A stair turning one right angle is known as
Try it first: pick an option, then read the explanation.
Understanding Staircase Geometry
Staircases are classified based on their shape and the way they change direction. The "turn" of a stair refers to the total angle of direction change from the bottom of the stair to the top. A right angle is a 90-degree turn.
Quarter-Turn Stairs: As the name implies, this type of staircase makes a single turn of 90 degrees (a quarter of a full 360-degree circle). This turn can be achieved with a small landing or with angled steps called winders. They are commonly used when the available length for the staircase is limited, but there is sufficient width.
Detailed Analysis of the Options
Let's examine the degree of turn for each type of staircase mentioned.
(c) Quarter-Turn Stairs
Why it's correct: This stair changes the direction of the flight by one right angle (90°). This is the precise definition given in the question.
(a) Dog-Legged Stairs
Why it's incorrect: This is a type of Half-Turn (180°) stair. It consists of two parallel flights running in opposite directions, connected by a landing. There is no space between the two flights.
(b) Half Turn Stairs
Why it's incorrect: This is a general category for any stair that turns 180°. While a dog-legged stair is a half-turn stair, the question specifically asks for a single right-angle (90°) turn.
(d) Open Newel Stairs
Why it's incorrect: This is another type of Half-Turn (180°) stair. Unlike a dog-legged stair, it features a well or opening between the two flights, making it feel more spacious. It still completes a 180° turn.
Glossary of Stair Turn Types
Understanding the different classifications of stair turns is key to selecting the right design for a space.
- Quarter-Turn (90°): The flight turns at a right angle, to the left or right. Ideal for corners.
- Half-Turn (180°): The direction of travel reverses. Dog-legged and Open Newel are the most common types. Very efficient for multi-story buildings.
- Three-Quarter Turn (270°): The stair turns through three right angles. Often used to access a higher level in a compact space.
- Continuous Stairs: These stairs have no intermediate landings or newel posts and can be circular or spiral in shape.