An architectural drawing or architect's drawing is a technical drawing of a building (or building project) that falls within the definition of architecture. Architectural drawings are used by architects and others for a number of purposes: to develop a design idea into a coherent proposal, to communicate ideas and concepts, to convince clients of the merits of a design, to enable a building contractor to construct it, as a record of the completed work, and to make a record of a building that already exists.
Architectural drawings are drawn according to a set of conventions, which include particular views (floor plan, section etc.), sheet sizes, units of measurement and scales, annotation and cross referencing. Conventionally, drawings were made in ink on paper or a similar material, and any copies required had to be laboriously made by hand. The twentieth century saw a shift to drawing on tracing paper, so that mechanical copies could be run off efficiently.
The development of the computer had a major impact on the methods used to design and create technical drawings,[1] making manual draughting almost obsolete, and opening up new possibilities of form using organic shapes and complex geometry. Today the vast majority of drawings are created using CAD software.[2][3]
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The size of drawings reflects the materials available and the size that is convenient to transport – rolled up or folded, laid out on a table, or pinned up on a wall. The draughting process may impose limitations on the size that is realistically workable. Sizes are determined by a consistent paper size system, according to local usage. Normally the largest paper size used in modern architectural practice is ISO A0 (841 × 1,189 mm/33.1 × 46.8 in) or in the USA Arch E (762 × 1,067 mm/30 × 42 in), although there is a Large E size (915 × 1,220 mm/36 × 48 in) which does not have an ISO equivalent.[4]
Architectural drawings are drawn to scale, so that relative sizes are correctly represented. The scale is chosen both to ensure the whole building will fit on the chosen sheet size, and to show the required amount of detail. At the scale of one eighth of an inch to one foot (1/96th) or the metric equivalent 1 to 100, walls are typically shown as simple outlines corresponding to the overall thickness. At a larger scale, half an inch to one foot (1/24th) or the nearest common metric equivalent 1 to 20, the layers of different materials that make up the wall construction are shown. 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), while lacking the simple logic of the metric system, 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.
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.
A floor plan is the most fundamental architectural diagram, a view from above showing the arrangement of spaces in 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 three feet / one metre 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 dotted lines.
Geometrically, plan view is defined as a vertical orthographic projection of an object on to a horizontal plane, with the horizontal plane cutting through the building.
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 plan may need to show adjoining streets to demonstrate how the design fits in to the urban fabric. Within the site boundary, the site plan gives an overview of the entire scope of work. It shows the buildings (if any) already existing and those that are proposed, usually as a building footprint; roads, parking lots, footpaths, hard landscaping, trees and planting. For a construction project, the site plan also needs to show all the services connections: drainage and sewer lines, water supply, electrical and communications cables, exterior lighting etc.[5][6]
Site plans are commonly used to represent a building proposal prior to detailed design: drawing up a site plan is a tool for deciding both the site layout and the size and orientation of proposed new buildings. A site plan is used to verify that a proposal complies with local development codes, including restrictions on historical sites. In this context the site plan forms part of a legal agreement, and there may be a requirement for it to be drawn up by a licenced professional: architect, engineer, landscape architect or land surveyor.[7]
An elevation is a view of a building seen from one side, a flat representation of one façade. This is the most common view used to describe the external appearance of a building. Each elevation is labelled in relation to the compass direction it faces, e.g. the north elevation of a building is the side that most closely faces north.[8] Buildings are rarely a simple rectangular shape in plan, so a typical elevation may show all the parts of the building that are seen from a particular direction.
Geometrically, an elevation is a horizontal orthographic projection of a building on to a vertical plane, the vertical plane normally being parallel to one side of the building.
Architects also use the word elevation as a synonym for façade, so the north elevation is literally the north wall of the building.
A cross section, also simply called a section, represents a vertical plane cut through the object, in the same way as a floor plan is a horizontal section viewed from the top. In the section view, everything cut by the section plane is shown as a bold line, often with a solid fill to show objects that are cut through, and anything seen beyond generally shown in a thinner line. Sections are used to describe the relationship between different levels of a building. In the Observatorium drawing illustrated here, the section shows the dome seen from the outside, a second dome that can only be seen inside the building, and the way the space between the two accommodates a large astronomical telescope: relationships that would be difficult to understand from plans alone.
A sectional elevation is a combination of a cross section, with elevations of other parts of the building seen beyond the section plane.
Geometrically, a cross section is a horizontal orthographic projection of a building on to a vertical plane, with the vertical plane cutting through the building.
Isometric and axonometric projections are a simple way of representing a three dimensional object, keeping the elements to scale and showing the relationship between several sides of the same object, so that the complexities of a shape can be clearly understood.
There is some confusion about the terms isometric and axonometric. “Axonometric is a word that has been used by architects for hundreds of years. Engineers use the word axonometric as a generic term to include isometric, diametric and trimetric drawings.”[9] This article uses the terms in the architecture-specific sense.
Despite fairly complex geometrical explanations, for the purposes of practical draughting the difference between isometric and axonometric is simple (see diagram above). In both, the plan is drawn on a skewed or rotated grid, and the verticals are projected vertically on the page. All lines are drawn to scale so that relationships between elements are accurate. In many cases a different scale is required for different axes, and again this can be calculated but in practice was often simply estimated by eye.
Traditional draughting techniques used 30-60 and 45 degree set squares, and that determined the angles used in these views. Once the adjustable square became common those limitations were lifted.
The axonometric gained in popularity in the twentieth century, not just as a convenient diagram but as a formal presentation technique, adopted in particular by the Modern Movement.[9] Axonometric drawings feature prominently in the influential 1970's drawings of Michael Graves, James Stirling and others, using not only straightforward views but worms-eye view, unusually and exaggerated rotations of the plan, and exploded elements.[13]
The axonometric view is not readily generated by CAD programmes, which work best by generating a view from a three dimensional model. Consequently it is now little used except to illustrate relatively simple construction details.
Detail drawings show a small part of the construction at a larger scale, to show how the component parts fit together. They are also used to show small surface details, for example decorative elements. Section drawings at large scale are a standard way of showing building construction details, typically showing complex junctions (such as floor to wall junction, window openings, eaves and roof apex) that cannot be clearly shown on a drawing that includes the full height of the building. A full set of construction details needs to show plan details as well as vertical section details. One detail is seldom produced in isolation: a set of details shows the information needed to understand the construction in three dimensions. Typical scales for details are 1/10, 1/5 and full size.
In traditional construction, many details were so fully standardised, that few detail drawings were required to construct a building. For example, the construction of a sash window would be left to the carpenter, who would fully understand what was required, but unique decorative details of the facade would be drawn up in detail. In contrast, modern buildings need to be fully detailed because of the proliferation of different products, methods and possible solutions.
Perspective in drawing is an approximate representation on a flat surface of an image as it is perceived by the eye. The key concepts here are:
The basic categorization of artificial perspective is by the number of vanishing points:
The normal convention is architectural perspective is to use two-point perspective, with all the verticals drawn as verticals on the page.
Three-point perspective gives a casual, photographic snapshot effect. In professional architectural photography, conversely, a view camera or a perspective control lens is used to eliminate the third vanishing point, so that all the verticals are vertical on the photograph, as with the perspective convention. This can also be done by digital manipulation of a photograph taken with a normal camera.
Aerial perspective is a technique in painting, for indicating distance by approximating the effect of the atmosphere on distant objects. In daylight, as an ordinary object gets further from the eye, its contrast with the background is reduced, its colour saturation is reduced, and its colour becomes more blue. Not to be confused with aerial view or bird's eye view, which is the view as seen (or imagined) from a high vantage point. In J M Gandy's perspective (see illustration above) of the Bank of England, Gandy portrayed the building as a picturesque ruin in order to show the internal plan arrangement, a precursor of the cutaway view.[14]
A montage image is produced by superimposing a perspective image of a building on to a photographic background. Care is needed to record the position from which the photograph was taken, and to generate the perspective using the same viewpoint. This technique is popular in computer visualisation, where the building can be photorealistically rendered, and the final image is intended to be almost indistinguishable from a photograph.
Architectural drawings are produced for a specific purpose, and can be classified accordingly. Several elements are often included on the same sheet, for example a sheet showing a plan together with the principal façade.
Drawings intended to explain a scheme and to promote its merits. Working drawings may include tones or hatches to emphasise different materials, but they are diagrams, not intended to appear realistic. Basic presentation drawings typically include people, vehicles and trees, taken from a library of such images, and are otherwise very similar in style to working drawings. Rendering is the art of adding surface textures and shadows to show the visual qualities of a building more realistically. An architectural illustrator or graphic designer may be employed to prepare specialist presentation images, usually perspectives or highly finished site plans, floor plans and elevations etc.
Measured drawings of existing land, structures and buildings. Architects need an accurate set of survey drawings as a basis for their working drawings, to establish exact dimensions for the construction work. Surveys are usually measured and drawn up by specialist land surveyors.
Historically, architects have made record drawings in order to understand and emulate the great architecture known to them. In the Renaissance, architects from all over Europe studied and recorded the remains of the Roman and Greek civilizations, and used these influences to develop the architecture of the period. Records are made both individually, for local purposes, and on a large scale for publication. Historic surveys worth referring to include:
Record drawings are also used in construction projects, where "as-built" drawings of the completed building take account of all the variations made during the course of construction.
A comprehensive set of drawings used in a building construction project: these will include not only architect's drawings but structural and services engineer's drawings etc. Working drawings logically subdivide into location, assembly and component drawings.[12]
Until the latter part of the twentieth century, all architectural drawings were manually produced, either by architects or by trained (but less skilled) draughtsmen (or drafters), who did not generate the design, although they made many of the less important decisions. This system continues with CAD draughting: many design architects have little or no knowledge of CAD software programmes and rely upon others to take their designs beyond the sketch stage. Draughtsmen may specialize in a type of structure, such as residential or commercial, or in a type of construction: timber frame, reinforced concrete, prefabrication etc.[15]
The traditional tools of the architect were the drawing board or draughting table, T-square and set squares, protractor, compasses, pencil and drawing pens of different types.[16] Drawings were made on vellum, coated linen, and on tracing paper. Lettering would either be done by hand, mechanically using a stencil, or a combination of the two. Ink lines were drawn with a ruling pen, a relatively sophisticated device similar to a dip-in pen but with adjustable line width, capable of producing a very fine controlled line width. Ink pens had to be dipped into ink frequently. Draughtsmen worked standing up, and kept the ink on a separate table to avoid spilling ink on the drawing.
Twentieth century developments include the parallel motion drawing board, and more complicated improvements on the basic T-square. The development of reliable technical drawing pens allowed for faster draughting and stencilled lettering. Letraset dry transfer lettering and half-tone sheets were popular from the 1970s until computers made those processes obsolete.
Computer-aided design is the use of computer software to create drawings. Today the vast majority of technical drawings of all kinds are made using CAD. Instead of drawing lines on paper, the computer records similar information electronically. There are many advantages to this system: repetition is reduced because complex elements can be copied, duplicated and stored for re-use. Errors can be deleted, and the speed of draughting allows many permutations to be tried before the design is finalised. On the other hand, CAD drawing encourages a proliferation of detail and increased expectations of accuracy, aspects which reduce the efficiency originally expected from the move to computerisation.
CAD programmes, for example the worldwide market leader AutoCAD, are complex and require both training and experience before the operator becomes fully productive. Consequently skilled CAD operators are often divorced from the design process. There are other more basic programmes such as SketchUp that allow for more intuitive drawing and are intended as a design tool.
CAD is used to create all kinds of drawings, from working drawings to photorealistic perspective views. Architectural renderings (also called visualisations) are made by creating a three-dimensional model using CAD. The model can be viewed from any direction to find the most useful viewpoints. Different software (for example Autodesk 3ds Max) is then used to apply colour and texture to surfaces, and to represent shadows and reflections. The result can be accurately combined with photographic elements: people, cars, background landscape.
An architectural animation is a short film showing how a proposed building will look: the moving image makes three-dimensional forms much easier to understand. An animation is generated from a series of hundreds or even thousands of still images, each made in the same way as an architectural visualisation. A computer-generated building is created using a CAD programme, and that is used to create more or less realistic views from a sequence of viewpoints. The simplest animations use a moving viewpoint, while more complex animations can include moving objects: people, vehicles and so on.
Reprographics or reprography covers a variety of technologies, media, and support services used to make multiple copies of original drawings. Prints of architectural drawings are still sometimes called blueprints, after one of the early processes which produced a white line on blue paper. The process was superseded by the dye-line print system which prints black on white coated paper. The standard modern processes are the ink-jet printer, laser printer and photocopier, of which the ink-jet and laser printers are commonly used for large-format printing. Although colour printing is now commonplace, it remains expensive above A3 size, and architect's working drawings still tend to adhere to the black and white / greyscale aesthetic.