Design Drawing and the Language of Drafting

One drawing, many builders

A design drawing is not a picture of a building. It is a set of instructions, and the people who read it are not the person who drew it. A joiner, a bricklayer, a client and an inspector may all work from the same sheet, in different places and at different times, and the building only comes out right if every one of them reads it to mean the same thing. That is the whole idea behind drafting: a drawing has to mean one thing, not several. So the parts of this topic that look like fussy detail are the opposite. A convention is an agreed way of showing something, so that everyone reads it the same way. A symbol is a small agreed picture that saves writing the same note a hundred times. A scale is a fixed promise that a distance on the paper always stands for a set distance in real life, so anyone can measure the drawing and get the real size back. If a drawing leaves any of that to guesswork, two readers build two different things, and one of them is wrong. Carry one question through everything that follows: could two different people read this drawing the same way and build the same thing?

The words drafting turns on

Five terms, each defined by what it is. They are the grammar of a working drawing.

Tap the two that remove doubt

Tap the TWO choices that make a drawing mean one fixed thing, rather than leaving it to the reader to guess.

• Marking the drawing with a scale, so any length can be measured back to real size
• Using the agreed symbol for a door, which every reader already knows
• Drawing the walls roughly by eye with no sizes given
• Inventing a personal mark for a window that only the author understands

Why the wall came out wrong

A designer sketches a room and hands it over with no scale marked on it. The joiner and the bricklayer each build to the size they assumed, and their walls do not meet. What is the real cause?

• With no scale, nobody could read a real size from the drawing, so two readers assumed two different sizes
• The two builders were careless and should have measured better
• The sketch was not neat or attractive enough
• They used the wrong tools for the job

A picture against a working drawing

Both show a building. Only one of them can be built from without guessing.

Match the symbol to what it means

Two things a scale lets you do

Select the TWO things a stated scale makes possible.

• Read a real length off the drawing by measuring the paper and converting
• Draw a large real building so that it fits sensibly on a sheet of paper
• Make the drawing look more attractive to the client
• Change the real size of the finished building

Reading and writing a drawing

A shape that works on any question about producing or judging a design drawing. State the scale. Without it the drawing states no size at all, so this comes first, not last. Use the agreed symbols and conventions. They exist so a reader who has never met you can still read the sheet correctly. A mark you invent is a mark only you can read. Put the dimensions on. A reader should be able to build the thing without measuring the paper and hoping, so the key sizes are written directly. Label the views. Say which drawing is the view from above and which is a view of a face, because the same room looks completely different from each, and a reader must know which they are looking at. Write success criteria as testable statements. A success criterion is something you can later check as done or not done. A useful one names a measurable outcome. A useless one is a vague wish. Three habits cost marks here. The first is leaving off the scale, which makes every length a guess. The second is inventing a private symbol, which breaks the one thing a drawing is for. The third is writing a success criterion like make it look nice, which cannot be tested and so cannot be evaluated at the end.

Work out the length on paper

A wall is 5 metres long in real life. It is drawn at a scale of 1 to 100. Remember that 5 metres is 5000 millimetres. How long should the wall be on the paper, in millimetres?

Order how a design drawing is made

Put these six steps of producing a design drawing into a sensible order.

• Identify and calculate the information the design needs, such as the sizes to fit
• Write the success criteria the finished design must meet
• Choose a scale that lets the whole thing fit on the sheet
• Draw the plan and the elevations using the agreed conventions
• Add the dimensions and symbols so nothing is left to assume
• Evaluate the drawing against the success criteria

Build the scale rule

This is the rule that lets you use a scale both ways. Assemble it.

Read the drawing

Five questions on the language of a working drawing. Three lives.

One room, shown two ways

Here is an invented example, written for practice. A designer has to show a small store room so that a builder can make it. One drawing is not enough, because a single view leaves out what a builder needs to know. The first drawing looks at the room as if you were a bird hovering directly over it, with the roof taken off. From up there you can see the shape of the room, where the walls run, and where the door and the one window sit. What you cannot tell from above is how tall anything is. The second drawing stands you in front of one wall and shows just that face, straight on. Now you can see how high the wall is, how tall the door is, and where the top of the window sits. What this second view leaves out is the overall layout you saw from above. Both drawings are made at the same fixed ratio of paper size to real size, so a length measured on one matches a length measured on the other. The door is shown by the same agreed arc on both, so nobody has to be told what it is. Between the two views, and with the sizes written on, a builder has everything needed and nothing left to assume. That is the point of drawing a thing more than one way: each view answers a question the other cannot.

Complete the drafting facts

The view looking straight down from above, showing the layout, is the _____. The view of one vertical face seen straight on, showing height, is the _____. The fixed ratio between a paper distance and the real distance it stands for is the _____. An agreed way of showing something so that everyone reads it the same way is a _____.

Three drawings to fix

Three student design drawings come back with a problem. The idea in each is fine; the drawing lets it down.

• A student hands in a neat, well drawn plan with no scale marked anywhere. Why can the builder not use it?
• A student invents a neat little picture of their own to mark a radiator, instead of using the agreed symbol. What is the weakness?
• A student writes their only success criterion as the design should look good. Why will that criterion fail them at the evaluation?

Explain why a drawing needs conventions

A friend is good at drawing buildings but keeps losing marks on the design work, because their drawings are hard for anyone else to build from. Explain what a working drawing is really for, and what it must include.

• Explain the one idea a working drawing rests on, that it must mean the same thing to everyone who reads it
• Explain what a scale is and why a drawing without one states no real size
• Explain why agreed symbols and conventions matter more than an attractive personal style
• Explain the difference between a plan and an elevation, and why a builder often needs both
• Explain what makes a success criterion useful rather than a vague wish
• Finish by describing how you would check a finished drawing before handing it over