Phase 7 · Pass the examination
Producing distinct, viable schemes
What makes two schemes genuinely distinct, why viability matters as much as difference, and how to appraise them.
Who this is for:Chartered Member candidates ·IMIStructE members moving to MIStructE ·Incorporated-Member candidates
Two schemes that differ in one respect are one scheme drawn twice — and the marks for the appraisal depend on having made them properly different in the first place.
What makes solutions distinct
Institution of Structural Engineers
- Significant differences may include, but are not limited to: stability (shear walls, cross-bracing, sway frames, monolithic RC frames); framing (column spacing and span layout, precast, in-situ); foundations (piled, pad, strip, raft, ground improvement; ground-bearing versus suspended slabs); materials (concrete, steel, masonry, timber); load path; and construction method (precast, modular, off-site, segmental).
- Changing just one of these would not be enough to make a solution distinct.
- Higher marks go to candidates providing as many significant differences as possible, while demonstrating the viability of both.
- For the bridge question, each scheme should be a different form of bridge structure with different spans and/or different load paths to the foundations. Changing only the material is not enough.
- Sketches may be freehand and need not be to scale, but must clearly convey the design principles.
- Candidates should demonstrate approaches that minimise the use of material through structural efficiency, and take advantage of any reuse opportunity offered in the question.
- Sustainability in every question
- From January 2024The Institution altered the exam content so that sustainability is a key feature of all questions. Only documents carrying '2024' in the version number describe the current paper.
- Unsafe structure or ignored stability
- Automatic failStated identically in the Chartered, Incorporated and supplementary instructions.
From Exam Guidance and Instructions — Chartered Membership Examination, Institution of Structural Engineers.
Difference and viability pull against each other
The instruction is to make the schemes as different as possible while demonstrating that both are viable. Those two demands are in tension, and the resolution is not to compromise on either but to choose your ground carefully.
The examiners warn specifically against going too far: proposing something clearly impractical so that it is easy to dismiss in the appraisal. That is a straw man, and it costs marks twice — once for a non-viable scheme, and once for an appraisal that had nothing real to weigh.
The practical target is two schemes you could defend to a client. Then the appraisal becomes a genuine engineering judgement rather than a formality.
A method that produces distinct schemes reliably
Work down the list of difference categories deliberately rather than designing twice and hoping.
- 01Read the brief for the constraint that dominates. Span? Ground conditions? Programme? Access? Reuse of an existing structure? That constraint should drive scheme A.
- 02Design scheme A around it, and note the stability system, framing, foundations, material, load path and construction method.
- 03Design scheme B by deliberately changing three or four of those six. Not one. If changing them breaks viability, you have learned something about the problem that belongs in the appraisal.
- 04Sketch the stability of both before going further. Stability failure is an automatic fail, so it is the one thing to settle first.
- 05Check both against the brief's constraints. If either fails one, fix it now.
The appraisal
The instruction is to review and critically appraise and to identify the solution you recommend, giving reasons. It implies discussion of the relative merits of each option, and it requires more than a list of scheme elements with a tick or a cross against each.
Choose criteria that matter for the brief in front of you. A remote or inaccessible site makes availability of materials and skilled labour decisive; an art gallery makes aesthetics matter more than it would in a warehouse. Sustainability must be one of your criteria.
Aspects worth weighing, when they are relevant:
- Economics — structural efficiency, and the knock-on cost effects. A flat slab may not be the cheapest frame but can simplify service routing in a heavily serviced building, or reduce storey height and cladding area in a tall one.
- Programme — speed, but also construction sequence and any restrictions such as outages.
- Construction and demolition — safety during construction, specialist skills or equipment, extensive temporary works, and end-of-life dismantling. Post-tensioned structures are harder to take apart.
- Location — whether the setting rules out materials or techniques, and how hard transport is.
- Maintenance — whether one scheme can be maintained more easily or more safely.
Then finish with a clear recommendation. An appraisal that does not recommend has not answered the question.
In section 1a
Worth doing
- Change three or four of the six difference categories between schemes
- Sketch and label the stability system for both schemes explicitly
- Keep both schemes genuinely buildable
- Choose appraisal criteria from this brief, not from a generic list
- Make sustainability a real criterion, with a reason attached
Avoid
- Present the same frame in two materials and call them distinct
- Propose an obviously impractical scheme to knock down
- Leave stability implicit anywhere
- Produce a tick-and-cross table instead of an appraisal
- Forget to state which scheme you recommend
A method that produces distinct schemes
- 01
Find the constraint that dominates the brief
Span, ground conditions, programme, access, or an existing structure to reuse. It should drive your first scheme rather than being accommodated afterwards.
- 02
Design scheme A around it
Then write down its stability system, framing and grid, foundation type, material, load path and construction method — the six categories the instructions use.
- 03
Change three or four of the six for scheme B
Not one. If changing them breaks viability, that is a finding about the problem, and it belongs in your appraisal.
- 04
Sketch the stability of both, explicitly
Ignoring stability is an automatic fail, so settle it before spending time anywhere else.
- 05
Check both against the brief's stated constraints
A scheme that breaches a constraint the question told you to maintain is not viable, however elegant it is.
Related pages and tools
- Chartered examThe five sections, what each is worth, and what the examiners say they are looking for in each.
- AppraisalWeighing two schemes against criteria drawn from the brief, with sustainability as a key criterion.
- Embodied carbonThe A1–A3 calculation the Institution asks for, where it appears in each paper, and how much depth is expected.
- DrawingsWhat to draw, at what level of finish, and why proportion and dimensions matter more than scale.
- Planning the dayTurning marks into minutes, deciding when to commit to a scheme, and what to do when you fall behind.