McLaren was appointed architect by Abercromby for the design and supervision of the construction of four car dealership showrooms and workshops.
Disputes arose between the parties relating to the level of McLaren's fee and a claim by Abercromby alleging that McLaren was negligent in the design of the heating system for the showrooms and workshops.
In accordance with McLaren's design, underfloor heating was installed in both the workshops and showrooms, but Abercromby maintained that it failed to adequately heat the premises during the winter. Accordingly, Abercromby replaced the entire system with a gas-fired system. McLaren accepted that it was at fault in the design of the heating system, but argued that replacing the system was an unreasonable and disproportionate response to the failings in the original system.
McLaren argued that it was unreasonable for Abercromby to have entirely replaced the negligently designed system and contented that the cost of reinstatement was therefore unreasonably incurred and was not recoverable.