townhouse.arch

# A 5.5 x 11 m three-storey terrace house — one drawing per storey, from `level` blocks.
#
# A terrace house is the building type that only makes sense in section, and `level` is
# how a plan says so. Each block is an ordinary plan body and becomes its own page:
# `arch compile` writes townhouse.L1.svg, townhouse.L2.svg, townhouse.L3.svg, and
# `describe --json` grows a `levels[]`. Everything outside the blocks — `units`, `grid`,
# `paper`, `scale`, `dims auto` — is stated once and applies to every storey, because one
# building is issued on one sheet at one scale.
#
# THE STAIR IS ONE OBJECT WRITTEN THREE TIMES. Ids are unique WITHIN a level, so the same
# `id=st` on all three storeys is not a clash — it is the declaration that these are one
# shaft. That single fact is what makes the upper floors legal: they have no front door
# of their own, and `lint` still reads the first-floor landing as reached from outside,
# because `describe().vertical` connects it to the storey below. Change one storey's id
# and you get `W_STAIR_UNMATCHED` rather than a silently disconnected floor.
#
# `dir` is declared per storey and is not decoration: the flight runs along its footprint's
# LONG axis, and `dir up` is entered at that axis's larger-coordinate end. Here the long
# axis is y, so the ground-floor flight is entered from the back of the hall and climbs
# toward the street; the same footprint on the top floor carries `dir down`, entered at
# the opposite end. That is also what the nav grid reads — a stair obstructs circulation
# everywhere except its entry edge, which is why the flight stops 1.15 m short of the back
# wall. That strip is the only route from the front door to the kitchen, and one flight
# length further south it measured 350 mm of built depth — 300 on the nav grid, against a
# 700 minimum, so `lint` refused the plan with `W_PATH_TOO_NARROW`. Moving the flight is
# the fix, not widening a door: nothing on the route is a named element to widen.
#
# WHY THE PARTITIONS DON'T MOVE. The spine wall at x=3200, the wet-room wall at y=4600 and
# the cross wall at y=7000 stand on all three storeys in the same place, so the WC, the
# bathroom and the shower room sit one above the other on a single stack. That is not
# copy-paste: in a terrace the spine carries the floors and the drain fixes the wet rooms,
# so what a storey is free to change is only what its rooms are called and what is in them.
#
# Two door kinds earn their place rather than illustrate themselves. The ground-floor WC
# opens off a hall 1.75 m wide with a stair in it, so its leaf is a `pocket`: it takes no
# corridor and none of the 7.7 m2 cloakroom, and `slide left` drives the panel north into
# 2.65 m of blank spine wall (it needs 850 — its own 800 plus a jamb). The garden door is
# a `sliding` leaf, which is what a patio door actually is. A hinged one swinging in would
# cross the dining table; swung out it would sweep the paving — and the dimension chain a
# builder reads the back elevation from. No non-hinged leaf sweeps anything: `doorSwing()`
# returns null for every kind but `hinged`, so `W_SWING_OBSTRUCTED` cannot even apply to
# it. A `sliding` door is drawn as a BYPASS pair — two leaves on two tracks inside the
# reveal, so it needs no blank wall to park on at all — and `slide` only says which of the
# two is the fixed one: `right` is measured along the host wall's traversal, and the shell's
# south run is walked east to west, so the western leaf is fixed and the eastern one travels.
plan "Townhouse" {
  units mm
  # `grid 50`: the spine partition is 200 and the cross walls 100, so every `flush`
  # fixture lands on a ...50 or ...00 face — coordinates this grid can express exactly.
  grid 50
  paper A3 portrait
  scale 1:50
  north up
  dims auto all

  # Outer faces 5500 x 11000; 4900 clear between the party walls. A terrace is blind on
  # both flanks, so every window in the house is on the front or the back — which is the
  # single fact that shapes the plan: the deep middle of each floor takes the stair and the
  # wet room, and the two ends take the rooms people sit in.
  let W = 5200        # shell centerlines
  let D = 10700
  let T = 300         # exterior thickness
  let SPINE = 3200    # the loadbearing spine, front to mid-plan
  let WET   = 4600    # the wet-room wall — the same line on all three storeys
  let BACK  = 7000    # the cross wall in front of the back room

  level 1 "Ground floor" {
    wall id=shell   exterior  thickness T   { (0,0) (W,0) (W,D) (0,D) close }
    wall id=spine   partition thickness 200 { (SPINE,0) (SPINE,BACK) }
    wall id=w_wet   partition thickness 100 { (0,WET) (SPINE,WET) }
    wall id=w_back  partition thickness 100 { (0,BACK) (W,BACK) }

    room id=r_hall    at (SPINE,0)  size 2000x7000 label "Hall"           uses hall entry circulation
    room id=r_living  at (0,0)      size 3200x4600 label "Living"         uses living
    room id=r_wc      at (0,WET)    size 3200x2400 label "Cloakroom"      uses wc
    room id=r_kitchen at (0,BACK)   size 5200x3700 label "Kitchen/Dining" uses kitchen dining

    door id=d_front  at (4200,0) width 1000 wall shell hinge left swing into r_hall
    door id=d_living on spine at 2300 width 900 swing into r_living
    # The pocket. `slide left` runs the panel back toward the spine's first point,
    # (3200,0) — north, into solid wall — not south toward the corner 800 mm away.
    door id=d_wc pocket on spine at 5800 width 800 slide left
    # The patio slider: two bypass leaves in one 1.2 m reveal, nothing swept, nothing
    # parked on the wall. `slide right` is west here, so the western leaf is the fixed one.
    door id=d_back sliding at (4200,D) width 1200 wall shell slide right

    opening id=o_kitchen at (4200,BACK) width 1200 wall w_back

    window id=n_living  at (1600,0) width 1600 wall shell
    window id=s_kitchen at (1400,D)  width 1600 wall shell

    furniture media in r_living anchor top-left flush size 1200x400 label "Media"
    furniture sofa  in r_living anchor bottom    flush size 2000x850 label "Sofa"

    furniture wc    in r_wc anchor bottom-left  flush size 400x700
    furniture basin in r_wc anchor bottom-right flush size 600x450

    # The kitchen run rides the shell's WEST segment (index 3, walked from (0,10700)
    # northward), so `offset` is a distance along that segment and both the position and
    # the quarter-turn come from the wall; the footprints come from the catalogue.
    furniture kitchen_sink against wall shell segment 3 offset 1200 in r_kitchen
    furniture stove        against wall shell segment 3 offset 2100 in r_kitchen
    furniture fridge       against wall shell segment 3 offset 2900 in r_kitchen
    furniture table in r_kitchen centered size 1400x900 label "Table"

    stair id=st at (4150,2600) size 900x3200 dir up
  }

  level 2 "First floor" {
    wall id=shell  exterior  thickness T   { (0,0) (W,0) (W,D) (0,D) close }
    wall id=spine  partition thickness 200 { (SPINE,0) (SPINE,BACK) }
    wall id=w_wet  partition thickness 100 { (0,WET) (SPINE,WET) }
    wall id=w_back partition thickness 100 { (0,BACK) (W,BACK) }

    room id=r_landing at (SPINE,0)  size 2000x7000 label "Landing"   uses circulation hall
    room id=r_bed1    at (0,0)      size 3200x4600 label "Bedroom 1" uses bedroom
    room id=r_bath    at (0,WET)    size 3200x2400 label "Bathroom"  uses bath
    room id=r_bed2    at (0,BACK)   size 5200x3700 label "Bedroom 2" uses bedroom

    # No exterior door on this floor. The stair below carries the same id, so the access
    # graph reaches this landing through the shaft.
    door id=d_bed1 on spine  at 1800 width 800 swing into r_bed1
    door id=d_bath on spine  at 5200 width 800 swing into r_bath
    door id=d_bed2 on w_back at 4200 width 800 swing into r_bed2

    window id=n_bed1    at (1600,0) width 1600 wall shell
    window id=n_landing at (4200,0) width 1200 wall shell
    window id=s_bed2    at (2600,D)  width 1800 wall shell

    furniture bed      in r_bed1 anchor bottom-left  flush size 1400x2000 label "Double"
    furniture wardrobe in r_bed1 anchor bottom-right flush size 1200x600  label "Wardrobe"

    # The three pieces go round the three walls the door is not on, so the leaf opens onto
    # bare floor: bath under the back wall, WC beside it on the spine, basin by the window.
    furniture bathtub in r_bath anchor bottom-left  flush size 1700x700
    furniture wc      in r_bath anchor bottom-right flush size 400x700
    furniture basin   in r_bath anchor top-left     flush size 600x450

    furniture bed      in r_bed2 anchor bottom-left flush size 1500x2000 label "Double"
    furniture wardrobe in r_bed2 anchor top-left    flush size 1400x600  label "Wardrobe"
    furniture chest    at (4550,9200) size 500x1000 label "Chest" in r_bed2

    stair id=st at (4150,2600) size 900x3200 dir up
  }

  level 3 "Second floor" {
    wall id=shell  exterior  thickness T   { (0,0) (W,0) (W,D) (0,D) close }
    wall id=spine  partition thickness 200 { (SPINE,0) (SPINE,BACK) }
    wall id=w_wet  partition thickness 100 { (0,WET) (SPINE,WET) }
    wall id=w_back partition thickness 100 { (0,BACK) (W,BACK) }

    room id=r_landing at (SPINE,0)  size 2000x7000 label "Landing"      uses circulation hall
    room id=r_study   at (0,0)      size 3200x4600 label "Study"        uses office
    room id=r_bath    at (0,WET)    size 3200x2400 label "Shower room"  uses bath
    room id=r_master  at (0,BACK)   size 5200x3700 label "Main bedroom" uses bedroom

    door id=d_study  on spine  at 1800 width 800 swing into r_study
    door id=d_bath   on spine  at 5200 width 800 swing into r_bath
    door id=d_master on w_back at 4200 width 900 swing into r_master

    window id=n_study   at (1600,0) width 1600 wall shell
    window id=n_landing at (4200,0) width 1200 wall shell
    window id=s_master  at (2600,D)  width 1800 wall shell

    furniture desk     in r_study anchor top-left    flush size 1600x700 label "Desk"
    furniture bookcase in r_study anchor bottom-left flush size 1800x400 label "Bookcase"

    # The same three walls as the bathroom below, and a shower where the bath is — the
    # drain, the vent and the door all stay where the storey under them put them.
    furniture shower in r_bath anchor bottom-left  flush size 900x900
    furniture wc     in r_bath anchor bottom-right flush size 400x700
    furniture basin  in r_bath anchor top-left     flush size 600x450

    furniture bed      in r_master anchor bottom-left flush size 1600x2100 label "Double"
    furniture wardrobe in r_master anchor top-left    flush size 1800x600  label "Wardrobe"
    furniture chest    at (4550,8500) size 500x1000   label "Chest" in r_master

    stair id=st at (4150,2600) size 900x3200 dir down

    # The eaves, on the top storey only — `roof` is per-level like everything else
    # here, and this level's `shell` is the plan's one closed exterior ring on THIS
    # page, so no `wall` clause is needed.
    roof overhang 400
  }

  title {
    project "Three-storey Terrace"
    drawn_by "ArchLang"
    date "2026-08-16"
  }
}