|£2bn - the cost of rework every year|
When specification-based disputes go to court - the reasons as a percentage are:
- ‘Or equal’ specifications: 25%.
Jobs have ground to a halt over arguments about just what is ‘equal’ to the proprietary specification, and whose decision this is.
- Conflict between drawings and specifications: 12%.
Remains a major issue.
- Ambiguity: 12%
- Defective specifications, e.g. buildability: 12%.
- Inaccurate technical data: 12%.
- Product performance deficiencies: 8%
Looking at various surveys across the world...
- http://ascelibrary.org/action/showAbstract?page=76&volume=18&issue=2&journalCode=jmenea shows rework costs 4.4% of construction costs and takes 7.1% of time, in Sweden
- http://dspace.brunel.ac.uk/bitstream/2438/1730/1/01347434.pdf rework costs of 5% in Australia, for example – range is 3% to 23% of contract value overall.
- http://www.constructingexcellence.org.uk/pdf/rethinking%20construction/rethinking_construction_report.pdf - the key UK document I think, for targets for improvement – Egan said up to 30% of construction cost is down to rework in the UK
- http://www.civil.hku.hk/cicid/3_events/48/papers/5.pdf quotes 10% of cost on rework – see Table 1
Thanks to NBS Technical Author John Gelder for many of these statistics and the original articles on the NBS Educator site.