Stair types: identify the incorrect statement about dog-legged, open newel, and geometric (geometrical) stairs

Introduction / Context:
Stair layouts are categorized by how flights turn and whether a central well or newel opening exists. Understanding the differences among dog-legged, open newel, and geometric stairs aids in circulation design and measurement for BOQs.

Given Data / Assumptions:

• Dog-legged stairs comprise two flights in opposite directions with a half-space landing and no intervening well.
• Open newel stairs feature an open rectangular well between flights.
• Geometric (geometrical) stairs have curved stringers and a curved well; winders replace large landings.

Concept / Approach:
The incorrect statement is the one that generalizes geometric stairs as necessarily having two quarter-space landings. In fact, geometric stairs typically avoid large landings, using winders around a well to achieve smooth curvature; landings, if any, are incidental. The other statements match standard definitions.

Step-by-Step Solution:
Check dog-legged: no well between flights → correct.Check open newel: rectangular well provided → correct.Check geometric: curved well/stringers → correct.Identify incorrect: “two quarter-space landings” is not a defining feature of geometric stairs.

Verification / Alternative check:
Architectural references depict dog-legged with half-landing and no well; open newel with central void; geometric with winders around a curved well.

Why Other Options Are Wrong:
a, b, c align with accepted stair typologies.e (None) is invalid because one statement (d) is clearly incorrect.

Common Pitfalls:
Confusing open newel stairs (rectangular void) with spiral/helical stairs; assuming all turning stairs must have quarter-space landings.

Final Answer:
In a geometrical stair, two quarter-space landings are provided as a rule is the incorrect statement.