The result is a board approval at RIBA Stage 2 based on a number that bears limited resemblance to the out-turn cost. By the time the real figure surfaces, commitment is too deep to reverse and the conversation becomes about finding savings rather than making a genuine decision.

How do you build genuine contingency and risk allowance into a business case without the number being rejected by Finance as too conservative? What's your methodology for getting to a defensible estimate early?

Couple of links below for those who want to read more on topic. Spoiler alert, out of the six categories of factors that determine whether a conceptual cost estimate is reliable before a spade hits the ground, Bozorgmehr Nia, Taheri and Jamalpour 2023 study's most striking finding: time allocated to the estimate is rated by practitioners as the single most influential factor of all twenty categories assessed.

(50) Achieving Realistic Cost Estimates in Building Construction Projects: A Reliability Assessment of Pre-Construction Stage Cost Estimates

Impact of Optimism Bias Regarding Organizational Dynamics on Project Planning and Control | Journal of Construction Engineering and Management | Vol 137, No 2

The Lean Construction (LC) approach has been described as a practical collection of theories, principles, strategies, techniques, and ways of thinking that together enhance project teams and individuals to improve work processes and produce better value (Mossman 2018).

I have been doing a deep dive into lean construction methodology to assess how applicable it is to a large office fit-out context where we are the client, not the contractor and where our ability to influence how the delivery team operates is real but not unlimited.

The core lean construction methodology promises a fundamentally different delivery experience and is built collaborative planning exercises, detailed project definition with robust, integrated planning, procurement and project delivery.

I am acutely aware that reading about lean construction and doing it on a client fit-out with a demanding internal client are very different propositions.

Question for the community: Has anyone successfully introduced LC discipline on a fit-out project where the main contractor was not already a lean practitioner?

How did you position it; as a client requirement, a collaborative suggestion or something else entirely?

Genuinely hear from peers who have been here before.

For those interested to read more I have copied a few links below -

What is Lean in Business? | Lean Enterprise Academy

Lean Construction Blog by the Experts at TheLeanBuilder.com

Lean Construction Blog

https://4bt.us/simple-guide-to-lean-construction/