Team Site management

Kytom design and build: 18% time saved, 4 trade-offs that decide everything

Four contractual trade-offs that decide the schedule gain

Design & Build only performs above 300 sqm and when the brief remains technically open: outside this window, it costs more than a conventional project management setup. On our recent operations, integrating design and build significantly shortens the schedule compared with a separate-package approach. This single contract appeals to real estate departments, but it only delivers on its promises if four contractual trade-offs are set from signature: integration scope, level of definition at order, validation milestones, risk allocation. Kytom, founded in 2006, has deployed this method across 1200+ office projects in France and Spain: at comparable scope, a well-framed project unfolds in a completely different way from a poorly arbitrated one.

The success of a Design & Build project rests on four contractual decisions made before studies begin.

Integration scope. Integrating architectural project management and execution without including plumbing, HVAC or low-current studies in the same contract reproduces the breaks of conventional project management. Kytom recommends a scope covering at least architecture, finishing works and the main technical packages.
Level of definition at order. A descriptive specification beyond 70% technical definition cancels out co-design. Conversely, too thin a brief, below 30%, lets the budget drift for lack of a stabilised programme. The operational window lies between 40% and 60% functional definition, without means-based prescriptions.
Validation milestones. Three contractual validations, framing, detailed design, pre-execution, are enough. Beyond five milestones, the process fragments and loses its schedule gains.
Risk allocation. The full transfer of contingencies to the contractor is paid for in the price: the contractor provisions for the uncertainty it bears alone. A negotiated sharing of soil, existing-structure and client-interface risks remains more efficient.

Our reading differs from the profession’s dominant discourse on one precise point: the Design & Build orthodoxy promises an almost systematic gain. In practice, on the operations we manage, this gain disappears as soon as one of the four trade-offs is poorly set. A conventional project management setup executed rigorously is better than a poorly framed Design & Build.

When these trade-offs are not enough. Design & Build, even well framed, remains counterproductive on operations below 300 sqm (contractual structure costs disproportionate to the gain), on projects where more than 40% of the budget depends on prior geotechnical or asbestos-removal studies, and on programmes requiring a heavy administrative authorisation file before signature. In these cases, conventional project management with a general contractor in a single package delivers a better cost/time/risk ratio.

From what project size does Design & Build become relevant?

Above 300 sqm of office space. Below that, contractual structure costs (1.5% to 2.5% of the works budget) absorb the schedule gain. The break-even point lies between 280 and 320 sqm depending on technical complexity.

What level of technical definition in the brief for a high-performing Design & Build?

Aim for a functional brief without means-based prescriptions, below 70% technical definition: beyond that, the contractor no longer has room to propose technical variants. Conversely, too thin a brief exposes the project to budget drifts that are hard to control. The window is calibrated according to complexity, on projects above 300 sqm.