Basic building terminology: “Ceiling height” of a room is measured as the vertical distance

Introduction / Context:
Clear definitions of dimensional terms ensure consistency in drawings, approvals, and measurement for contracts. “Ceiling height” is a commonly specified dimension in building byelaws and ergonomics.

Given Data / Assumptions:

• The room has a finished floor and a finished ceiling surface (plaster, false ceiling, or exposed slab).
• We need the definition applicable for habitable room height checks.

Concept / Approach:
Ceiling height is the vertical distance between the finished floor level (FFL) and the finished ceiling surface. Outdoor ground levels or roof levels are irrelevant to this interior dimension. Where a false ceiling is installed, most codes consider the clear height up to the lowest finished ceiling plane for habitable-space requirements.

Step-by-Step Solution:
Identify the two interior reference planes: finished floor and finished ceiling.Ignore external ground or roof references, as they do not define interior clear height.Select the description matching interior vertical clearance.

Verification / Alternative check:
Building codes specify minimum ceiling heights (e.g., around 2.6 m for main rooms in many jurisdictions) measured from FFL to finished ceiling/soffit.

Why Other Options Are Wrong:
Options involving ground or roof levels refer to external dimensions, not room interior clearance.

Common Pitfalls:
Measuring to the slab soffit when a lower false ceiling is present; not accounting for floor finishes thickness when checking minimum height.

Final Answer:
Between the finished ceiling and finished floor level of the same room.