What is known as a reference point for establishing grades in construction?

A benchmark is a crucial reference point used in construction for establishing grades. It is a permanent, fixed point of known elevation that serves as a standard for measuring the height of other points on a construction site. This allows for accurate grading and leveling, which are essential for ensuring that structures are built correctly and drain properly.

Benchmarks are typically marked on a durable surface such as concrete and can be found in various locations, including survey monuments and other reliable locations. They are foundational elements in surveying and play an essential role in the layout and design of construction projects.

In contrast, a reference line is often used in different contexts, typically to indicate a direction or alignment rather than a specific elevation. A grade point could imply a specific level or elevation point but lacks the permanence and recognized standards associated with benchmarks. Control points can also refer to established points used for surveying but may not always denote a fixed elevation as benchmarks do. Thus, the term benchmark specifically encompasses the idea of a reliable reference elevation in construction grading.