A staircase is used thousands of times a year for decades. Small differences in riser height make it either easy or tiring, and its position shapes the whole structure.
Comfortable Dimensions
| Item | Typical in houses |
|---|---|
| Riser | 150 – 175 mm |
| Tread | 250 – 300 mm |
| Comfort check (2R + T) | About 600 – 640 mm |
| Width | 0.9 – 1.2 m (check local minimums) |
| Headroom | At least about 2.1 – 2.2 m |
| Steps per flight | Ideally no more than about 12 – 15 before a landing |
| Handrail | About 850 – 950 mm above the nosing |
Keep every riser in a flight the same height; a single odd step causes trips.
Working Out the Steps
For a floor-to-floor height of 3.0 m:
- 3,000 ÷ 165 ≈ 18 risers of about 167 mm
- In a dog-legged stair, 9 risers per flight
- Each flight has 8 treads: 8 × 275 mm = 2.2 m going length
Stair Types
| Type | Space | Notes |
|---|---|---|
| Dog-legged | Compact | Most common in houses; two flights with a landing |
| Straight | Long and narrow | Simple; needs length |
| L-shaped | Corner | Landing at the turn |
| External | Outside the house | Lets the upper floor be separate or rented |
Structure and Steel
The usual RCC stair is a sloping waist slab with steps cast on top. Typical details in houses:
- Waist slab about 125–175 mm thick, as designed.
- Main bars along the flight at the bottom, typically 10 or 12 mm, anchored into the landing or beam.
- Distribution bars across the flight.
- Landings supported on beams or walls.
The stair needs beams or columns at its supports, which is why its position must be fixed before the column layout is designed.
The Short Version
About 165 mm risers, 275 mm treads, 1 m width and 2.1 m+ headroom make a comfortable house stair. Choose dog-legged for compact plans, and fix the stair's position before the structure is designed.
