Construction details are drawn to a larger scale, in some cases full size (1 to 1 scale). Scale drawings enable dimensions to be "read" off the drawing, i.e. measured directly. Imperial scales (feet and inches) are equally readable using an ordinary ruler. On a one-eighth inch to one-foot scale drawing, the one-eighth divisions on the ruler can be read off as feet. Architects normally use a scale ruler with different scales marked on each edge. A third method, used by builders in estimating, is to measure directly off the drawing and multiply by the scale factor. Dimensions can be measured off drawings made on a stable medium such as vellum. All processes of reproduction introduce small errors, especially now that different copying methods mean that the same drawing may be re-copied, or copies made in several different ways. Consequently, dimensions need to be written ("figured") on the drawing. The disclaimer "Do not scale off dimensions" is commonly inscribed on architects' drawings, to guard against errors arising in the copying process. Standard views used in architectural drawing This section deals with the conventional views used to represent a building or structure. See the Types of architectural drawing section below for drawings classified according to their purpose. Floor plan A floor plan is the most fundamental architectural diagram, a view from above showing the arrangement of spaces in a building in the same way as a map, but showing the arrangement at a particular level of a building. Technically it is a horizontal section cut through a building (conventionally at four feet / one metre and twenty centimetres above floor level), showing walls, windows and door openings, and other features at that level. The plan view includes anything that could be seen below that level: the floor, stairs (but only up to the plan level), fittings, and sometimes furniture. Objects above the plan level (e.g. beams overhead) can be indicated as dashed lines. Geometrically, plan view is defined as a vertical orthographic projection of an object onto a horizontal plane, with the horizontal plane cutting through the building. Site plan A site plan is a specific type of plan, showing the whole context of a building or group of buildings. A site plan shows property boundaries and means of access to the site, and nearby structures if they are relevant to the design. For a development on an urban site, the site