Phase 7 · Pass the examination
Drawings for estimating purposes
What to draw, at what level of finish, and why proportion and dimensions matter more than scale.
Who this is for:Candidates at any stage
Not to scale, but in proportion and dimensioned — enough for someone to price the structure from.
What the drawings section asks
Institution of Structural Engineers
- Prepare drawings and critical details for estimating purposes.
- Drawings do not need to be to scale but should generally be in proportion and should be dimensioned.
- They should include appropriate plans and sections including foundations. Elevations are usually expected for bridges, and should be included for buildings where necessary to convey the scheme.
- It may be appropriate to draw part plans where the structure is symmetrical, or a single plan to represent a number of identical floors.
- Members not treated as principal structural elements may be sized for estimating purposes using engineering judgement, span/depth ratios, or design guides.
- For bridges, cross sections and longitudinal sections provide the most design information; plan views matter for skew bridges.
- Section 2d — drawings and critical details
- 20marksA minimum of three critical details would ordinarily be expected.
- Section 2d — drawings and critical details
- 30marks
From Exam Guidance and Instructions — Chartered Membership Examination, Institution of Structural Engineers.
"For estimating purposes" sets the level of finish
That phrase tells you what is enough. Somebody should be able to take off quantities and price the structure. They do not need construction information.
So: grids, dimensions, member sizes, levels, foundation extents, and the stability system clearly identified. Not: reinforcement detailing, bolt schedules or setting-out to millimetres.
This is liberating under time pressure, and candidates who draw to a construction standard run out of day.
What to draw, in order
- 01A general arrangement plan with grids and dimensions, member sizes marked, and the stability elements clearly distinguished.
- 02A section through the building or bridge showing storey heights or clearances, the frame, and the foundations.
- 03A foundation plan, which candidates forget and which the instructions specifically require.
- 04Elevations where they are needed to convey the scheme — routinely for bridges, selectively for buildings.
- 05The critical details.
Use the shortcuts the instructions permit: a part plan where the structure is symmetrical, one plan representing several identical floors. Say what you are doing — "typical floors 2–5" — so the marker knows it is deliberate.
Proportion is the thing candidates get wrong
Not-to-scale does not mean not-in-proportion. A 6 m span drawn the same length as a 15 m span makes the scheme unreadable and suggests you have not thought about it. Sketch light guidelines first and keep relative lengths honest.
Freehand is acceptable throughout, and the Institution's preparation guidance illustrates freehand sections that carry vertical heights and horizontal dimensions and nothing else. That is the standard: legible, dimensioned, proportionate.
Practical technique
- Practise drawing schemes under time pressure — the preparation guidance recommends exactly this, including practising with coloured pens.
- Different building sizes need different techniques and drawing scales to present clearly in the time available. Work out yours in advance.
- Draw the plan before the section, and take the section from it.
- Label everything. An unlabelled member is a member the marker cannot credit.
- Number your A3 graph paper sheets as instructed so the answer pack stays in order.
The order to draw in
- 01
General arrangement plan
Grids and dimensions, member sizes marked, and the stability elements clearly distinguished from the rest. Use a part plan where the structure is symmetrical, and say that is what you are doing.
- 02
Section
Storey heights or clearances, the frame, and the foundations. Take it from the plan you have just drawn.
- 03
Foundation plan
Specifically required by the instructions, and the one candidates most often omit. Quick, once your column loads are estimated.
- 04
Elevations, where they earn their place
Routinely expected for bridges; for buildings, only where they are needed to convey the scheme.
- 05
The critical details
A minimum of three, selected because your scheme depends on them.
Drawing under time pressure
Worth doing
- Keep relative lengths honest — not to scale still means in proportion
- Dimension everything an estimator would need
- Label every member and every grid
- Use one plan for several identical floors, and say so
- Draw freehand if that is faster for you — it is explicitly acceptable
Avoid
- Draw to construction standard when estimating standard is asked for
- Detail reinforcement or schedule bolts
- Leave the foundation plan until last
- Draw a 6 m span the same length as a 15 m one
- Forget to number the A3 graph paper sheets as instructed
Related pages and tools
- Critical detailsThree at minimum, chosen because they are critical to your scheme — not because they are the ones you can draw.
- Chartered examThe five sections, what each is worth, and what the examiners say they are looking for in each.
- CalculationsWhich elements to design, how far to check each, and how to keep a calculation package legible under time pressure.
- Planning the dayTurning marks into minutes, deciding when to commit to a scheme, and what to do when you fall behind.
- Scheme designWhat makes two schemes genuinely distinct, why viability matters as much as difference, and how to appraise them.