2

✖ [site.escape] main.muro:line 8: /L1/a escapes the site shape (near 14000,0)
Validation — 1 violation / 0 cautions

The polygon stops at X = 10000, while /L1/a occupies X2..X3 = 10000..14000.

The test is not just corner containment. It also looks for polygon vertices intruding into the space and for edges crossing, so it is correct on a concave site — a flag lot, or one with a cut corner. Sitting on the line counts as inside, with a 1mm tolerance.

What is compared is not the written layout but the derived region, so an outline cut to follow the site passes as written.

Two kinds of space are never counted: spaces under the site zone (/site/…) and type:exterior spaces. The landscape tiles and the roads are supposed to be out there.

The message prints the coordinates of the first escaping point found. One space yields at most one finding.

Fix — bring the layout inside the site, or correct the surveyed values in the polygon. Above, if the polygon is right, shrink the space; if the space is right, correct the vertices to 0,0 14000,0 14000,10000 0,10000.

site.area — the declared and derived site areas disagree

caution

The zone's area: (a transcription of the survey) and the area computed from the polygon differ by 0.05 m² or more.

koyu 1.0
grid X 0 10000
grid Y 0 10000
level L1 0 h:2400 slab:150
zone /site name:敷地 site:1 area:120.00
polygon /site 0,0 10000,0 10000,10000 0,10000
space /site/yard yard X1..X2 Y1..Y2 level:L1

⚠ [site.area] main.muro:line 5: Declared and derived site areas disagree: declared 120 m2 / derived 100.00 m2
Validation — 0 violations / 1 caution

A 10 m square polygon is 100 m², but area: says 120.00. One fact is written in two places, and the two disagree. Either a mistyped vertex, a transcription error in area:, or a survey update that reached only one of them.

A site with no area: is not checked. With only one number there is nothing to disagree with.

Fix — decide which is right and correct the other. Since area: is a transcription of the survey result, the thing to suspect is usually the polygon's vertices. koyu site prints both figures side by side.

koyu site main.muro

Site /site (敷地)
  Site shape: polygon with 4 vertices (a polygon declaration — given geometry)
  Site area: declared 120.00 m2 / derived 100.00 m2
  Building footprint (horizontal projection, rough): 100.00 m2 → building coverage ratio 83.3%
  Total floor area: 100.00 m2 → floor area ratio 83.3%

site.frontage — the road frontage is too short

violation

The boundary segments between an exterior space carrying road: (its width in mm) and the spaces under the site zone total less than 2000mm.

koyu 1.0
grid X 0 1500 10000
grid Y 0 10000 11000
level L1 0 h:2700 slab:150
zone /site name:敷地 site:1
polygon /site 0,0 10000,0 10000,10000 0,10000
space /site/yard yard X1..X3 Y1..Y2 level:L1
space /out/road-n exterior X1..X2 Y2..Y3 name:北側道路 road:4000 level:L1
boundary /site/yard /out/road-n type:open

✖ [site.frontage] main.muro:line 8: Road frontage is too short: /out/road-n — 1500mm (needs at least 2000mm)
Validation — 1 violation / 0 cautions

The road meets the site over X1..X2 = 0..1500 only. What is measured is the length of the boundary segments, not the road's own width (road:4000).

Only the boundary between the site and the road counts as frontage. A building wall facing the road does not — the only lengths summed are those on boundaries written between a road and a space under the site:1 zone (the landscape tiles).

With no site declared, the rule does not run. In a model with no site:1 zone the frontage derives as 0, but that is "not derivable", not "no frontage". Models that write a road and no site genuinely exist — a basement section, for instance. Draw a line under a number that could not be derived, and not writing something becomes a violation.

The 2 m floor is a rule on the architectural side. The frontage length itself is derived as a number, and koyu site lists it road by road.

Fix — write the boundary that faces the road. In the example, correct the width over which the site meets the road (X1..X2) to the real one.

koyu 1.0
grid X 0 4000 10000
grid Y 0 10000 11000
level L1 0 h:2700 slab:150
zone /site name:敷地 site:1
polygon /site 0,0 10000,0 10000,10000 0,10000
space /site/yard yard X1..X3 Y1..Y2 level:L1
space /out/road-n exterior X1..X2 Y2..Y3 name:北側道路 road:4000 level:L1
boundary /site/yard /out/road-n type:open

Site /site (敷地)
  Site shape: polygon with 4 vertices (a polygon declaration — given geometry)
  Site area (derived): 100.00 m2
  Road: /out/road-n (北側道路) width 4000mm / frontage 4000mm
  Building footprint (horizontal projection, rough): 0.00 m2 → building coverage ratio 0.0%
  Total floor area: 0.00 m2 → floor area ratio 0.0%

See also

• koyu site — site area, frontage, footprint, coverage and floor-area ratios as numbers
• The validation ledger — all fifteen rules, and why Finding is not Diagnostic