Architect or architectural designer: which do you need?

Searches for an architectural designer for a house extension usually come from someone who has seen two quotes of very different sizes, or who has been told a designer can draw the same plans for less. That can be true in some cases and unhelpful in others. This guide sets out what the labels legally mean, what the other professional routes offer and the kinds of project where paying for an ARB-registered architect is most likely to be worthwhile.

What does the title architect protect?

The Architects Act 1997 bars anyone from practising or carrying on business under a name, style or title that contains the word architect unless they are on the register kept by the Architects Registration Board (section 20). Naval architect, landscape architect and golf-course architect are carved out. Breaking the rule is an offence, with a fine on summary conviction of up to level 4 on the standard scale (section 21).

What the Act leaves open matters just as much. ARB's guidance for the public says anyone, architect or not, can lawfully provide architectural services in the UK, and that the protection does not reach terms such as architectural consultant or architectural assistant (ARB, who can use the title). Nothing in that guidance makes designer a protected word either, so check ARB directly if you meet a description you are unsure about. In plain terms, the title tells you the person has met the register's requirements and is answerable to a regulator. It does not stop someone else from drawing your plans.

What can an architectural designer or technologist do?

Architectural designer is a description rather than a credential, which means it covers a wide range: from highly capable people with years of residential experience to someone who has only recently started. That is why the useful question is not which label they use but what they can show. One route with a recognised qualifying process is the Chartered Architectural Technologist, a title awarded by the Chartered Institute of Architectural Technologists (CIAT). CIAT states that it is a legally protected title and descriptor limited to people who have completed its qualifying process (CIAT, recommended titles and descriptors). The government's regulated professions record describes the profession as regulated under Royal Charter and notes that no activities are reserved to it, since restrictions apply to the use of the title only (UK Regulated Professions Database).

The same record says chartered architectural technologists are qualified to design, manage and lead projects of all types from inception to completion, with no restriction on size, type, function or use. In everyday terms, that makes a chartered technologist a credible option for detailed technical design, building regulations drawings and project management on a typical home extension.

When is an ARB-registered architect worth it?

Choose registration and the regulator's backstop when the stakes or the complexity are higher. Three situations stand out.

• Heritage assets. Listed building consent is needed for work that is likely to affect a listed building's special character, and it is a criminal offence to do such work without it (Planning Portal). A mistake can be prosecuted, with penalties on conviction of up to six months' or two years' imprisonment, a fine or both, depending on the court (Planning (Listed Buildings and Conservation Areas) Act 1990, section 9). Work like this rewards an architect who has handled heritage statements before. See listed building projects.
• Difficult sites and layouts. Where a plot is constrained, levels change, neighbours overlook or the existing structure limits what can be done, the value is in design judgement more than drawing.
• Design-led projects. If the point of the project is how the space feels, the light it gets or how it connects to a garden, a design-trained architect's contribution is largely the decision-making you are paying for.

When might a designer or technologist be enough?

A project with a clear brief, a conventional layout and no designations can be well within the range of a competent designer or chartered technologist. A single-storey rear extension on an unlisted house, a loft with a standard roof form or an internal reconfiguration are examples where the main task is clear drawings, coordination with structural input and good communication. The guide to extensions and the loft conversion page explain the rules those projects meet.

Here a lower fee is not automatically a lower-quality service, but you carry more of the checking yourself. Confirm that the person has relevant professional indemnity insurance, because ARB's own checklist for clients recommends terms of engagement that confirm adequate and appropriate insurance cover, an explanation of what to do if you have a complaint and how disputes are settled (ARB, checklist before hiring). That list is aimed at architects' clients, but every one of those items is just as reasonable to ask of anyone else.

How do I check who I am dealing with?

If a person or firm uses the word architect, find them on the Architects Register by registration number, name or business address and compare it with what they told you. ARB opened 892 new title cases in 2025, up from 586 in 2024, so misuse does happen (ARB, 2025 year in review). If they describe themselves as a chartered technologist, ask for their CIAT membership details and verify them with the institute. If they use neither, ask what they are qualified in and for examples of similar completed work. The sister guide on how the two architect bodies differ covers the institute side.

What should I ask before choosing?

1. Which qualification or registration do you hold, and where can I verify it?
2. Can you show two or three completed projects like mine, and may I speak to those clients?
3. Who will do the drawings and who will deal with the council?
4. What insurance do you hold, and what does it cover?
5. What is included in the fee, and what is not? See how architect fees are structured.
6. What will you do if the council asks for changes, and is that inside the fee?
7. What is your complaints process and what are the cancellation terms?

Compare at least two written proposals against the same brief. Differences in the scope sections usually explain differences in price better than the totals do.