techdrawing: Plan features

Plan features

Format

Plans are often prepared in a "set". The set includes all the information required for the purpose of the set, and may exclude views or projections which are unnecessary. A set of plans can be on standard office-sized paper or on large sheets. It can be stapled, folded or rolled as required. A set of plans can also take the form of a digital file in a proprietary format such as DWG or an exchange file format such as DXF or PDF.
Plans are often referred to as "blueprints" or "bluelines". However, the terms are rapidly becoming an anachronism, since most copies of plans that were formerly made using a chemical-printing process that yielded graphics on blue-colored paper or, alternatively, of blue-lines on white paper, have been superseded by more modern reproduction processes that yield black or multicolour lines on white paper.

[edit] Scale

Main articles: Architect's scale, Engineer's scale, and Metric scale

The three axonometric views.

Plans are usually "scale drawings", meaning that the plans are drawn at specific ratio relative to the actual size of the place or object. Various scales may be used for different drawings in a set. For example, a floor plan may be drawn at 1:48 (or 1/4"=1'-0") whereas a detailed view may be drawn at 1:24 (or 1/2"=1'-0"). Site plans are often drawn at 1" = 20' (1:240) or 1" = 30' (1:360).
In the metric system the ratios commonly are 1:5, 1:10, 1:20, 1:50, 1:100, 1:200, 1:500, 1:1000, 1:2000 and 1:5000

Views and projections

Symbols used to define whether a projection is either Third Angle (right) or First Angle (left).

Because plans represent three-dimensional objects on a two-dimensional plane, the use of views or projections is crucial to the legibility of plans. Each projection is achieved by assuming a vantage point from which to see the place or object, and a type of projection. These projection types are: