The three common delivery models for building projects compared on responsibility, price certainty, speed, change management and the technical capacity the employer must keep in-house.
Most disputes on building projects are not caused by bad workmanship. They are caused by a delivery model that never matched the way the employer actually wanted to work. Choosing the model is therefore a decision about your own organisation as much as about the building: how much technical capacity you intend to keep on your side of the table, how firm the design is at signature, and how much of the risk you want priced into the contract sum rather than carried yourself.
Three models cover most projects.
Under a turnkey contract you agree an outcome — a finished, functioning building — with a single company that carries design, procurement, construction, testing and handover. You receive the key.
Responsibility. Single point. If the roof leaks, there is no argument between designer and builder about whose detail failed.
Price. Usually a lump sum agreed before construction, which means the contractor has priced the unknowns. That price includes a risk margin; you are paying for certainty.
Speed. Generally the fastest of the three, because design and procurement overlap with construction and no interface has to be negotiated between separate firms.
Changes. The weak point. Because the contractor priced a defined scope, employer-driven changes are re-priced from a position of little competition. Turnkey rewards employers who know what they want at signature.
What you need in-house. Comparatively little — an employer's representative to check quality and progress against an unambiguous specification. But the specification itself must be written well, because it is the whole contract.
Turnkey suits investors, institutional employers and clients building abroad who want a fixed outcome on a fixed date, and who are willing to freeze the brief early.
Design-build resembles turnkey but keeps the design conversation open. The contractor is appointed on a concept or a performance brief and develops the detailed design with you as construction proceeds.
Responsibility. Still largely single point, but the boundary between "our design developed your idea" and "you changed your mind" needs to be written carefully.
Price. Often a target cost, a guaranteed maximum price, or a two-stage arrangement where an initial fee covers design development and the construction sum is fixed once the design is far enough along.
Speed. Faster than fully sequential procurement, because early packages start while later design continues.
Changes. Handled far better than under turnkey, provided a formal change control procedure exists from day one.
What you need in-house. A decision-maker with authority and availability. Design-build stalls when the employer cannot answer questions quickly.
Design-build suits projects where the brief is still maturing — hotels, mixed-use developments, campuses — and employers who want to influence the design without carrying construction risk.
Here you appoint a designer directly and a construction manager who plans, tenders and supervises the work packages. Trade contracts may sit with you or with the manager.
Responsibility. Distributed. You hold the design risk; the manager holds coordination; each trade holds its own workmanship.
Price. Transparent — you see each package price — but the total is not known until the last package is let. Cost certainty comes late.
Speed. Packages can start very early, so this model can deliver the fastest start on site, though not always the fastest completion.
Changes. Easiest of the three to accommodate, because packages not yet tendered can absorb changes at market price.
What you need in-house. The most: a technical team able to take decisions on design, cost and programme continuously.
Construction management suits experienced employers with their own project department, phased developments, and refurbishment where scope is discovered as work proceeds.
Ask four questions in order.
1. How firm is the design at signature? Firm favours turnkey; evolving favours design-build; discovered-as-you-go favours construction management.
2. How much price certainty do you need, and when? If financing or a board approval depends on a fixed figure before work starts, turnkey or a guaranteed maximum price is the practical answer.
3. What technical capacity will you keep? Be honest. A model that assumes daily employer decisions will fail if your team is part-time or in another country.
4. How likely are changes? Frequent change plus a lump sum contract is the most expensive combination in construction.
When the project is in a different country from the employer, distance itself becomes a risk. Site visits are infrequent, time zones slow decisions, and imported materials sit outside your visibility for weeks at a time. That pushes most foreign employers towards turnkey or design-build with a single accountable contractor — and makes the contractor's local presence, procurement plan and reporting discipline more important than the model on the cover page.
Whatever the model, three provisions deserve attention at signature: a written change control procedure with a price mechanism, a payment schedule tied to verifiable milestones rather than dates, and a handover definition listing exactly which documents, warranties, spares and training are included.
The contract sum usually looks higher because it contains the contractor's risk margin. Whether the project costs more depends on what happens afterwards: turnkey often finishes closer to its original figure, while models with open cost tend to start lower and move.
The terms overlap. EPC — engineering, procurement, construction — is the term more common in industrial and energy projects, where process equipment and performance guarantees dominate. Turnkey is the term more common in buildings. Both describe single-point responsibility for a completed, functioning facility.
Rarely without renegotiating the whole contract. It is far cheaper to spend two weeks choosing the right model than to convert one into another after work has started.
None inherently. Quality comes from the specification, the supervision and the closing of the snagging list. What the model determines is who is answerable when quality falls short — and single-point models make that answer shorter.