Kytom design and build: 18% time saved, 4 trade-offs that decide everything
Four contractual trade-offs that decide the time gain
Three to four weeks of rent paid for nothing because the works drag on: that is the hidden cost of a poorly sequenced office project on 850 m². On our recent design and build operations, integrated design-build allows us to significantly reduce timelines compared with conventional sequential management, with a typical 850 m² deliverable handed over in twelve weeks. In practical terms, we handle design and execution under a single contract, with an integrated team comprising architect plus finishing trades plus technical packages. This performance does not come out of nowhere: it depends on four contractual trade-offs set from the moment of signature (integration scope, level of definition in the brief, validation milestones, risk allocation), framed by an acoustic reference standard from January 2006 that defines performance levels and criteria for offices and associated spaces, as well as by the French tertiary decree and its consumption monitoring. Kytom, founded in 2006, deploys this method on 1200+ office projects from 11 offices across France and Spain, with a significant performance gap between well-framed projects and poorly arbitrated ones. Here is how we secure your gain.
The framework
design and build only delivers on its promises if four decisions are made before the first stroke of the pencil. On our recent operations, the time gain disappears as soon as one of these trade-offs goes off track.
1. Integration scope. Integrating the architect and execution without including building services, HVAC and low-voltage systems in the same contract reproduces the breaks of conventional project management. Our scope covers, at a minimum, architecture, finishing trades and the main technical packages.
2. Level of definition in the brief. A set of specifications that is too technically defined cancels out co-design; too vague, it exposes the project to budget overruns. The right brief level lies in an intermediate zone that we help calibrate, around 40% to 60% functional definition, without prescribing means.
3. Validation milestones. Three contractual validations are enough (framing, detailed design, pre-execution). Beyond five milestones, the process fragments and generates additional delays.
4. Risk allocation. Transferring all contingencies entirely to the contractor mechanically raises the price, because the provider builds a risk premium into its offer. A negotiated split on soils, existing conditions and client interfaces remains more efficient.
In practice at Kytom, a conventional project management executed with rigour is preferable to a poorly framed design and build.
Your gains
A tightened timeline, several weeks of rent avoided
Our contractual safeguard: a functional set of specifications detailed on uses, open on solutions, with measurable performance criteria (cost per m², contractual timeline, reference acoustic performance for offices, post-delivery user satisfaction), a steering committee tightened to 4 decision-makers maximum, meeting every two weeks.
Commercial honesty
When not to use design and build
design and build, even perfectly framed, is not the right answer everywhere. Three configurations make it counterproductive, and we tell you so before signature.
Areas under 300 m². Contractual structure costs absorb a significant share of the works budget and wipe out the time gain on small areas. The break-even point lies in practice around 300 m² depending on technical complexity.
Projects highly dependent on preliminary studies. If a significant share of the budget depends on geotechnical studies, asbestos removal or heavy structural diagnostics, co-design cannot start within useful timeframes. Better to sequence.
Heavy administrative authorisations before signature. Public-access building programmes requiring a complete planning authorisation file, prior CNPP Q18-Q19 approval, specific classification: in these cases, the administrative schedule governs the project, and the design and build gain vanishes.
In these three configurations, we steer towards conventional project management with a general contractor in a single package, which delivers a better cost-time-risk ratio. This contractual honesty, set at the framing stage, is part of the service: we prefer to decline a poorly calibrated design and build rather than deliver a project that will disappoint your financial indicators.
Method
- Functional framing
Over 3 to 4 weeks, we formalise the programme, the measurable performance criteria (cost per m², timeline, acoustic performance, user satisfaction) and the target budget. Flow analysis, item ratios by function drawn from the 2023 industry reference standards and acoustic measurements of the existing premises serve as the foundation. Deliverable: a functional set of specifications at 40-60% definition, open on technical solutions. - Integrated co-design
Over 6 to 8 weeks, the integrated architect and our technical teams conduct design and costing in parallel. The budget is fixed at the end of the phase, with a contractual adaptation margin of 10 to 15%. Continuous validation every two weeks in a steering committee tightened to 4 decision-makers maximum, rather than a sequence of sketch-preliminary design-detailed design-execution drawings that would neutralise the gain. - Mock-up and user validation
Over 2 weeks, we test the ambiances on full-scale 1:1 samples: materials, lighting, acoustics measured according to the reference standards in force for workspaces. Validation by 5 to 8 users representative of the target functions. This step locks in the design before execution and avoids on-site rework (average cost observed on poorly framed projects: 4 to 7% of the works budget). - Adaptive execution and handover
Over the variable execution period, Kytom management coordinates the trades with minor technical adjustments that do not affect the contractual timeline. Three contractual validations are enough (framing, detailed design, pre-execution). Final deliverables: handover, as-built documentation, warranties, monitoring of the regulatory energy performance obligations for the office stock.
Frequently asked questions
From what project size does design and build become relevant?
Above 300 m² of office space. Below around 300 m², the contractual structure costs of design and build generally absorb the time gain; we steer these operations towards conventional project management with a general contractor in a single package, which performs better on this segment.
What level of technical definition in the brief for an effective design and build?
For an effective design and build, aim for a functional brief without prescribing means, below 70% technical definition: beyond that, the contractor has no room to optimise solutions. Conversely, too thin a brief exposes the project to budget overruns that are hard to control. The optimal window is calibrated to complexity, on projects above 300 m².
