MacLeamy Curve

The MacLeamy curve is a diagram showing that a project team’s ability to influence cost and performance is highest at the start of design and falls toward construction, while the cost of making a design change rises over the same period.

The curve is a conceptual picture, not a cost formula. Its point is timing: decisions that shape how a building works are cheapest while it is still a concept, and expensive once they are drawn into construction documents, bid, built and occupied. Architects and builders use it to justify moving design effort, and the people with the most specialized knowledge, earlier in the process.

Try it

When does the operator join?

Slide the parking operator’s arrival across the project phases and see which garage decisions are still open.

If the operator joins at concept, nearly every decision is still open. At construction, only signs, staffing, procedures and pricing remain, and every other change is rework.

Phases at which each decision becomes fixed are typical, not universal.

In parking

Driveway locations, ramp layout, column grid, clear heights, island locations and conduit routes are all fixed early, and all of them decide how a garage operates for decades. Yet the operator is often invited in at the far right of the curve, after the building is finished, when the job is to make it work. Bringing an owner’s parking consultant in at feasibility moves that knowledge to the cheap end of the curve.

The Parkonomics view

Every operating problem a garage has was once a cheap decision on a drawing. The curve is the simplest argument for paying for operational review early, and for writing operating requirements into design contracts and design-build criteria before the design is locked.

Related terms: Integrated Project Delivery, Progressive Design-Build, Bridging Documents, First Cost, Life Cycle Cost, Functional Design Review

Further reading: Designed to Park, or Designed to Impress?