stairs
Let an agent treat stairs as a building element governed by geometry, safety and accessibility rules, and know when stairs are a barrier that needs an alternative.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
written by Claude from model knowledge without web access - no source was read, every claim is a lead to verify
Researched by: Claude
Purpose and description
Let an agent treat stairs as a building element governed by geometry, safety and accessibility rules, and know when stairs are a barrier that needs an alternative.
A construction of steps that lets people move on foot between levels, made of treads and risers arranged in one or more flights, with landings and usually handrails.
What it is for: Moving people on foot between floors or levels, and providing escape routes in emergencies.
It can be climb and descend them, which some people cannot do; design and build them, to building code geometry; inspect them, for condition and compliance; provide an alternative, such as a lift or ramp, where access requires one.
Distinguishing features
Consistent step geometry, which is what makes stairs safe
A building element with code requirements, unlike informal steps
A barrier to wheelchair users and some others, needing alternatives
Escape stairs have extra requirements for fire protection and width
What it looks like
A series of horizontal treads rising in equal steps, with risers between them, landings at intervals, and handrails or balustrades along open sides.
Physical character
riser height: 150-190 mm - codes set maximum riser heights
tread depth: 250-300 mm
pitch: 25-42 degrees - steeper than about 42 degrees is usually a ladder or ship stair
handrail height: 850-1000 mm
How it is recognised
Regular treads and risers forming a flight
Handrails and balustrades along the sides
Stiles and ladders are related but steeper and treated differently by codes
Related models
is part of - stairs are a building element
is alternative to - accessibility requires alternatives
is regulated by - geometry, guarding and fire rules
is confused with - an escalator is a moving machine with its own standards
In practice
Families and kinds
by shape: straight, L-shaped, U-shaped, spiral, curved
by use: main, service, escape, external, monumental
by material: timber, concrete, steel, stone
related forms: stiles, ladders, escalators
Standards and regulation
National building codes on stair geometry and guarding
Fire codes on escape stairs
Accessibility standards such as ISO 21542
Failure modes and hazards
Falls, among the most common causes of injury at home
Irregular risers or worn treads that trip people
Missing or low handrails and guarding
Blocked escape stairs
Also called
+38
Where this came from
wikidata · CC0 1.0
Also registered as vr.tr.stairs
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 4 bundles · 8 layers · 8 findings · 16 questions.
Geometry Rise, going and pitch.
Consistent geometry is what makes stairs safe to use.
Steps
Riser and tread dimensions.
Step dimensions
The measured riser and tread sizes.
- What are the riser height and tread depth, and are they consistent? measurement
- Do they comply with the applicable code? boundary
Layout
Flights, landings and width.
Stair layout
Flights, landings and clear width.
- How many flights and landings are there, and how wide is the stair? measurement
- Is headroom sufficient along the whole flight? measurement
Safety Guarding and slip resistance.
Falls on stairs cause serious injuries, and most causes are designable out.
Handrails and guarding
Rails and balustrades.
Guarding provision
Handrail and guard heights and continuity.
- Are handrails and guards present, continuous and at the right height? measurement
- Can a child climb or pass through the guarding? boundary
Surface
Slip resistance and visibility.
Surface condition
Nosings, contrast and slip resistance.
- Are the treads slip resistant, with visible nosings? measurement
- Is lighting adequate? measurement
Access and escape Who can use them and in emergencies.
Stairs exclude some people and are the escape route for others.
Accessibility
Alternatives for those who cannot use stairs.
Alternatives provided
Lifts, ramps or evacuation aids.
- What alternative exists for people who cannot use these stairs? action
- How are they evacuated in an emergency? action
Escape role
Fire protection and capacity.
Escape provision
Whether the stair is an escape route and its protection.
- Is this an escape stair, and how is it protected from fire and smoke? definition
- Is it kept clear? measurement
Construction and condition What it is made of and its state.
Material and condition decide maintenance and risk over time.
Material
Structure and finishes.
Construction
The structure and finishes.
- What is the stair made of, and how is it supported? definition
- What load is it designed for? measurement
Condition
Wear and damage.
Condition survey
Wear, damage and repairs needed.
- What wear or damage is present? measurement
- Who is responsible for repairs? provenance
What the second pass must settle
- Should escape stairs be a separate entry from stairs in general?
- How should accessibility alternatives be linked to stairs in a building model?
- Which geometry rules should the model carry across jurisdictions?