Part 1 of 2
Stairs
Last reviewed 16 Sept 2026 · 9 min read
Stairs
A stair is a series of steps arranged to connect different floors or levels. A staircase is the room or enclosure containing the stair.
Technical terms
| Term | Meaning |
|---|---|
| Step | Portion of a stair comprising a tread and a riser |
| Tread | Horizontal upper surface of a step on which the foot is placed |
| Riser | Vertical portion between two consecutive treads |
| Rise | Vertical height of a step (from top of one tread to the top of the next) |
| Going | Horizontal distance between two consecutive risers (effective tread width); total going of a flight = sum of goings |
| Nosing | Projecting edge of the tread beyond the face of the riser (rounded) |
| Scotia | Moulding under the nosing to improve appearance |
| Flight | An uninterrupted series of steps between two landings |
| Landing | Level platform at the top/bottom of a flight or between flights — half-space landing (full width across two flights, turning 180°) and quarter-space landing (turning 90°) |
| Pitch (slope) | Angle of inclination of the stair with the horizontal |
| Line of nosing | Imaginary line through the nosings — parallel to the pitch |
| Headroom | Minimum clear vertical distance from the line of nosing (or landing) to the ceiling/soffit above |
| Handrail | Rail provided for support along the side of the flight |
| Baluster | Vertical member supporting the handrail |
| Balustrade | Row of balusters with the handrail |
| Newel post | Heavy post at the start, end or turn of a flight supporting the handrail and strings |
| String (stringer) | Inclined member supporting the ends of the steps — closed (housed) string (steps housed in it) and open (cut) string (profile cut to the steps) |
| Winders | Tapering steps used to change direction (instead of a landing) — less safe |
| Flyers | Ordinary parallel (rectangular) steps |
| Waist | Thickness of the inclined slab of an RCC stair below the steps |
| Soffit | Underside of the stair |
| Well | Space between the outer strings of flights (open well stairs) |
Requirements of a good stair
- Location — easily accessible from all rooms/areas, preferably near the entrance and centrally located; well lit and ventilated; fire escape considerations in large buildings.
- Width — adequate for traffic and furniture movement: commonly at least about 0.9–1.0 m in residences and 1.5 m or more in public buildings (as per bye-laws and fire codes).
- Rise and tread:
- Rise commonly 150–190 mm (lower in public buildings, about 150 mm); tread commonly 250–300 mm.
- Comfortable relations (empirical):
- mm (commonly about 600 mm)
- mm²
- mm
- All risers and treads in a flight must be uniform.
- Number of steps per flight — commonly not more than about 12–15 and not less than about 3.
- Pitch — generally between about 25° and 40° (about 30–35° comfortable).
- Headroom — at least about 2.1 m (2.0 m minimum in some codes) above the line of nosing.
- Landings — width not less than the width of the stair.
- Handrails — at a height of about 850–1000 mm above the nosing line; on both sides for wider stairs; balusters closely spaced for child safety.
- Winders avoided (or kept to a minimum); if used, placed at the bottom.
- Materials — strong, fire resistant, non-slippery treads (nosing strips).
- Balustrades on open sides.
Types of stairs
| Type | Arrangement | Remarks |
|---|---|---|
| Straight stair | All steps in one direction — single flight or flights with intermediate landings | Simple; needs long narrow space; porches, narrow staircases, cellars |
| Dog-legged stair | Two adjacent flights running in opposite directions with a half-space landing, no well between them (outer strings in the same vertical plane) | Economical in space — most common in residential buildings |
| Open newel (open well) stair | Flights with a well between them; turns at quarter-space landings (or half-turn with a well) | Better appearance, more light, space for lifts in the well |
| Quarter-turn stair | Direction changes by 90° with a quarter-space landing (or winders) | Corners of halls |
| Half-turn stair | Direction changes by 180° (dog-legged or open well) | Common |
| Three-quarter-turn stair | Direction changes by 270° | Towers, compact spaces |
| Geometrical stair | Curved flights (circular/elliptical) with a continuous string and handrail, no newel posts | Architectural, elegant |
| Bifurcated stair | A wide flight splits into two narrower flights at a landing, going in opposite directions | Public buildings, entrance halls |
| Spiral stair | Steps radiating around a central post (newel), winding as winders | Very limited space, emergency and service stairs, towers (often steel or precast) |
| Helical stair | Curved about a vertical axis without a central column (circular in plan) | Architectural RCC/steel stairs |
| Ladders | Steep access | Lofts, service access |
Materials
| Material | Features |
|---|---|
| Timber | Light, easy to build; poor fire resistance — residential interiors, lofts |
| Stone | Durable, strong — steps cantilevered from walls or supported on strings; heavy |
| Brick | Solid steps built on brickwork — low buildings, external steps |
| Steel | Strings with pressed/chequered plate or grating treads — industrial buildings, fire escapes, spiral stairs |
| RCC | Most common — strong, fire resistant, durable, any shape; cast in situ or precast |
| Precast concrete | Precast steps or entire flights — speed |
| Glass, aluminium, composite | Architectural stairs |
RCC stairs — structural behaviour
| Type | Behaviour |
|---|---|
| Stairs spanning longitudinally (waist slab type) | The inclined waist slab spans along the flight between supports (landing beams, walls or floor slabs); main reinforcement along the slope in the waist; steps are formed over the slab |
| Stairs spanning transversely | Each step spans across the width between side walls/stringer beams, or cantilevers from a wall or a central beam (cantilever steps) |
| Folded plate (slabless) stairs | Treads and risers act together as a folded plate without a separate waist |
| Stairs with stringer beams | Inclined beams on one or both sides carry the steps |
Loads: self-weight of waist and steps, floor finish, and live load as per IS 875 (Part 2) — commonly about 3 kN/m² for residential buildings and higher (about 4–5 kN/m²) for public buildings and areas subject to crowding. IS 456 gives guidance on effective span and load distribution for stairs.