Do you need an architect or an architectural designer?

What does each title legally mean?

This is the point almost every comparison article gets wrong. The Architects Act protects the title. It does not reserve the act of designing a building, preparing planning drawings, or submitting a building regulations application. Anyone may do that work; not everyone may call themselves an architect while doing it.

So the useful question is not "which title?" but "what does this person actually produce, and who carries the professional indemnity insurance if it is wrong?"

When is an architect the right call?

An architect's training is broad and design-led, and on the right project that breadth earns its fee several times over: a constrained infill plot, a change of use, a listed building, a scheme where the arrangement of space is the whole point, or a contract where you want a professional running the builder.

It is honest to say so. A rear extension that repeats what forty houses on the street have already built is not that project.

When is a technologist or designer enough?

Architectural technology is the technical half of the discipline — construction detailing, Building Regulations compliance, the coordination between the drawing set and what actually gets built. On a standard extension, loft or garage conversion, that is where the risk sits.

• The measured survey is right, so the design fits the building that exists rather than the one on the deeds.
• The planning drawings answer the borough's own guidance before the officer has to ask.
• The building regulations package resolves structure, thermal performance, ventilation and drainage as one coordinated set.
• The builder prices from drawings, not from a conversation.

How do the fee models differ?

A percentage fee scales with the build: the more your project costs, the more the design costs, whether or not the drawing work grew. A defined-deliverable fee prices the package — survey, drawings, submission, technical set — and is easier to compare between practices.

Neither is inherently better. Percentage fees suit projects where scope genuinely evolves; fixed scope suits projects where it does not. What matters is knowing which you have signed.

What should you ask either of them?

• Who carries professional indemnity insurance on this work, and to what level?
• Will you produce a measured survey, or design from my sketches?
• Does the package include the building regulations set, or planning only?
• Who submits the application and answers the case officer's questions?
• Have you submitted in this borough before, and what did they push back on?

The last question is the most revealing. Boroughs differ sharply in what they will accept — on mansard profiles, on rooflights to the front, on the depth of a side return — and someone who works there regularly will answer it immediately.