# Design-Build Delivery Design-build (D&B) is a procurement method in which a single entity — the design-build contractor — assumes responsibility for both the design and construction of the building under a single contract with the client. It is the dominant procurement route globally and accounts for approximately 40-50% of UK construction projects by value. For the practicing architect, D&B fundamentally alters the professional relationship: in traditional procurement the architect serves the client directly; in D&B the architect may be novated to the contractor, engaged directly by the contractor, or retained by the client as an independent monitor. Understanding the implications for design control, liability, and professional independence is critical. --- ## Table of Contents - [How Design-Build Works](#how-design-build-works) - [Variants of Design-Build](#variants-of-design-build) - [The Novation Process](#the-novation-process) - [Employer's Requirements](#employers-requirements) - [Contractor's Proposals](#contractors-proposals) - [Architect's Role in D&B](#architects-role-in-db) - [Advantages and Disadvantages](#advantages-and-disadvantages) - [Contract Forms](#contract-forms) - [Risk Allocation](#risk-allocation) - [Design Quality in D&B](#design-quality-in-db) - [See Also](#see-also) --- ## How Design-Build Works ``` Client ──────── Single Contract ──────── D&B Contractor │ ┌─────────┼─────────┐ │ │ │ Architect Engineers Subcontractors (novated (novated (domestic) or direct) or direct) ``` 1. **Client** develops the brief and appoints an architect to prepare concept design and Employer's Requirements (ER) 2. **Employer's Requirements** define what the client wants — performance standards, design quality, spatial requirements 3. **D&B contractors** tender with **Contractor's Proposals** (CP) — responding to the ER with a design, programme, and price 4. **Client** selects contractor based on quality, price, and programme 5. **Contractor** assumes responsibility for completing the design and constructing the building 6. **Architect** is either novated to the contractor or retained by the client as an independent monitor (Employer's Agent) --- ## Variants of Design-Build | Variant | Design Stage at Tender | Design Responsibility | Client Design Control | |---------|----------------------|----------------------|---------------------| | **Pure D&B** | Performance specification only | Contractor (full) | Minimal (output-based) | | **Develop and Construct** | Stage 2-3 concept/coordinated design | Contractor completes (Stage 4+) | Moderate (design is fixed at tender) | | **Novated D&B** | Stage 2-3 by client's architect; architect novated to contractor | Contractor (with novated team) | Moderate-high (continuity of designer) | | **Design-Build-Operate (DBO)** | Performance specification | Contractor (design, build, and operate) | Minimal during design; contractual during operation | | **Design-Build-Finance-Operate (DBFO/PFI)** | Performance specification | SPV (special purpose vehicle) | Output specification; 25-30 year contract | | **Two-stage D&B** | Stage 2-3; contractor joins as pre-construction partner | Collaborative (contractor + architect) | High (collaborative development) | **Two-stage D&B** is increasingly popular because it combines early contractor involvement (buildability, cost certainty, programme input) with retained design quality during the development stages. --- ## The Novation Process Novation transfers the architect's contractual relationship from the client to the contractor: **Before novation**: Architect → Client (professional service agreement) **After novation**: Architect → Contractor (novated agreement; same terms) ### Key Issues with Novation | Issue | Implication | |-------|-----------| | **Dual loyalty** | The architect designed for the client but now works for the contractor — conflicting interests | | **Design control** | The contractor may seek to reduce specification to improve margin — architect must maintain quality | | **Liability** | The architect owes duty of care to the contractor (contractual) and potentially to the client (collateral warranty or tortious) | | **Fitness for purpose** | D&B contracts may impose a fitness-for-purpose obligation on the contractor — this can flow through to the novated architect. Architects provide reasonable skill and care, not fitness for purpose. This must be clarified in the novation agreement | | **Cost cutting** | Post-novation value engineering may compromise design intent — the architect should resist changes that affect performance or quality | | **Professional independence** | The ARB/RIBA Code of Conduct requires the architect to maintain professional independence regardless of employment arrangement | **Best practice**: The novation agreement should explicitly state that the architect's obligation remains one of reasonable skill and care (not fitness for purpose), and that the architect retains the right to refuse instructions that would breach professional standards or Building Regulations. --- ## Employer's Requirements The ER document defines the client's requirements and is the benchmark against which the contractor's design is measured: | Content | Detail | |---------|--------| | **Design intent** | Concept drawings (Stage 2/3); spatial requirements; design quality standards | | **Performance specification** | U-values; air tightness; acoustic standards; fire strategy; environmental targets | | **Room data sheets** | Specific requirements for each room/space type | | **Material standards** | Minimum quality; approved manufacturers; prohibited materials | | **Planning requirements** | Planning conditions; Section 106 obligations; design code | | **BIM requirements** | EIR; LOD at each stage; CDE; IFC requirements | | **Programme requirements** | Key milestones; phasing; sectional completion | | **Contract requirements** | Form of contract; warranties; bonds; insurance | **The quality of the ER determines the quality of the building**: A vague ER produces a lowest-common-denominator response. A detailed, well-specified ER with clear design quality benchmarks produces a building that meets the client's expectations. --- ## Contractor's Proposals The CP is the contractor's response to the ER — it defines what the contractor will design and build for the tendered price: | Content | Purpose | |---------|---------| | **Design proposals** | Drawings and specification responding to ER design intent | | **Design deviations** | Any departures from the ER (must be clearly identified) | | **Programme** | Construction programme; key milestones | | **Pricing document** | Lump sum; or activity schedule; or cost breakdown | | **Method statement** | Construction methodology; temporary works | | **Design team** | Named architects, engineers, specialists | | **Health and safety** | Pre-construction information response | **Contract hierarchy**: The ER and CP together form the contract. Where they conflict, the ER typically prevails (this must be stated in the contract). Any CP deviations not accepted by the client before contract award should be rejected. --- ## Architect's Role in D&B | Role | Appointed By | Scope | |------|-------------|-------| | **Pre-contract architect** | Client | Prepare ER; concept design; planning application; tender evaluation | | **Novated architect** | Contractor (after novation) | Complete technical design; site inspections; certification | | **Employer's agent** | Client (retained) | Monitor contractor's design; protect client's interests; administer contract | | **Independent design reviewer** | Client | Review contractor's design submissions for compliance with ER | | **Monitoring architect** | Client | Periodic design review and site inspection; limited scope | **Fee implications**: In D&B, the architect's fee for pre-contract work (ER preparation) is typically 25-40% of a full-service fee. If novated, the contractor pays the remaining fee for technical design and site work. If retained as Employer's Agent, the fee for monitoring is typically 10-15% of full-service fee. See [[Architectural Fee Structures]]. --- ## Advantages and Disadvantages ### Advantages | Advantage | Explanation | |-----------|------------| | **Single point of responsibility** | Client deals with one entity for design and construction | | **Cost certainty** | Lump sum price agreed before construction | | **Programme** | Overlapping design and construction can reduce overall programme | | **Buildability** | Contractor's input into design improves constructability | | **Risk transfer** | Design risk transfers to contractor | ### Disadvantages | Disadvantage | Explanation | |-------------|------------| | **Design quality risk** | Contractor may prioritise cost reduction over design quality | | **Client loses design control** | Post-contract design changes require variations (cost implications) | | **Specification reduction** | Contractor may substitute cheaper materials/systems within ER tolerances | | **Architect's independence compromised** | Novated architect may face pressure to approve substandard work | | **Tender comparison difficult** | Different CP designs are hard to compare like-for-like | | **Variations are expensive** | Changes after contract award attract premium pricing | | **Quality depends on ER quality** | Weak ER = weak building | --- ## Contract Forms | Contract | Jurisdiction | Key Feature | |----------|-------------|-------------| | **JCT Design and Build 2024** | UK | Standard D&B; lump sum; architect as Employer's Agent | | **NEC4 Engineering and Construction Contract (Option A)** | UK/International | Activity schedule; early warning; collaborative | | **FIDIC Yellow Book** | International | Plant and Design-Build; engineer administers | | **AIA A141** | US | Standard D&B agreement | | **DBIA** | US | Design-Build Institute of America standard form | | **GC/Works** | UK Government | Government D&B contract | --- ## Risk Allocation | Risk | Traditional | Design-Build | |------|-----------|-------------| | **Design adequacy** | Architect (reasonable skill and care) | Contractor (may include fitness for purpose) | | **Design coordination** | Architect (lead consultant) | Contractor | | **Ground conditions** | Usually client (unless contractor inspects) | Depends on ER/CP; often shared | | **Planning** | Client (with architect support) | Client (pre-contract); contractor may accept risk post-contract | | **Building Regulations** | Architect | Contractor | | **Programme** | Contractor (construction); architect (design) | Contractor (both) | | **Cost** | Shared (provisional sums; variations) | Contractor (lump sum) | | **Quality** | Architect/clerk of works | Contractor (per ER standards) | --- ## Design Quality in D&B Maintaining design quality in D&B is the architect's primary professional challenge: 1. **Front-load the design**: Develop the design to the highest feasible level before tender (Stage 3 minimum) — this limits the contractor's scope to degrade quality 2. **Specify outcomes, not inputs**: Performance specifications are harder to undercut than prescriptive specifications 3. **Benchmarking**: Include design quality benchmarks in the ER — reference buildings, material standards, detail quality levels 4. **Design review mechanism**: Retain the right to review and approve the contractor's design submissions 5. **Sample panels / mock-ups**: Require full-scale mock-ups of critical facade and interior elements for approval before bulk installation 6. **Resist value engineering**: Challenge every proposed substitution against the ER design intent — not just cost and programme 7. **Document everything**: Record all design decisions, approvals, and deviations --- ## See Also - [[Traditional Design Bid Build]] - [[RIBA Plan of Work]] - [[Architectural Fee Structures]] - [[Construction Specifications Writing]] - [[BIM Fundamentals and LOD]] - [[Construction Project Management]] --- #practice #designbuild #procurement #contracts #delivery #novation