Local Architects Explained: What They Do, What They Charge and How to Pick the Right One

Fees for the same extension can range from 3 per cent of build cost to 15 per cent, and the gap is not explained by talent. It is explained by scope, and almost nobody compares scope properly. That spread is the single most useful thing to understand before contacting local architects about a project.

RIBA abolished its published fee scale in 2009. Since then every practice prices case by case, which is why two proposals for one house can look nothing alike.

What an Architect Actually Delivers

The work splits into distinct stages, and you probably do not need all of them.

The RIBA Plan of Work runs from stage 0 to stage 7. Most homeowners need stages 1 to 4, covering brief, concept design, developed design and technical design. Stage 5 is construction monitoring, and it is optional rather than automatic.

In practical terms, a full domestic service covers the measured survey of the existing building, feasibility and concept design, the planning application drawings and supporting statements, the building regulations drawing package, tendering to builders, and contract administration during the build.

A planning only service covers considerably less. Drawings sufficient to obtain permission, and nothing beyond it.

Both are legitimate offers. They are not comparable prices.

The Three Fee Models

Percentage of build cost is the most common approach on domestic work. Across the UK, full service fees generally sit between 7 and 15 per cent, and London practices typically quote 8 to 15 per cent with the average nearer 10 to 12.

The percentage falls as project value rises, because the fixed cost of running a project does not scale proportionally. Published guidance puts it around 12 to 15 per cent on projects under £50,000, 9 to 12 per cent between £100,000 and £250,000, and 7 to 10 per cent above £500,000.

Fixed fee offers cost certainty and suits well defined scopes. Figures range from roughly £1,200 for straightforward planning drawings up to £25,000 or more for a full new build service. For a single storey rear extension, expect somewhere around £1,200 to £2,400 for planning drawings alone, or £2,200 to £4,500 for planning plus a building regulations package.

The disadvantage is that any change to the brief after the fee is fixed gets billed as an extra at hourly rates.

Hourly rates suit feasibility work, consultations and advisory tasks. UK rates generally run £70 to £160 an hour, with London typically 20 to 30 per cent above national figures. Rates vary by seniority, so a technician sits at the bottom of the range and a director with two decades of local planning experience at the top.

One caution worth taking seriously. Hourly engagements expand. Agree a written cap before commissioning hourly work, or switch to a fixed fee once the scope is clear.

VAT is charged in addition to all of these.

The Questions Worth Asking

1. Which RIBA stages does this cover?

A good answer names the stages and lists deliverables. If a proposal does not say, you cannot compare it to anything. Ask for the schedule of services, which should also state exclusions.

2. Is the fee percentage, fixed or hourly, and what triggers extras?

A good answer explains the model and where the boundaries sit. Percentage fees are sometimes only revised where the cost estimate moves by more than 10 per cent, which allows for reasonable variation before fees adjust. Ask what happens if you change your mind at technical design stage.

3. What is your ARB registration number?

A good answer supplies it without hesitation. Only ARB registered professionals may use the title architect in the UK. Reluctance here is a genuine warning sign.

4. What professional indemnity insurance do you hold?

A good answer gives a figure and offers the policy summary. All ARB registered architects must hold professional indemnity insurance, and cover typically ranges from around £250,000 for very small practices to several million for larger ones. Your project value should sit comfortably within it.

5. Which contract will we use?

A good answer names a standard form. The RIBA Standard Contract and the RIBA Domestic Standard Project Agreement both exist for this purpose. A practice that will not use a recognised form is asking you to accept unnecessary risk.

6. Do structural calculations sit inside or outside this fee?

A good answer is unambiguous either way. Building Control needs a structural calculation pack covering beams, foundations and connections before signing off structural work. Whether that comes from the practice or from a separate consultant changes both the cost and the coordination.

7. What is your experience with this council?

A good answer references specific policy or recent decisions. This matters more than most people expect, and the next section explains why.

8. Can I speak to two recent clients?

A good answer offers contacts rather than testimonials. An extension project runs months, sometimes longer. Communication quality is a functional requirement, not a preference.

Why Council Knowledge Is Worth Paying For

Planning outcomes vary between boroughs for reasons that are documented rather than mysterious, and knowing the local position changes what gets designed.

Conservation area coverage differs enormously. Some London boroughs have a handful of designations, others have dozens. Inside one, side extensions cease to be permitted development and materials become part of the planning case rather than a tender decision.

Article 4 directions are a separate control that often overlaps with conservation areas. A property can sit outside every conservation area in a borough and still have permitted development rights removed by a direction, sometimes drawn around specific house numbers.

Planning history matters too. Previous permissions on a property sometimes carry conditions removing permitted development rights, and previous extensions count against the 50 per cent curtilage allowance, measured against the original dwelling as it stood on 1 July 1948 or as first built if later.

None of that is discoverable from a national guide. It is address level research.

What This Looks Like in Practice

West London illustrates the point well. Ealing has a large and varied housing stock, from Victorian and Edwardian terraces through substantial interwar suburban semis and detached houses, and the planning position shifts across it.

On a plot with intact permitted development rights and a generous garden, a scheme can proceed without an application at all, which changes both the timeline and the fee basis. On a plot inside a conservation area, the same brief becomes a full application with a heritage statement addressing the specific character appraisal for that area.

Those are two different projects with two different scopes, and quoting them identically would be misleading. Which is why architects ealing homeowners should be confirming designation status and any Article 4 direction on the exact address before producing a fee proposal, not after.

Extension Architecture’s approach is to establish the consent route first, because scope follows the planning position rather than the brief.

How to Compare Proposals Sensibly

Get two or three written fee proposals and compare them on a like for like basis. Same stages, same deliverables, VAT status confirmed on all of them.

Never engage on a verbal estimate.

And weigh more than the number. A practice with relevant experience in your borough, a portfolio of comparable work and clients willing to speak to you is usually better value than the cheapest proposal with the vaguest scope.