Design and build or traditional procurement: which suits my project?
Choose the procurement route around design responsibility, the information available and the decisions you want to retain.
by Jack Butler-Kettle · About 3 min readShare
The answer
Traditional procurement usually separates the client’s design appointments from the building contract. Design and build places agreed design and construction responsibilities with the contractor.
Neither route guarantees a complete design, fixed final cost or freedom from changes. The brief, documents, appointments and amendments determine the actual allocation.
Key differences
Scroll across to read all columns.
| Question | Traditional | Design and build |
|---|---|---|
| Who designs? | Client-appointed designers typically develop the design. | The contractor undertakes the agreed design responsibility. |
| What is tendered? | Typically drawings and specifications describing the required work. | Typically employer requirements and the proposed design/commercial response. |
| Who controls design detail? | The client’s design team normally retains a direct role. | Control depends on the requirements, approvals and contractor’s design obligations. |
| When is price dependable? | When the priced scope and adjustment rules are sufficiently clear. | When requirements, proposals and retained risks are sufficiently clear. |
| How are changes managed? | Under the selected contract and appointment procedures. | Under the selected contract, with attention to changes in requirements. |
Compare responsibilities and decisions
The table describes common arrangements, not rules overriding a signed contract.
Match the route to design maturity
Identify what is already designed and what remains open. A tender issued with unresolved design can produce qualifications or risk allowances under either route.
Ask who resolves conflicts and who carries responsibility for designs developed before and after appointment. Novation or retained client design needs specific consideration.
The JCT contract guidance helps identify the relevant family; the form and edition still require project-specific selection.
Compare price certainty with flexibility
Examine what is fixed and what can change: scope, quantities, allowances, inflation and client instructions. Design and build is not a guarantee against every adjustment.
Late changes can affect both price and programme. Price the client’s required flexibility instead of assuming it is free.
See fixed-price versus cost-plus for a separate comparison of charging arrangements.
Confirm the team and approval arrangements
Determine who gives instructions, checks design compliance and administers the contract. A QS cost appointment does not automatically provide all these functions.
Read the contract administrator and employer’s agent comparison. State authority and limitations in the appointments.
Direct appointment of individual trades also creates coordination and interface decisions. Assess these explicitly rather than treating that route as a smaller main contract.
Choose and document the procurement strategy
Compare options against the brief, design readiness, programme, market interest and client resources. Record the risks retained under each option.
Our Contractor tendering and comparison or Development package procurement can compare the commercial implications.
The RICS employer’s agent guidance explains the importance of defining that role where it is appointed.
Example
The facts
A fictional client has outline accommodation needs but unresolved performance and finish requirements.
What happens
Calling the tender design and build does not remove those missing decisions.
The team defines the employer’s requirements and identifies retained design and approval responsibilities.
They compare procurement options using the clarified scope, available time and client capacity.
What this shows
The route follows the project’s needs. A label alone does not transfer every risk.