Where should a plumber refer to locate plumbing entry points in a building?

To determine plumbing entry points in a building, the floor plan is the most appropriate reference. The floor plan provides a detailed layout of the building, showing the placement of walls, rooms, and fixtures. It typically includes specific notations and symbols that indicate where plumbing lines, drains, and entry points should be located, allowing plumbers to understand the intended flow and functionality of water supply and drainage systems.

Elevation views primarily represent the vertical aspects of the building's exterior and do not provide detailed horizontal layouts necessary for identifying plumbing entry points. Cross-sections offer insights into how different sections of the building relate vertically but lack the comprehensive layout details needed for plumbing installation. Structural drawings focus on the building’s framework and load-bearing components, which also do not specifically address plumbing details. Therefore, for practical plumbing installation, the floor plan serves as the essential resource for identifying where plumbing entry points should be situated within the building design.