What is meant by ‘Design Life’?
We frequently come across contracts that set out particular requirements in relation to the “design life” of building parts.
What “design life” means will depend on the particular facts and terms of each contract. However, the judge in a recent case made some useful observations, which, in the absence of clear definitions, may assist in determining whether design life obligations have been complied with.
Blackpool Borough Council v Volkerfitzpatrick  EWHC 387 (TCC)
Blackpool Council appointed Volkerfitzpatrick under an NEC3 form of contract (with amendments) to design and build a new tram depot as part of a major upgrade to the long-running Blackpool tramway system.
Soon after the works were completed and brought into operation, the new depot suffered from corrosion to the wall cladding panels. Blackpool Council claimed that corrosion so soon after installation amounted to Volkerfitzpatrick being in breach of its obligations to design the works to achieve the contractually specified design life.
In determining the meaning of ‘design life’, the Technology and Construction Court (TCC) looked at two British Standards, which it summarised as follows:
1. BS ISO 15686-1:2000 - entitled “buildings and constructed assets - service life planning”
This contains a definition of design life as the service life intended by the designer. In turn the service life is defined as the period of time after installation during which a building or its parts meets or exceeds the performance requirements.
A performance requirement is defined as a minimum acceptable level of a critical property. There is also a definition of durability as the capability of a building or its parts to perform its required function over a specified period of time under the influence of the agents anticipated in service.
2. BS EN 1990:2002 - entitled “basis of structural design”
Paragraph 188.8.131.52 contains a reference to “design working life”, which means the “assumed period for which a structure or part of it is to be used for its intended purpose with anticipated maintenance but without major repair being necessary”.
Maintenance is defined in the same standard as being the “set of activities performed during the working life of the structure in order to enable it to fulfil the requirements for reliability”.
The court decides
The TCC also took into account a contractual requirement that any required maintenance of the works should not include anything which is ‘non-standard’ or ‘unusually onerous’.
Bearing these in mind, the TCC held that for the wall cladding panels to meet the design life obligation, they would have to be cleaned ‘frequently and intensively, but that cleaning would not be regarded as “anticipated maintenance” for design life purposes as it would not be either ‘standard’ or ‘non-onerous’.
Furthermore, whilst no asset can be expected to perform throughout its entire design life without any maintenance at all, the key distinction is between “anticipated maintenance” and “major repair”. Whilst some routine maintenance is expected, an asset should not require major repair during its design life. What exactly constitutes “major repair” was determined to be a matter of “fact and degree in any given case”.
In the future, parties to construction contracts with design obligations should note that ‘design life’ may equate to ‘lifetime to first major repair’, even though the judge did not go so far as to approve such a definition in this case. The best approach is to clearly define what design life means.