Correct Answer: B. Bifurcated
Solution:
A bifurcated stair features a wide lower flight that splits at a landing into two separate, narrower flights leading in opposite directions. This type is often used in grand entrances and public buildings to create an impressive focal point.
Correct Answer: C. 600 mm
Solution:
This is a common rule of thumb in staircase design to ensure a comfortable gait. The formula (Tread + 2 * Riser) should ideally be between 580 mm and 650 mm. 600 mm is the most commonly accepted average value for this rule.
Correct Answer: C. Winders
Solution:
Winders are steps that are narrower on one side than the other. They are used to change the direction of the stairs without a landing, commonly found in spiral or L-shaped staircases.
Correct Answer: A. Floor space is limited
Solution:
The primary advantage of a spiral staircase is its small footprint. It occupies a minimal amount of floor area, making it an ideal choice for compact spaces where a conventional staircase would not fit.
Correct Answer: C. Soffit
Solution:
The soffit is the exposed underside of a structural element, which in the case of a staircase, is the ceiling-like surface underneath the flight of stairs.
Correct Answer: B. Balustrade
Solution:
A balustrade is the collective term for the entire assembly of handrails, newel posts, and balusters (or spindles) that forms the protective barrier along the side of a staircase or balcony.
Correct Answer: B. 0.9 m
Solution:
While codes may vary slightly, a width of 90 cm (0.9 m) is a common minimum standard for residential stairs to allow for comfortable passage and moving furniture. Public buildings often require wider stairs.
Correct Answer: C. Open-riser Stair
Solution:
An open-riser stair, also known as a floating stair, has gaps between the treads where the risers would normally be. This design creates a sense of openness and is often used in modern architecture.
Correct Answer: B. Balusters
Solution:
Balusters are the vertical members of a balustrade that fill the space between the handrail and the stringer or tread. They provide support for the handrail and prevent falls.
Correct Answer: B. Going
Solution:
The 'going' of a flight is the horizontal distance from the front of the first nosing to the front of the last nosing in that flight. It is essentially the horizontal run of the staircase.
Correct Answer: B. 12
Solution:
To ensure safety and provide resting points, building regulations for public spaces often limit the number of consecutive risers in a flight. A common maximum is 12 risers before a landing is required.
Correct Answer: B. Spiral stair
Solution:
This is the defining characteristic of a spiral stair. The treads wind around a central column, forming a helical shape. A helical stair is similar but has an open well instead of a central post.
Correct Answer: D. 2R + T = 60
Solution:
This is another common design rule for comfortable stairs, similar to the one in Q17 but using centimeters. The sum of twice the riser and one tread should be approximately 60 cm (or 600 mm). For example, a 17.5 cm riser and a 25 cm tread gives 2(17.5) + 25 = 60.
Correct Answer: C. Nosing
Solution:
The nosing is the front edge of the step. It typically overhangs the riser below to provide a bit more tread depth and improve safety by making the step edge more visible.
Correct Answer: C. Geometrical
Solution:
Geometrical stairs are defined by their complex, continuous curves in both the stringers and handrails. They do not rely on newel posts at turns and instead use winders and curved sections to create a smooth, flowing ascent.