Design and Build vs Traditional Procurement: Which Suits Your Project?
Short answer: in traditional procurement you appoint designers to complete the design, then tender it to contractors who build what's drawn, so you keep control of the design but carry the risk of gaps between design and construction. In design and build, one contractor is responsible for designing and building, usually for an agreed price, so you get a single point of responsibility and earlier cost certainty, in exchange for handing over control of the detailed design.
Neither is better in every case. The right answer depends on how much of the design you want to control, how fixed your budget and date are, and how much management time you have.
This guide compares the two routes from the point of view of a business owner or occupier commissioning a fit-out, refurbishment or conversion. Craftex works mainly as a design and build contractor, so we've tried to be straight about when traditional is the better choice.
How each route works
Traditional (design, bid, build)
- You appoint an architect or interior designer, engineers and usually a cost consultant.
- They develop the design in detail and prepare tender documents.
- Contractors price the complete design.
- You appoint a contractor on a building contract (for example a JCT Standard Building Contract, Intermediate or Minor Works contract, depending on size).
- Your designers stay with you through construction, administering the contract and answering the contractor's questions.
Design and build
- You set out what you need: an employer's requirements document, which may be a short brief or a developed concept.
- A contractor responds with its proposals and price.
- You appoint one contractor to design and build, usually on a JCT Design and Build Contract.
- The contractor develops the detailed design with its own designers (or with yours, transferred to it by novation) and builds it.
Variations you'll hear about: two-stage design and build (the contractor joins early on a pre-construction agreement, then prices the developed design), and traditional with a contractor's designed portion (traditional overall, with specific packages such as mechanical services designed by the contractor).
Side by side
| Traditional | Design and build | |
|---|---|---|
| Who designs | Your designers, working for you | The contractor, using its own or novated designers |
| Responsibility for design gaps | Mostly yours, between designer and contractor | The contractor's, within its design obligation |
| Cost certainty | Good when the design is complete at tender; changes and design gaps add cost later | Earlier, against the employer's requirements; your changes still cost money |
| Speed | Slower: design must be finished before tender | Faster: design and construction overlap |
| Control of design and quality | High: you instruct your designers | Lower: you control through the requirements, reviews and approvals |
| Points of contact | Several (designers, cost consultant, contractor) | One |
| Client management effort | Higher | Lower |
| Suits | Design-led or heritage projects, complex briefs that will change, clients with strong in-house project teams | Fixed budgets and dates, occupiers who want one accountable team, repeatable or well-defined scopes |
Where traditional procurement wins
- You want the design exactly as your designer intends. Flagship interiors, listed buildings and brand-defining spaces often justify the control.
- You'll make lots of decisions as you go. If the brief is still forming, a contractor pricing a moving target is a recipe for variations.
- You have a capable client team. If someone on your side can manage designers, cost and contract, you can get the benefit of competitive tendering on a complete design.
- Like-for-like comparisons. Tendering one complete design lets you compare contractors' prices for the same thing.
Where design and build wins
- The date matters. Overlapping design and construction saves time, and one party owns the programme.
- The budget is fixed. The contractor prices against your requirements early, and designs to them.
- You don't want to manage the interfaces. On a traditional job, the gap between what was drawn and what can be built sits with you. Design and build puts that gap inside one organisation.
- Buildability shapes the design. The people pricing and building the job are in the room while it's designed, so cost and programme feed the design rather than react to it.
That last point is the one we see most clearly in our own work. When the client of Medusa Spa & Beauty in Knightsbridge came to us, the design was at RIBA Stage 2, concept only, with cost estimates already discussed at earlier stages. Because our design and construction teams work together, we could see the full cost impact of the concept and propose more affordable solutions, ending with a design that delivered the client's vision within her budget: 180 sq m over four floors, designed and built in 17 weeks.
At Portsoken House in Aldgate, our in-house team designed the conversion of an abandoned warehouse into 1,550 sq m of offices over two floors. Keeping the design and the build under one roof gave the client accurate pricing and considerable savings.
The risks of design and build, and how to manage them
Design and build isn't a way to stop thinking about the design. The common problems, and the fixes:
- Vague employer's requirements. If you don't say it, you may not get it. Specify performance where it matters to you: finishes, acoustic separation, lighting levels, air conditioning standards, brand elements.
- Quality pressure. A contractor designing to a fixed price has an incentive to choose cheaper options. Review and approve key materials and samples, and build a sample or benchmark area for repetitive spaces.
- Losing your designer. If you've already appointed an architect or interior designer you trust, novation can move them to the contractor while keeping continuity. Agree it early.
- Changes cost more later. Freeze the brief before signing. Changes are possible but priced as variations.
- Who checks the work? On larger projects, keep an independent adviser (an employer's agent or project manager) to review the design and certify progress.
The risks of traditional procurement, and how to manage them
- Incomplete design at tender. Gaps become variations. Don't tender until the design is genuinely complete, or accept a provisional sum strategy with your eyes open.
- Slower start. Design, then tender, then build. Use early contractor involvement or enabling works to save time.
- Blurred responsibility. When something goes wrong, the designer and contractor may each point at the other. Clear drawings, a strong contract administrator and good records help.
- More of your time. Budget for client-side management.
Contracts: the JCT families
Most UK fit-outs use JCT contracts. The 2024 editions are current. In broad terms:
- Design and Build Contract (DB) for design and build;
- Standard Building Contract (SBC) for larger traditional projects, with options for quantities or a contractor's designed portion;
- Intermediate Building Contract (IC / ICD) for mid-sized traditional projects of straightforward complexity;
- Minor Works Building Contract (MW / MWD) for small, simple jobs.
Your adviser picks the form and the amendments. Whatever the route, CDM 2015 and the building regulations still need a principal designer and principal contractor appointed where more than one contractor is involved (see our guide to CDM 2015 client duties).
A simple way to choose
Ask three questions:
- How fixed is your design? Fixed and designer-led: lean traditional. Defined by need, not by drawing: lean design and build.
- How fixed are your budget and date? Very fixed: lean design and build.
- How much time do you have to manage the project? Little: lean design and build. A strong in-house or appointed team: traditional is workable.
If you're unsure, a two-stage approach often gives you the best of both: bring the contractor in early on a pre-construction agreement, develop the design together, then agree the price once the design is mature.
For more on who does what, see fit-out contractor vs general contractor, our tips on choosing a commercial contractor and our construction project management service.
