Architect vs. Design-and-Build Cost Comparison

Usually cheaper in total, not always on the face of it. An architect's fee on a standard rear extension is around 11% of construction cost. Our D&B fee is around 7%. On a £70,000 extension that's a £2,800 saving on the design fee alone. But the bigger gap comes from the contractor side. When a project is separately tendered, the contractor prices design risk into their markup because they didn't draw the plans and they don't fully own the details. That adds 15% on top of the architect's 11%. With D&B the design and build are integrated, so we carry the risk on both and price accordingly. The total is usually 8-15% less than the architect-plus-tender route. Faster too, because there's no tender period.

Three situations where an architect earns their fee. Listed buildings or conservation area work where design scrutiny is high and the planning history matters — an architect with conservation area experience navigates that better than a D&B contractor focused on delivery. Complex or bespoke projects where you want a specific design vision and you're willing to spend time developing it with a specialist. And situations where you're not happy handing control to a single contractor — some clients prefer the checks-and-balances of separate designer and builder. The downside of that separation is coordination: the architect draws something, the contractor queries it, revisions go back and forth, timelines extend. For standard residential extensions and renovations I think D&B usually serves people better.

We start with a free site visit and a brief from you. From that we produce concept drawings, which we refine through one or two meetings until you're happy. Those drawings go for structural calculations and Building Regulations submission. Once approval comes through, we build to the approved drawings — same team, same fixed price. The key difference from the traditional route is that there's one contract covering design through to completion. If there's a discrepancy between the drawings and the build, that's our problem to resolve, not yours. We've done it this way for ten years. The feedback we get consistently is that clients find the single-point-of-contact model less stressful than managing a separate architect and contractor relationship.