Design and Build vs Separate Architect — Which Procurement Route is Right for You?

**The traditional route**: In the traditional procurement route, the homeowner engages an architect or designer separately (usually on an hourly rate or a percentage of the project value — typically 8–15% for a residential extension or loft conversion). The architect: 1. Develops the design concept with the homeowner 2. Prepares planning drawings and submits the planning application 3. Develops the technical design (Building Regulations drawings) 4. Coordinates with a structural engineer and other consultants 5. Prepares a specification document 6. Helps the homeowner issue the documents to a list of builders for competitive tender 7. (Optionally) acts as contract administrator and inspects works on site

• **Advantages of the separate architect route**:
• •**Independent design**: the architect's interest is in the quality of the design, not in minimising build cost for a contractor's margin. You get design that is undiluted by commercial pressure.
• •**Competitive tender**: issuing to multiple builders creates price competition — you can compare apples with apples against the same specification.
• •**Expertise**: a good architect brings spatial thinking, material knowledge, and experience of what Planning and Building Control will require that most homeowners cannot replicate.
• •**Contractor oversight**: the architect can act as a client's representative during construction, reviewing work and certifying payments.

• **Limitations of the separate architect route**:
• •**Cost and time**: architectural fees add cost (8–15% of project value) and the design process takes time (3–6 months for planning, technical design, and tender).
• •**Coordination gap**: once the builder takes over from the architect's drawings, the integration between design intent and build execution is not always seamless. Builders may 'value engineer' details or interpret drawings differently.
• •**Design that is not buildable**: some architects design projects that are technically challenging or expensive to build without fully appreciating the construction cost implications.
• •**Multiple appointments**: the homeowner is managing two relationships (architect and builder) rather than one.

**What design and build means**: In a design-and-build procurement, a single entity — the design-and-build contractor — provides both the design and the construction. The homeowner deals with one party throughout.

• In residential construction, design-and-build typically works as follows:
• •The contractor's in-house team or associated architect prepares the planning and technical drawings
• •The structural engineer is novated to (or directly engaged by) the contractor
• •The contractor manages the full project from pre-construction through to handover
• •The homeowner has a single point of responsibility — one contract, one party to deal with

• **Advantages of design-and-build**:
• •**Single point of responsibility**: one contract, one party. If something goes wrong, there is no argument between architect and builder about whose fault it is — the contractor owns both.
• •**Buildability**: design decisions are made by people who also build — the design is inherently buildable because the contractor knows their own costs and methods.
• •**Speed**: eliminating the formal tender process (which takes 4–8 weeks after design is complete) and the design-and-build procurement can be faster overall.
• •**Cost certainty**: the contractor prices the project against their own design — they own the design risk. If a design detail turns out to be more expensive to build than anticipated, that is the contractor's problem, not the homeowner's.
• •**Integration**: the relationship between design intent and build execution is tighter — there is no gap between what the architect drew and what the builder is prepared to build.

• **Limitations of design-and-build**:
• •**Design independence**: the contractor has a financial interest in designs that minimise cost and maximise margin. The homeowner may receive design that is functional but not ambitious.
• •**Less design scrutiny**: without an independent architect reviewing the contractor's design, the homeowner may not get the same level of spatial or aesthetic thinking.
• •**Price comparison**: it is more difficult to compare design-and-build offers from different contractors because each has prepared their own design — unlike the traditional route where all contractors are pricing against the same specification.
• •**Less appropriate for complex or bespoke design**: where the project is architecturally ambitious, a standalone architect who is expert in that type of design will typically produce a better result.

• **Use a separate architect when**:
• •The project is architecturally complex or bespoke (a contemporary extension with unusual geometry, a listed building, a project in a Conservation Area where design quality will be scrutinised)
• •You have a strong aesthetic vision and want an expert to help you realise it
• •You want to competitively tender to multiple builders
• •You want independent oversight of the contractor during the build
• •The budget is large enough to absorb 8–15% architectural fees without compromising the build quality

• **Use design and build when**:
• •The project is relatively standard (a rear extension, a loft conversion, an HMO conversion) where the design follows well-understood rules
• •Speed and simplicity are important — you prefer one contract and one point of contact
• •You want the contractor to own design risk as well as construction risk
• •You have a clear brief but do not have a detailed design vision that needs to be independently protected
• •You have had a good experience with or strong recommendation for a specific design-and-build contractor

**A hybrid approach**: Many homeowners use a partial hybrid: they engage an architect for the planning stage only (design concept + planning application), then hand the project to a design-and-build contractor for technical design and construction. This gives the benefit of independent design at the planning stage — when design quality is most scrutinised — while simplifying the construction phase. RCB Design & Build routinely works alongside homeowners' architects in this way.