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Last edited 18 Nov 2020
Orthographic projection is a technique for drawing a three dimensional object in two dimensions, by ‘projecting’ its surfaces into a two dimensional representation, where the projection lines are orthogonal to (perpendicular to) the projection plane (that is, there is no foreshortening or perspective).
Floor plans are a form of orthographic projection that can be used to show the layout of rooms within buildings, as seen from above. They may be prepared as part of the design process, or to provide instructions for construction, often associated with other drawings, schedules, and specifications.
Depending on the size of the building, floor plans are typically drawn at scales of between 1:200 and 1:20. Different line types, colours and weights can be used to differentiate between the types of drawn information they include.
Floor plans can be drawn for whole buildings, a single floor of a building, or just a single room. The more detailed the floor plan is in terms of layout, fittings and so on, the more useful and instructive it will be for the project. However, if spaces are complex, it is normal for separate drawings to be prepared for different trades, such as electrical and lighting drawings, plumbing drawings, and so on.
The lower-right-hand corner of the sheet is typically reserved for a title block. This provides a space to record the name of the project, the name of the drawing, the scale, the originators name, the date, revision history, and so on.
The floor plan view should be roughly centred on the sheet, with the front of the building typically drawn along the lower side of the sheet. A north point may be included to show the orientation of the floor plan.
Typically, the outside walls are drawn first, to lay the plan out on the sheet, then the internal walls, then windows, doors, stairs, lifts, ramps, and so on, are added. An arrow is used to indicate the upward direction of stairs and ramps. It is usual for a faint dotted line to be drawn around stairs (or other openings) where they are open at ceiling level.
Rooms should be clearly labelled, with block lettering in the centre of each room. The correct symbols should be added for elements such as; appliances, fixed furniture, fittings, building services, and so on.
 Related articles on Designing Buildings Wiki
- Block plan.
- Common mistakes on building drawings.
- Decorating a newly built home.
- Drawing projections.
- Electrical drawing.
- General arrangement drawing.
- Manual drafting techniques.
- Residential design and 3D rendering.
- Section drawing.
- Standard hatching styles for drawings.
- Symbols on architectural drawings.
- Techniques for drawing buildings.
- Types of drawings.
- Working drawing.
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