Case Study

Question 1

What is the most efficient Plan?

Answer 1

In terms of cost a simple square or rectangle is the most efficient.

A circular plan is the most efficient in terms of wall/floor ratio, however the difficult shape impacts upon internals making it less efficient.

Question 2

What other design efficiency’s are you aware of?

Answer 2

Net Internal Area - total usable floor area excluding toilets, corridors, stairs ,etc.

Question 3

What traditional construction methods did you base your cost model of?

Answer 3

Pad foundations in a grid format.
Strip foundations to the perimeter.
Ground bearing slab
Steel frame based upon 60kg/m2
Composite metal deck - Upper floor
Kingspan cladding to roof
External walls - Masonry and cladding
Glazing assumed at 15% of facade

Question 4

What is the difference between a CAT A fit out and a CAT B fit out?

Answer 4

Cat A fit out is a developers fit out and creates basic functionality so this will include RAFs, Suspended ceiling, carpet tiles, power supplies, etc.

Cat B fit out is a tenants fit out which is bespoke to them so this will usually include working with interior designers, this includes furniture, internal partitions, etc.

Question 5

What factors should be considered when choosing between a CAT A and Cat B fit out?

Answer 5

Lease Terms
Budgets
Tenant Requirements

Question 6

What does the wall to floor ratio tell me?

Answer 6

It tells you the amount of wall area in comparison to floor area, the closer the formula is to 0.40 is deemed very efficient.
If it is high and inefficient this shows the additional costs facade costs and potentially foundation costs, etc.

Question 7

Why does an irregular building shape create inefficiency’s?

Answer 7

This is due to the increased building perimeter and design complexities.

Question 8

What makes the two Storey design more efficient?

Answer 8

Reduced overall building footprint
Costs for the roof and foundations are not duplicated
Utilities can be designed more efficiently

Question 9

What was the clients main requirements on this site?

Answer 9

Parking Provisions
Cost - Cost limit

Question 10

What are the benefits and disadvantages of a steel frame?

Answer 10

Advantages - quick erection on site, long spans, sustainability benefits, lightweight (reduces foundations requirements), manufactured offsite.

Disadvantages - Maintenance, additional fire protection, large items to be transported, volatile costs.

Question 11

What is asbestos?

Answer 11

Asbestos is made up of fibrous minerals that is harmful to humans, causing lung cancer, asbestos was used due to it being heat and corrosion resistant.

Question 12

What was the cost model you used?

Answer 12

The cost model followed an elemental cost plan format with a number of assumptions.

Foundations - Strip to perimeter, Pads on a 7.5m x7.5m grid to the perimeter grid, central spine of a hit and miss basis.

Steel - single storey based upon 40kg/m2, two storey based upon 60kg/m2

Upper floor - Composite concrete metal deck

Roof - Kingspan cladding

External walls - built up cladding and masonry/timber cladding

Glazing - based upon a percentage.

Office fit out was based upon a cost per m2 rate

Question 13

How did you advise the client on reducing the risk of the site?

Question 14

What did the ground conditions report tell you and what impact can this have on costs?

Question 15

What was the main challenge you faced when advising on the design options?

Question 16

What were the key cost drivers across the three options?

Question 17

How did site constraints influence your recommendations?

Question 17

Why was cost per m² such an important metric in this case?

Question 17

How did you ensure your feasibility advice aligned with the client’s priorities?

Question 18

Talk me through how you prepared your Order of Cost Estimates.

Question 19

What assumptions did you make in your elemental cost model?

Answer 19

assumptions made were based upon discussions with the architect and the engineers.

Eaves height
Foundation types and locations
Steel tonnage
% of glazing

Question 19

How did you validate the accuracy of your cost model at feasibility stage?

Answer 19

To validate the accuracy of the cost model i compared the cost per m2 against benchmark data.

The two contractors taken forward - HQ tender return worked out £3029m2 - £3319m2.

Question 20

How did you explain the difference between overall cost and cost per m² to the client?

Answer 20

Cost per m2 (The Benchmark): I explained in the early design stage to get a rough idea of budget feasibility. It represents the average cost for basic construction but often misses specific site conditions, high-end finishes, or professional fees.

The overall cost is the total amount, and what the likely sum will be paid to complete the project.

Question 21

What risks are associated with cost modelling at early design stages?

Answer 21

Low level of information
Scope creep
Assumptions

Question 22

How did wall‑to‑floor ratios influence your advice?

Question 23

What does a “highly efficient” wall‑to‑floor ratio look like, and why?

Answer 23

Calculates external wall area divided by gross internal floor area - 0.4/0.5 is considered efficient for commercial residential. Warehouses/industrial - 0.2/0.35 (lower

Question 24

How did you balance design efficiency with client preferences?

Question 25

Why were Options 1 and 3 less efficient than the ideal ratio?

Question 25

How did you explain the impact of floor‑to‑ceiling heights on cost?

Question 26

Why was Option 1 initially attractive to the client?

Question 26

What would have been the implications of selecting Option 1 instead of Option 3?

Question 26

How did you justify Option 3’s higher initial cost?

Question 26

What were the main disadvantages of Option 1?

Question 27

Why did Option 2 have such a high cost per m²?

Question 27

How did you explain duplicated elements (roof, foundations) to the client?

Question 28

What made Option 2 unviable from a site‑planning perspective?

Question 28

How did you ensure the client understood the long‑term implications of each option?

Question 28

How did you manage the client’s concerns about cost differences?

Question 29

Why did Option 3 ultimately represent the best value for money?

Question 30

How did you present your findings to the client?

Question 31

What techniques did you use to support informed decision‑making?

Question 32

How did you handle the client’s queries about ratios and efficiency?

Question 33

How did you mitigate the risk of future design changes?

Question 33

What were the main risks associated with selecting the wrong design option?

Question 34

How did you ensure the chosen option supported future flexibility?

Question 34

What triggered the need to revisit the OPW as a potential depot?

Question 35

How did the change in client representatives affect the project?

Question 36

How did the government funding deadline influence your procurement advice?

Question 37

What were the implications of splitting the HQ and OPW into two contracts?

Question 38

What procurement routes did you consider and why?

Question 39

Why did you ultimately reject Design & Build?

Question 40

What were the advantages of Design & Build for this project?

Question 41

What were the advantages of the Traditional route?

Question 41

How did you assess whether the client could manage those risks?

Question 42

What risks did the client retain under the Traditional route?

Question 43

Why was the JCT 2024 Intermediate Building Contract appropriate?

Question 44

How did the project value influence your contract recommendation?

Question 45

How did you decide which elements should be contractor‑designed?

Question 45

What factors made the OPW scheme suitable for an Intermediate contract?

Question 46

Why did you recommend using Contractor’s Design Portions?

Question 47

What risks were transferred to the contractor through these portions?

Question 48

How did you explain the implications of design portions to the client?

Question 49

How did procurement choice affect the ability to meet the March 2026 deadline?

Question 49

What would have been the consequences of missing the funding deadline?

Question 50

How did you ensure the procurement route supported timely delivery?

Question 51

How did you manage the client’s concerns about cost certainty?

Question 52

How did you explain the trade‑off between cost premiums and risk transfer?

Question 52

How did you maintain trust during the change in client representatives?

Question 53

How did you ensure the client understood the procurement implications?

Question 54

What did you learn from managing procurement on this project?

Question 55

What would you do differently if faced with the same situation again?

Question 56

How has this experience improved your ability to advise on procurement?

Question 57

How did this issue help you develop your professional judgement?

Question 58

Did the size of the building meet the clients requirements for the office/workshop space?

Question 59

Did the irregular shape impact upon the cost model?

Answer 59

Engineer advised steel frame to be based upon 60kgm2 compared to

Question 60

What do you mean by repeated components?

Answer 60

The reduced building footprint reduced the roof and foundation costs as the total area was smaller. Noting discussions with the engineer around the foundations they suggested the increase would not be significant.

Question 61

What height would need to achieve to get the wall to floor ratio of 0.4-0.5?

Question 62

What is Net Zero?

Answer 62

Highly efficient structure that produces as much renewable energy on site as it consumes annually, resulting in zero operational carbon emissions. Effciency - minimise energy demand through airtight construction and efficient insulation. Renewable energy - on site tech such as solar panels

Question 63

What impact did sustainability have on costs and your reporting to the client?

Question 64

How did you value the sustainability provisional allowance at the early stages?

Answer 64

I had conversations with the design team to understand the requirements. As details were limited i included a provisional allowance of 5% of the actual build cost.

Question 65

How does net zero work and how does it impact upon costs?