Construction manager at risk (CM at risk, or CMAR) is a delivery method, common in North America, in which the owner hires a construction manager while the design is still being developed. The construction manager first advises on cost, sequence and buildability; then, once the design is far enough along, agrees a guaranteed maximum price (GMP) and takes on the risk of delivering the work within it, usually by letting trade packages.
At a glance
| Contracts | Owner with designer; owner with construction manager (two separate contracts) |
| Phases | Preconstruction services, then construction under a GMP |
| Price | Guaranteed maximum price, often with shared savings |
| Similar to | Early contractor involvement and two-stage tendering in the UK |
| BIM role | Model-based estimates, constructability reviews and 4D during design |
The parts
- Preconstruction services: cost plans, programme, constructability and phasing advice during design.
- GMP proposal: the construction manager's price, based on the design documents at an agreed stage, with allowances and contingency.
- Trade packages: the work let to trade contractors, often by open tender.
- Open book: costs are visible to the owner; savings below the GMP may be shared.
How it is used on projects
The construction manager's early involvement is where BIM pays off: quantities from the design model support each cost plan, 4D sequences test phasing, and constructability reviews in the model find problems while they are still cheap to fix. The GMP is usually set from a design that is not yet complete, so the model at that milestone and its stated level of information need matter: what is not in the model at GMP becomes an allowance or a later change.
Variations
- CM agency (CM as adviser): the construction manager advises but does not take the price risk.
- Two-stage design and build in the UK and early contractor involvement in Australia work in a similar way.
- Progressive design-build gives one party both design and construction, with a price set part-way through.
Common misunderstandings
- "GMP means the price can't change." Owner changes in scope still change the price; the GMP covers the agreed scope.
- "Preconstruction is free." It is usually paid as a separate fee.
- "The construction manager owns the design." Design responsibility stays with the designers.
Where to read more
The Construction Management Association of America (CMAA) and the AGC's published guides to project delivery methods; the IPD entry; the lessons on quantities and cost of change on this site.