Do I need an architect for an extension?
Not legally, but you need someone competent to produce drawings and a structural engineer for the calculations. For a straightforward side return, a design-and-build contractor or architectural technologist is usually sufficient; for anything architecturally ambitious or in a conservation area, an architect earns their fee.
There is no legal requirement to use an architect. What you do need is a set of drawings good enough for a planning application and building control, and structural calculations from a qualified engineer. Those can come from an architect, an architectural technologist, or a design-and-build contractor with in-house design capability.
For a standard Fulham side return — a well-understood project on a well-understood house type — a design-and-build route is usually the efficient choice. One contract covers design, planning and construction, and there is no gap for anyone to point at if something goes wrong. It also tends to be faster, since the person designing it knows exactly what it will cost to build.
Where an architect is worth paying for separately: a difficult site, a listed building or conservation area where the design case has to be argued to a conservation officer, or a project where the architecture genuinely matters to you. An architect works for you alone and will push the design further than a contractor optimising for buildability. We will say honestly which route suits a given project — sometimes the answer is that you should hire an architect and not us for the design.
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