Details

Based on National CAD Standard 3.1 PDF pages 409

Details show the geometry, materials, connections, and locations of building elements with sufficient information so that the elements can be fabricated or purchased, and constructed. Do not provide either more or less information than is required. For example, a manufactured item should only be shown as an abstracted, or simplified, outline, since its specific design is already determined by the manufacturer. Where several alternative manufactured products or systems are acceptable, the detail should be general enough to represent all of them.

Account for tolerances that are specified for construction elements. For example, do not represent the position of a curtain wall mullion as being in contact with the edge of the concrete slab to which it is fastened, since the tolerance of the concrete slab — it's expected deviation from an idealized position in space — is inconsistent with such a mullion location.

There are three classes of details:

Horizontal (plan) details, typically keyed in from floor plans or large-scale plans;
Vertical (section) details, typically keyed in from wall or building sections, or from elevations;
3D details, e.g., isometric drawings, are used where 2D drawings are insufficient.

Detailed dimensions should not be reproduced on plans or sections, except where such redundancy is useful or necessary.