How Much Does an Architect Cost in London? A 2026 Guide to Fees, RIBA Stages & the Design-and-Build Alternative
"How much will an architect cost me?" is one of the first questions every London homeowner asks — and one of the hardest to get a straight answer to. This guide gives you the real 2026 numbers: how architects charge, what each RIBA stage actually costs, a worked example on a typical London extension, and the routes that can bring the total down — including when handing design and build to a single team makes more financial sense than appointing them separately.
The Three Ways Architects Charge
Almost every architect in London uses one of three fee structures — and understanding which one you're being offered is the difference between a predictable budget and an open-ended one.
- Percentage of construction cost — the most common model for full-service work. In London this runs 8–15%, with 10–12% typical for a standard residential project and 13–17% for complex, structurally demanding, or listed work. The trade-off: because the fee is tied to build cost, it rises if the build cost rises.
- Fixed fee — a single agreed sum for a defined scope (for example, "design through to Building Regulations drawings"). Best when the brief is clear; it gives you cost certainty up front. Typical London fixed fees run £5,000–£15,000 for an extension, more for a whole-house scheme.
- Hourly / time-charge — usually reserved for early feasibility work, ad-hoc advice, or open-ended briefs. Hardest to budget, so it's normally capped or used only for the initial stage.
Whichever structure you choose, fees are almost always invoiced in instalments that match the RIBA Plan of Work — so it pays to understand what those stages are.
The RIBA Stages — and What Each One Costs
The RIBA Plan of Work breaks a project into stages 0–7. As a homeowner you'll mostly deal with stages 1–4, with stage 5 (construction monitoring) as an optional extra. Here's how the architect's fee typically splits across them:
| RIBA Stage | What happens | Share of total fee |
|---|---|---|
| 1–2 — Brief & Concept | Site appraisal, your brief, initial design concepts and feasibility | ~20% |
| 3 — Planning | Developed design and the planning application | ~10–15% (≈30% cumulative to end of Stage 3) |
| 4 — Technical Design | Building Regulations drawings, technical detail, tender information | ~40% |
| 5–6 — Construction & Handover | Site inspections, contract administration, handover | ~30% |
Indicative fee distribution across RIBA stages for a typical London residential project, 2026. Most homeowners commission Stages 1–4, which accounts for roughly 70% of a full-service fee.
This is why you'll often hear that "getting to planning is about 30% of the fee." It also explains a common decision point: many homeowners take an architect to the end of Stage 4 (full Building Regs drawings and tender pack), then appoint a contractor to deliver — rather than paying the architect's Stage 5–6 fee for construction monitoring.
2026 London Fees: The Real Numbers
Bringing it together, here are indicative 2026 figures for London residential work:
| Scope | Typical fixed fee | As % of build cost |
|---|---|---|
| Rear extension — design to Building Regs (Stages 1–4) | £4,000 – £8,000 | ~8–12% |
| Extension/remodel — full service incl. site stage | £8,000 – £18,000 | ~10–15% |
| Whole-house refurbishment / large scheme | £15,000 – £40,000+ | ~10–15%+ |
| Listed building / conservation area | On application | ~13–17% |
Indicative London 2026 ranges. Fees exclude VAT, structural engineer, planning and Building Control fees. Sources listed at the foot of this guide.
A Worked Example
On a £120,000 single-storey rear extension and kitchen remodel, architect fees at the standard London percentage range work out at roughly £12,000–£18,000 for a full service. If you only take the architect to the end of Stage 4 (drawings and tender pack), expect to pay closer to £8,000–£13,000 — and you'll still need a structural engineer (typically £1,500–£4,000 on a project this size) on top.
Three Ways to Bring the Fee Down
- Only pay for the stages you need. If you have a contractor you trust to deliver, taking the architect to the end of Stage 4 and stopping there can save you the ~30% Stage 5–6 fee.
- Agree a fixed fee, not a percentage, once your brief is settled — so the fee can't drift upward with the build cost.
- Consider a design-and-build route, where one team carries both the design and the construction. This is where the structure of the project itself changes the maths — so it's worth understanding properly.
The Design-and-Build Alternative: When One Team Costs Less
In the traditional route, you appoint an architect, then separately tender the build to contractors. It gives you independent design oversight — and for many projects that's exactly right. But it has two cost characteristics homeowners often discover late: design and buildability are decided before a builder is involved, so value-engineering and cost reality arrive after the design is fixed; and you carry two sets of professional relationships and fees.
In a design-and-build route, a single team is responsible for the design and its delivery under one contract. The practical effect on cost is threefold: buildability and price are considered from the first sketch rather than bolted on at tender; there's a single point of accountability if something goes wrong on site; and you get an earlier, firmer figure because the people designing it are the people who will price and build it.
My Trusted Builder is a London design-and-build contractor. We provide architectural design in-house and deliver the build under a single JCT Design and Build Contract — one fixed price, one point of contact from planning through to handover, with structural works backed by a guarantee of up to 20 years. For homeowners weighing the two routes, our guide on design-and-build vs a traditional contract sets out exactly how each affects your price certainty.
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Book a free consultationFrequently Asked Questions
- How much does an architect cost for a house extension in London?
- For a single-storey rear extension in London in 2026, expect roughly £4,000–£8,000 for design to Building Regulations drawings (RIBA Stages 1–4), or £8,000–£18,000 for a full service including site monitoring. On a percentage basis that's about 8–15% of the construction cost. A structural engineer (typically £1,500–£4,000) is an additional, separate cost.
- Do I legally need an architect to get planning permission?
- No. There is no legal requirement to use an architect for a planning application or Building Regulations. You can use an architectural designer, an architectural technologist, or a design-and-build contractor who provides design in-house. What matters is that the drawings are accurate, compliant, and buildable. The title "architect" is legally protected and means the person is ARB-registered, but registration is not a legal prerequisite for designing a domestic extension.
- Is design-and-build cheaper than hiring an architect separately?
- Not automatically — but it often delivers better value on London residential projects. Because one team handles both design and construction, buildability and cost are considered from the outset rather than at tender, there is a single point of accountability, and you typically get an earlier, firmer price. The traditional architect-led route offers independent design oversight and a competitive tender, which can suit some projects better. The right choice depends on which matters more to you: design independence, or early cost certainty and single accountability.
- What are the RIBA stages and which ones do I pay for?
- The RIBA Plan of Work runs from Stage 0 to Stage 7. Homeowners usually engage an architect for Stages 1–4: brief and concept, planning, and technical/Building Regulations design. Getting to the end of planning (Stage 3) is roughly 30% of the total fee; technical design (Stage 4) is about 40%; and construction monitoring (Stages 5–6) is the final ~30%, which is optional if you appoint a contractor to manage delivery.
Sources & further reading
- HomeOwners Alliance — Architect Fees (2026)
- Architecture for London — Architects' Fees in the UK (2026 update)
- RIBA — Plan of Work (work stages)
- Architects Registration Board (ARB) — on the protected title "architect"
Figures are indicative 2026 London market ranges, cross-checked across the sources above. Always obtain written fee proposals for your specific project.