--- title: "Essential requirements and types of stair by shape" subject: "Building Technology" chapter: 5 key: "semester_6/building_technology:stair-requirements-shape-types" source: https://www.bctengineer.com/q/semester_6/building_technology/stair-requirements-shape-types site: BCT Engineering --- # Essential requirements and types of stair by shape Building Technology · Chapter 5: Stair, lifts and escalators - Asked in: 2075 Bhadra, 4 marks - Video: [TYPES OF STAIRS USED IN CONSTRUCTION | Civil Engineering Basic Knowledge](https://www.youtube.com/watch?v=l8KVltejY7U) — qLearnify (EN) - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/building_technology/stair-requirements-shape-types - Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-5 ## Question What are the essential requirements of good stair? State different types of stair as per shape. ## Short answer Requirements: accessible, width, riser/tread (2R+T 580-600 mm), pitch 25-40 deg, 3-12 steps, landings, headroom 2.0-2.2 m, strength, handrails, non-slip. Shape types: straight, quarter-turn, dog-legged, open-well, half-turn, three-quarter turn, bifurcated, geometrical, spiral. ## Answer #### Essential requirements of a good stair 1. **Location:** easily accessible, centrally placed, well lit and ventilated, and near the main entrance; not through rooms. 2. **Width:** residential at least 0.9-1.0 m, public buildings 1.5 m or more (as per NBC and local building bye-laws), so that two persons can pass. 3. **Easy and safe ascent:** riser 150-175 mm (public buildings not more than 150 mm), tread 250-300 mm; $2R + T$ about 580-600 mm; all steps in one flight equal. 4. **Pitch:** between 25 and 40 degrees. 5. **Number of steps per flight:** not more than 12 and not less than 3. 6. **Landings:** provided at turns and between flights, with a width not less than the stair width. 7. **Headroom:** at least 2.0-2.2 m clear above every step. 8. **Strength and fire resistance:** strong enough for the live load; fire-resistant material, with a separate fire-escape stair in tall buildings. 9. **Handrails and balustrades:** about 0.9 m high, strong and safe for children. 10. **Surface:** non-slip treads, good lighting and ventilation, durable and pleasing in appearance. #### Types of stair as per shape | Type | Description | |---|---| | Straight (single flight) | One continuous flight between two floors, no turn | | Quarter-turn | Direction changes by 90 degrees at a quarter-space landing | | Dog-legged | Two flights in opposite directions with a half-space landing and no well between the flights | | Open-newel / open-well | Two or more flights with a clear well between them | | Half-turn (two-flight) | Turn of 180 degrees, either dog-legged or open-well | | Three-quarter turn | Three flights turning through 270 degrees around a well | | Bifurcated (branching) | One wide flight splits into two narrower flights at a landing | | Geometrical | Curved (circular or elliptical) flights round an open well, without newel posts; continuous handrail | | Spiral / circular (helical) | Winder steps radiating round a central post or on a circular plan; saves space | ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What minimum width suits public buildings? A. 1.5 m or more B. 0.5 m C. 0.9 m exactly D. 0.3 m Answer: A. Residential is 0.9-1.0 m; public 1.5 m or more. (Key point: Public stair width) 2. What should landing width be? A. Half the stair width B. Not less than the stair width C. Anything D. Double the stair width always Answer: B. A narrower landing would bottleneck. (Key point: Landing width) 3. What distinguishes an open-newel stair? A. No well B. Single flight C. Two flights with a clear well between them D. Circular steps Answer: C. Dog-legged has no well. (Key point: Open well) 4. How much does a three-quarter turn stair turn? A. 90 degrees B. 180 degrees C. 360 degrees D. 270 degrees through three flights Answer: D. It winds round a well. 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