Different elements of a building are represented by designated symbols on a plan. These tend to remain consistent from one plan to another, so the more plans you look at, the more confident you will become with recognising what each symbol represents. If you are shown a plan and you are not sure what something means, simply ask for clarification – the architect or developer will be happy to assist.

Identifying each drawing

Every building project will require a number of drawings. Each drawing is given a unique reference number, which is usually found in the table at the bottom right of each drawing. During the design process, as drawings are gradually revised, they are given a new reference number. There is sometimes a table provided that briefly describes any revisions that have been made to the drawing.

Key advice for access groups: when you make comments on a drawing, note the drawing number and revision, and keep a copy of it with your report for future reference.

Scale

Plans are usually drawn to a scale to help the user gain a grasp of the size of the planned space. The scale is the ratio between the dimensions as represented on paper and the actual existing or intended dimension. It is usually indicated in the title box of the drawing.

The choice of scale depends on the size and nature of the project, the stage it has reached, and the amount of information to be shown on the drawing. For example:

• outline plans for a larger project might be at a scale of 1:200 or 1:100
• a house, or intricate parts of a large building, might be drawn to 1:50 or 1:20

If a plan is drawn at a scale of 1:50, it means that every one ‘unit of measurement’ on the plan represents 50 units of the same measurement in the real world – for example, each centimetre on the plan will be 50cm (or 0.5m) in reality. Therefore beware: if plans are enlarged or reduced in size using a photocopier, the scale will no longer be correct.

Dimensions are very occasionally added to a drawing to suit its specific purpose or the stage reached in the project. However, dimensions will rarely be available for purposes of checking corridor widths or door openings, in which case you will have to refer to the scale.

A scale rule is used to make it easier to convert plan measurements into 'real life' dimension. Scale rules are usually double sided, giving them four edges, each with one or two scales. Scale rules allow the user to instantly see what dimension a feature on the plan represents without having to convert it.