Floors, roofs and stairs

Each element comes in two parts: a type that says how it is built, and the element that places it. Wire the stair’s void into the slabs and its edges into the balustrades, and the floor opens up where the stair comes through.

slab_types ─> slabs        roof_types ─> roofs
stair_types ─> stairs ─┬─> stairs.voids ─> slabs.openings
                        └─> stairs.edges ─> balustrades.path   (balustrade_types ─> balustrades)

NCC checks are first-pass design checks. They help you catch problems early. They are not certification.

Component	What it’s for
Slab types (next beta)	A floor build-up: concrete, post-tensioned, hollowcore, CLT, timber joists, waffle, steel deck, or your own layers, with a finish on top and a soffit below.
Slabs (next beta)	Layered slabs at the levels you choose, from closed outlines, with edge offsets, setdowns and openings cut for stair voids and shafts.
Roof types (next beta)	A roof build-up (metal deck, tiles, slate, membrane, green roof, or your own layers) with the pitches the covering allows.
Roofs (next beta)	Hip, gable, dutch gable, skillion or flat roofs over any simple outline, with eaves and verges, fascias and gutters, and a roof plan with fall arrows.
Stair types (next beta)	How a stair is built (in-situ or precast concrete, steel stringers, timber), with riser and going targets and the NCC limits for its use.
Stairs (next beta)	Straight, L, U or spiral stairs fitted between two levels, with first-pass NCC checks, a plan symbol, balustrade edges and the void for the floor above.
Balustrade types (next beta)	Frameless glass, glass and posts, bars, rails, wires, sheet or timber, with heights, post spacing, gaps and a handrail, checked against the NCC barrier rules.
Balustrades (next beta)	Balustrades along slab edges, stair edges or any curve, following a stair’s pitch, with plan and elevation linework and first-pass NCC checks.

Slab types

slab_types

New since 0.02-alpha: arrives in the next beta.

A floor build-up: concrete, post-tensioned, hollowcore, CLT, timber joists, waffle, steel deck, or your own layers, with a finish on top and a soffit below. Cost: Free.

Inputs

Input	Type	On the component	Default	What it does
`preset`	Text	Dropdown	`concrete 200`	a common floor build-up, or custom (from layers). One of `concrete 200`, `post-tensioned 250`, `hollowcore 200 + topping`, `CLT 180 + screed`, `timber joist floor`, `waffle 300`, `steel deck composite 150`, `slab on ground 100`, `custom`
`name`	Text	Text field	blank	type name (blank: from the preset, finish and soffit)
`layers`	list of Text	Text field	blank	layers top -> bottom, thickness in mm: ‘screed 50; CLT 180; plasterboard ceiling 13’ ( = structure). Replaces the preset’s layers when given
`finish`	Text	Dropdown	`none`	floor finish laid on top. One of `none`, `polished concrete`, `tiles`, `timber boards`, `carpet`, `vinyl`, `screed`, `raised floor`
`soffit`	Text	Dropdown	`as built`	underside: as built keeps the build-up’s own; the others replace its ceiling. One of `as built`, `exposed`, `plasterboard`, `suspended ceiling`, `render`, `acoustic panels`
`plane`	Plane	Wire	—	where the swatch sits (default: world origin)
`save`	Boolean	Button	—	add this type to the Alien library

Outputs

Output	Type	What it gives you
`slab_type`	Text	slab_type record for slabs
`names`	list of Text	layer names, top first
`materials`	list of Text	layer materials
`thicknesses`	list of Number	layer thicknesses (m)
`total`	Number	overall thickness (m)
`swatch`	list of Brep	a stepped sample, one solid per layer
`colours`	list of Colour	colour per swatch solid
`info`	Text	what happened: a summary, sources and notes

How it works

Presets: concrete 200, post-tensioned 250, hollowcore 200 + topping, CLT 180 + screed, timber joist floor, waffle 300, steel deck composite 150, slab on ground 100, custom.
Layers ‘screed 50; CLT 180*; plasterboard ceiling 13’ (mm, cm and m work; * = structure) replace the preset’s.
Save adds the type to the library (kind slab_type).

Slabs

slabs

New since 0.02-alpha: arrives in the next beta.

Layered slabs at the levels you choose, from closed outlines, with edge offsets, setdowns and openings cut for stair voids and shafts. Cost: Free.

Inputs

Input	Type	On the component	Default	What it does
`outline`	list of Curve	Select in Rhino	—	slab outlines, closed (a 10 x 7 m sample room when unwired); outlines at several heights each go to the level at their height
`levels`	list of Data	Wire	—	level records (sample levels when unwired)
`which`	Text	Text field	`floors`	levels to slab: floors (all but the top level, which is the roof’s), all, suspended (not the lowest or top), indices from 0 = lowest (‘1-3’), names or codes (‘L01, Level 2’)
`slab_type`	list of Data	Wire	—	slab_types record(s), one per chosen level from the lowest (the last repeats; default: concrete 200)
`offset`	Number	Slider -2–5	`0`	edge offset from the outline (m): + outward (e.g. to the outer face of the walls), - inward
`openings`	list of Curve	Select in Rhino	—	holes, closed curves: stair voids (stairs.voids), shafts, atria; ones crossing the edge cut notches
`through`	Text	Dropdown	`auto`	which slabs an opening cuts: its level = the level at the curve’s height; auto = that, unless it lies at the outline’s height (a sketch: then every slab). One of `auto`, `every level`, `its level`
`setdown`	Number	Slider 0–1	`0`	top of slab below the level (m), e.g. 0.05 for a wet area
`site`	Data	Wire	—	site record (optional): places the sample outline

Outputs

Output	Type	What it gives you
`slabs`	list of Text	slab records
`solids`	list of Brep	one solid per layer per slab
`materials`	list of Text	material per solid
`colours`	list of Colour	colour per solid
`edges`	list of Curve	slab edges at the top: outer edges and void edges (for balustrades)
`plan`	list of Curve	plan linework at the top: slab edges and a cross in each void
`area`	list of Number	net area of each slab (m2)
`info`	Text	what happened: a summary, sources and notes

How it works

which: floors (all but the top level, the roof’s) | all | suspended | indices ‘1-3’ | names or codes.
Edge offset, setdown, one slab type per chosen level (the last repeats); outlines at several heights go to their own level.
Openings cut at their own level (stair voids) or through every slab when sketched at the outline’s height (through = auto); overlapping openings merge, crossing ones notch.
edges output (outer and void edges at the top) feeds balustrades; area is net m2.

Roof types

roof_types

New since 0.02-alpha: arrives in the next beta.

A roof build-up (metal deck, tiles, slate, membrane, green roof, or your own layers) with the pitches the covering allows. Cost: Free.

Inputs

Input	Type	On the component	Default	What it does
`preset`	Text	Dropdown	`metal deck`	a common roof build-up, or custom (from layers). One of `metal deck`, `metal deck low pitch`, `concrete tile`, `terracotta tile`, `slate`, `membrane on concrete`, `green roof`, `custom`
`name`	Text	Text field	blank	type name (blank: the preset’s)
`layers`	list of Text	Text field	blank	layers top -> bottom, thickness in mm: ‘metal roofing 20; battens 40; insulation 55; rafters 140’ ( = structure). Replaces the preset’s layers when given
`colour`	Text	Dropdown	`as built`	colour of the roofing (the top layer). One of `as built`, `charcoal`, `dark grey`, `mid grey`, `light grey`, `off-white`, `red`, `terracotta`, `green`, `blue`
`plane`	Plane	Wire	—	where the swatch sits (default: world origin)
`save`	Boolean	Button	—	add this type to the Alien library

Outputs

Output	Type	What it gives you
`roof_type`	Text	roof_type record for roofs
`names`	list of Text	layer names, top first
`materials`	list of Text	layer materials
`thicknesses`	list of Number	layer thicknesses (m)
`total`	Number	overall thickness, square to the roof (m)
`swatch`	list of Brep	a stepped sample, one solid per layer
`colours`	list of Colour	colour per swatch solid
`info`	Text	what happened: a summary, sources and notes

How it works

Presets: metal deck, metal deck low pitch, concrete tile, terracotta tile, slate, membrane on concrete, green roof, custom.
roofs warns when the pitch is outside the covering’s range.
Save adds the type to the library (kind roof_type).

Roofs

roofs

New since 0.02-alpha: arrives in the next beta.

Hip, gable, dutch gable, skillion or flat roofs over any simple outline, with eaves and verges, fascias and gutters, and a roof plan with fall arrows. Cost: Free.

Inputs

Input	Type	On the component	Default	What it does
`outline`	list of Curve	Select in Rhino	—	wall lines to roof over, closed, one roof each (a 10 x 7 m sample room when unwired)
`levels`	list of Data	Wire	—	level records (sample levels when unwired)
`level`	Text	Text field	blank	level the roof sits on (the top of the walls): name, code or index (blank: the top level)
`form`	Text	Dropdown	`hip`	roof form. One of `hip`, `gable`, `dutch gable`, `skillion`, `flat`
`pitch`	Number	Slider 0–75	`22.5`	pitch (degrees); flat roofs: the fall written on the plan (5 or less)
`overhang`	Number	Slider 0–3	`0.6`	eaves overhang past the wall line (m)
`gable_overhang`	Number	Slider 0–3	`0.3`	verge overhang at gable ends and skillion sides (m)
`ridge`	Text	Dropdown	`auto`	ridge direction for gable, dutch gable, skillion and flat: auto = along the long side; skillion and flat fall across it. One of `auto`, `x`, `y`
`flip`	Boolean	Switch	off	skillion and flat: fall the other way
`fascia`	Number	Slider 0–0.6	`0.2`	fascia and barge board depth (m), with gutters on the eaves; 0 = none
`roof_type`	Data	Wire	—	roof_types record (default: metal deck)
`site`	Data	Wire	—	site record (optional): x/y and placement, north for face aspects, scale for plan text

Outputs

Output	Type	What it gives you
`roofs`	list of Text	roof records
`solids`	list of Brep	one solid per layer per roof part, then fascias, barge boards, gutters and gablets
`materials`	list of Text	material per solid
`colours`	list of Colour	colour per solid
`ridges`	list of Curve	ridge lines (and a skillion’s high edge)
`hips`	list of Curve	hip lines
`valleys`	list of Curve	valley lines
`eaves`	list of Curve	roof edges: eaves, verges (gable rakes) and gablet bases
`plan`	list of Curve	roof plan: eaves outline, ridges, hips, valleys, the wall line dashed, fall arrows with the pitch
`area`	list of Number	area of each roof on the slope (m2)
`info`	Text	what happened: a summary, sources and notes

How it works

Hip, gable and dutch gable use a weighted straight skeleton, so L, T, U, concave and rotated outlines work; flat and skillion keep exact curves.
pitch, eaves overhang, gable overhang, ridge direction (auto = along the long side, x, y), flip for skillion/flat falls, fascia depth.
Outputs: solids (one per layer per roof part, then fascias, barges, gutters, gablets), ridges, hips, valleys, eaves, a roof plan with the dashed wall line and fall arrows, roof records with faces (pitch, aspect from true north, area).

Stair types

stair_types

New since 0.02-alpha: arrives in the next beta.

How a stair is built (in-situ or precast concrete, steel stringers, timber), with riser and going targets and the NCC limits for its use. Cost: Free.

Inputs

Input	Type	On the component	Default	What it does
`construction`	Text	Dropdown	`concrete in-situ`	how the stair is built. One of `concrete in-situ`, `steel stringers`, `timber`, `precast`
`use`	Text	Dropdown	`public / commercial`	sets the NCC limits: public / commercial (Vol 1) or private / domestic (Vol 2). One of `public / commercial`, `private / domestic`
`name`	Text	Text field	blank	type name (blank: from the construction and sizes)
`riser`	Number	Slider 100–250	`175`	target riser (mm): each stair rounds it to a whole number of risers; NCC 115–190
`going`	Number	Slider 150–450	`280`	going (mm), nosing to nosing; NCC 250–355 public, 240–355 private
`tread`	Number	Slider 5–100	`40`	tread thickness (mm): steel and timber
`nosing`	Number	Slider 0–50	`20`	nosing projection (mm): steel and timber
`waist`	Number	Slider 80–400	`175`	waist and landing slab thickness (mm): concrete and precast
`stringer`	Text	Text field	blank	stringer depth x thickness in mm, e.g. ‘250x12’ (blank: steel 250x12 plate, timber 290x45)
`risers`	Text	Dropdown	`closed`	riser boards (steel and timber; concrete steps are always closed). One of `closed`, `open`
`plane`	Plane	Wire	—	where the swatch sits (default: world origin)
`save`	Boolean	Button	—	add this type to the Alien library

Outputs

Output	Type	What it gives you
`stair_type`	Text	stair_type record for stairs
`swatch`	list of Brep	four steps and a landing edge, 1 m wide
`colours`	list of Colour	colour per swatch solid
`section`	list of Curve	the swatch cut through its middle (stringers seen beyond)
`info`	Text	what happened: a summary, sources and notes

How it works

Construction: concrete in-situ, steel stringers, timber, precast; riser and going targets (mm), tread, nosing, waist, stringer, open or closed risers.
NCC first-pass limits: risers 115-190 mm, goings 250-355 public / 240-355 private, 2R+G 550-700, 2-18 risers a flight, landings >= 750 mm, open-riser gaps <= 125 mm.
Save adds the type to the library (kind stair_type).

Stairs

stairs

New since 0.02-alpha: arrives in the next beta.

Straight, L, U or spiral stairs fitted between two levels, with first-pass NCC checks, a plan symbol, balustrade edges and the void for the floor above. Cost: Free.

Inputs

Input	Type	On the component	Default	What it does
`levels`	list of Data	Wire	—	level records (sample: 3 storeys at 3.2 m)
`from_level`	Text	Text field	blank	lower level: name, code or index (blank: the lowest)
`to_level`	Text	Text field	blank	upper level: name, code or index (blank: the level above)
`height`	Number	Slider 0–12	`0`	floor-to-floor height (m); 0 = from the levels
`base`	list of Curve	Select in Rhino	—	base lines: each one’s start is the foot of a stair, its direction the way up (sample: a line along X at the site origin)
`align`	Text	Dropdown	`centre`	where the base line runs across the stair (looking up). One of `centre`, `left edge`, `right edge`
`shape`	Text	Dropdown	`straight`	stair shape. One of `straight`, `L (quarter landing)`, `U (half landing)`, `spiral`
`turn`	Text	Dropdown	`left`	L, U and spiral: the way the stair turns going up. One of `left`, `right`
`width`	Number	Slider 0.5–4	`1.2`	stair width (m): tread length; stringers sit outside it
`stair_type`	Data	Wire	—	stair_type record from stair_types (default: concrete in-situ, public, 175/280)
`landing`	Number	Slider 0–5	`0`	landing depth (m) in the walking direction; 0 = the stair width (at least 0.75)
`split`	Integer	Slider 0–40	`0`	L and U: risers in the first flight (0 = half)
`well`	Number	Slider 0–2	`0.1`	U: gap between the two flights; spiral: centre column radius (m)
`sides`	Text	Dropdown	`both`	which stair sides get balustrade edges (the upper floor’s void edges always do). One of `both`, `inner`, `outer`, `none`
`cut`	Number	Slider 0.2–3	`1`	plan cut height above the lower level (m): treads above it are dashed
`site`	Data	Wire	—	site record (optional): drawing scale for the plan symbols; places the sample base line

Outputs

Output	Type	What it gives you
`stairs`	list of Text	stair records
`solids`	list of Brep	flights (waist slab, or treads, risers and stringers), landings
`colours`	list of Colour	colour per solid
`plan`	list of Curve	plan at the lower level: treads, walking line with UP and arrow, cut line with break; above the cut dashed
`edges`	list of Curve	balustrade lines: open stair sides on the nosing line (flat on landings), and the upper floor’s void edges; the walkable side is on each curve’s left
`voids`	list of Curve	floor opening at the upper level, closed: for the Slabs component’s openings
`risers`	list of Integer	risers per stair
`riser`	list of Number	riser height per stair (mm)
`going`	list of Number	going per stair (mm)
`info`	Text	what happened: a summary, sources and notes

How it works

Risers are fitted to the floor-to-floor height; flights over 18 risers get landings; L and U split at the turn.
Plan: treads, walking line with UP and arrow, cut line with a break, dashed above the cut.
edges run on the nosing line (flat on landings) with the walkable side on their left; voids is the upper-floor opening for slabs.openings.
Checks per rule in the records and info (first-pass, not certification).

Balustrade types

balustrade_types

New since 0.02-alpha: arrives in the next beta.

Frameless glass, glass and posts, bars, rails, wires, sheet or timber, with heights, post spacing, gaps and a handrail, checked against the NCC barrier rules. Cost: Free.

Inputs

Input	Type	On the component	Default	What it does
`style`	Text	Dropdown	`glass and posts`	infill. One of `frameless glass`, `glass and posts`, `vertical bars`, `horizontal rails`, `wires`, `solid sheet`, `timber`
`name`	Text	Text field	blank	type name (blank: from the style and height)
`height`	Number	Slider 0.5–2	`1`	height to the top on floors and landings (m); NCC at least 1.0
`stair_height`	Number	Slider 0–2	`0`	height above the nosing line along stair flights (m); NCC at least 0.865; 0 = as height
`posts`	Number	Slider 0.3–3	`1.2`	post spacing (m); frameless glass: the pane width
`post`	Number	Slider 0–200	`0`	post size (mm), square; 0 = by style (50, timber 90)
`gap`	Number	Slider 10–300	`100`	clear gap between bars, rails or wires (mm); NCC at most 125
`bottom`	Number	Slider 0–300	`50`	gap under the infill (mm); NCC at most 125
`handrail`	Text	Dropdown	`by style`	handrail on top. One of `by style`, `round 50`, `round 42`, `square 50`, `rect 65x20`, `timber 70x42`, `none`
`infill`	Number	Slider 0–60	`0`	glass or sheet thickness, bar or rail size (mm); 0 = by style
`plane`	Plane	Wire	—	where the swatch sits (default: world origin)
`save`	Boolean	Button	—	add this type to the Alien library

Outputs

Output	Type	What it gives you
`balustrade_type`	Text	balustrade_type record for balustrades
`swatch`	list of Brep	a sample run: 1.2 m on a floor, then up a stair pitch
`colours`	list of Colour	colour per swatch solid
`elevation`	list of Curve	the swatch’s front outlines
`info`	Text	what happened: a summary, sources and notes

How it works

Styles: frameless glass, glass and posts, vertical bars, horizontal rails, wires, solid sheet, timber.
Height on floors (>= 1.0 m) and above the nosing line on stairs (>= 865 mm), openings <= 125 mm.
Save adds the type to the library (kind balustrade_type).

Balustrades

balustrades

New since 0.02-alpha: arrives in the next beta.

Balustrades along slab edges, stair edges or any curve, following a stair’s pitch, with plan and elevation linework and first-pass NCC checks. Cost: Free.

Inputs

Input	Type	On the component	Default	What it does
`path`	list of Curve	Select in Rhino	—	lines to guard: slab edges, stairs’ edges (they keep their slope), polylines, arcs, closed outlines (a sample when unwired)
`balustrade_type`	Data	Wire	—	balustrade_type record from balustrade_types (default: glass and posts, 1.0 m)
`base`	Text	Text field	blank	blank: follow each path’s own z (stair edges); else a level name, code or index, or an elevation like 3.2 (m)
`levels`	list of Data	Wire	—	level records, for a level named in base (sample levels when unwired)
`height`	Number	Slider 0–2	`0`	height override (m), floors and flights alike; 0 = the type’s
`offset`	Number	Slider -1–1	`0`	move off the path (m): + = to its left (stairs’ edges: onto the stair), inside a closed outline
`end_posts`	Boolean	Switch	on	posts at the ends of open paths
`fall`	Number	Slider 0–100	`0`	drop beside the balustrade (m), for the NCC climbing check on rails and wires; 0 = not checked
`site`	Data	Wire	—	site record (optional): places the sample

Outputs

Output	Type	What it gives you
`balustrades`	list of Text	balustrade records
`solids`	list of Brep	posts, infill (glass, bars, rails, wires, sheet), handrails
`colours`	list of Colour	colour per solid
`plan`	list of Curve	plan: posts and the balustrade’s faces, at each balustrade’s lowest point
`elevation`	list of Curve	front outlines of every part, in place (seen square-on they are the elevation)
`handrail`	list of Curve	handrail centrelines
`info`	Text	what happened: a summary, sources and notes

How it works

Follows each path’s own z (handrails parallel to the stair pitch) or sits on a level or elevation.
Posts at corners and at the spacing; curves faceted; offset to the path’s left (onto the floor or stair).
fall enables the climbable-rail check (falls over 4 m).

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Using Alien

Ready-made components

Reference

Floors, roofs and stairs

Slab types

Inputs

Outputs

Slabs

Inputs

Outputs

Roof types

Inputs

Outputs

Roofs

Inputs

Outputs

Stair types

Inputs

Outputs

Stairs

Inputs

Outputs

Balustrade types

Inputs

Outputs

Balustrades

Inputs

Outputs

​Slab types

​Inputs

​Outputs

​Slabs

​Inputs

​Outputs

​Roof types

​Inputs

​Outputs

​Roofs

​Inputs

​Outputs

​Stair types

​Inputs

​Outputs

​Stairs

​Inputs

​Outputs

​Balustrade types

​Inputs

​Outputs

​Balustrades

​Inputs

​Outputs

Slab types

Inputs

Outputs

Slabs

Inputs

Outputs

Roof types

Inputs

Outputs

Roofs

Inputs

Outputs

Stair types

Inputs

Outputs

Stairs

Inputs

Outputs

Balustrade types

Inputs

Outputs

Balustrades

Inputs

Outputs