Level (elevation datum)

In Turkish practice, kot is the level, or spot elevation, of a surface relative to a fixed datum. On architectural drawings the datum is usually the finished floor of the entrance level, written as ±0.00; floors above get positive values in metres and basements or foundations get negative ones. On site, these project levels are tied back to survey levels referenced to sea level.

Reading levels on a drawing

On plans, a level appears as a small marker on the floor with a number next to it. On sections and elevations, triangular or semicircular level symbols sit at the end of each floor line. Two kinds of level are kept apart: the structural level, which is the top of the bare slab, and the finished level, measured after screed, tiles or timber flooring are in place. Mixing them up is how stair risers, door thresholds and wet-room steps end up wrong. The site plan should always state which survey level the building’s ±0.00 corresponds to, because that single number drives excavation depth and the design of the garden around the building.

Levels in the model and the render

Placing every floor at its correct level when you build a 3D model saves a lot of trouble later. In landscape, ramp and stair work, matching terrain levels to building levels is the detail that decides whether a building sits convincingly on its site in the final render.