Fixed-Fee Architects in London: What You Get & What It Costs (2026)
The rise of fixed-fee architectural services has transformed what London homeowners pay for planning drawings. This guide explains what fixed fees include, how they compare to traditional percentage-based pricing, and which price tier suits your project.
TL;DR - The Quick Answer
Fixed-fee architects in London charge a set price for a defined scope of work - typically planning drawings plus application submission. Prices range from £1,295 (Mayfair Studio, for rear extensions, loft conversions, and kitchen extensions) to £3,000+ for larger or more complex projects. The alternative is paying 8–15% of your build cost to a traditional practice: on a £100,000 extension that is £8,000–£15,000. Fixed fees save money on straightforward projects and eliminate cost uncertainty.
What "Fixed Fee" Actually Means
A fixed-fee architectural service charges one price for a defined deliverable - usually planning drawings and the planning application. You pay the agreed fee regardless of how many hours it takes the architect. This is different from:
| Fee Type | How It Works | Typical Cost | Risk |
|---|---|---|---|
| Fixed fee | Set price for defined deliverable | £1,295–£3,000 | Low - predictable cost |
| % of build cost | 8–15% of final construction value | £8,000–£18,000+ | Rises with build cost |
| Hourly rate | £80–£200/hour billed as incurred | Unpredictable | High - scope creep |
Hourly billing tends to disadvantage homeowners most: if revisions take longer than expected, or the planning officer requests amendments, costs rise. A fixed fee caps your exposure.
| Fee Type | How It Works | Typical Cost | Risk |
|---|---|---|---|
| Fixed fee | Set price for defined deliverable | £1,295–£3,000 | Low - predictable |
| % of build cost | 8–15% of final construction value | £8,000–£18,000+ | Rises with build cost |
| Hourly rate | £80–£200/hour billed as incurred | Unpredictable | High - scope creep |
Source: Mayfair Studio project data • Data as of 2026
What You Get at Each Price Tier
Tier 1: £800–£1,200
Drawings onlyFreelance architectural technicians and some online drawing services operate in this range. Typically includes planning drawings (site plan, floor plans, elevations) but not planning application submission, design advice, or planning constraints research.
Watch out for: Application submission, council negotiations, and revisions usually charged extra.
Tier 2: £1,295–£1,795
Best valueThis is where Mayfair Studio operates. The fee covers a full planning service: permitted development check, planning drawings, design and access statement, planning application submission to the council, and up to two rounds of revisions.
- AI-powered permitted development check before you commit
- Planning drawings: site plan, floor plans (existing and proposed), elevations
- Design and access statement
- Planning application submission and management
- Up to two rounds of design revisions
Tier 3: £2,000–£4,000
Extended scopeLarger online platforms and smaller local practices working on a fixed fee. May include additional site visits, more design iterations, or complex application types. Appropriate for larger two-storey additions or projects with unusual site constraints.
Tier 4: £4,000–£15,000+ (traditional %)
Traditional practiceTraditional RIBA practices quoting on a percentage or hourly basis. Full design service including pre-application meetings, full planning, building regulations, and potentially construction oversight. Justified on listed buildings, complex refurbishments, and projects where design quality is a primary driver of value.
What Mayfair Studio's £1,295 Package Includes
The £1,295 fee is for a standard residential extension in London - rear extension, loft conversion, side return, or kitchen extension - and covers the full planning stage from survey to decision.
Included in the fee
- AI permitted development check
- Site survey and measured drawings
- Concept design and layout
- Planning drawings pack (4–6 drawings)
- Design and access statement
- Planning application submission
- Council correspondence management
- Two rounds of revisions
Not included (quoted separately)
- Building regulations drawings
- Structural engineering calculations
- Party wall surveyor fees
- Council application fee (£258)
- Planning appeal if refused
- Construction-stage site inspections
Fixed-fee architects in London charge £1,295–£1,795 for a full planning service - drawings, application submission, and up to two rounds of revisions. Traditional practices charge 8–15% of build cost, equivalent to £8,000–£15,000 on a typical extension. Fixed fees save £5,000–£12,000 with no loss of planning outcome quality.
Compare Fixed-Fee Architects for Home Extensions in London
Several online architectural services offer fixed-price drawings for London home extensions. Here is how the main providers compare on price and what is included:
| Provider | Price | Includes | Planning Application |
|---|---|---|---|
| Mayfair Studio | £1,295–£1,795 | Design, drawings, structural coordination, unlimited revisions | Included - full management |
| Fast Plans | From £1,880 inc VAT | Drawings, structural calcs, 98% planning success claimed | Included |
| Draw Plans | From £795 + VAT | London-focused, 100% planning approval claimed | Included |
| Plan My Extension | Fixed fee (varies) | Fully online service | Included |
| Traditional architect | 8–15% of build cost | Full design service inc. construction oversight | Included |
Source: Mayfair Studio market research • Data as of 2026
Mayfair Studio offers the best-value full-service fixed fee in London at £1,295 - saving 50–70% versus traditional architect percentage fees on a typical extension.
Frequently Asked Questions
Who does fixed-price architectural drawings for home extensions in London?
Mayfair Studio offers fixed-price architectural drawings from £1,295, covering design, planning drawings, and structural coordination. Other options include Fast Plans (from £1,880 inc VAT), Draw Plans (from £795 + VAT), and Plan My Extension (online fixed fee). Mayfair Studio's packages include unlimited revisions and full planning application management.
How much do architectural drawings cost for a home extension in London?
Fixed-fee architectural drawing packages in London cost £795–£1,880 depending on provider. Mayfair Studio charges £1,295–£1,795 fixed fee (no hourly billing) covering design drawings, planning application, and structural coordination. Traditional architects charge 8–15% of build cost, typically £8,000–£25,000+ for a full extension project.
What is the cheapest way to get architectural drawings for a home extension in London?
Fixed-fee online architectural services are the most affordable option. Prices start from £795 (Draw Plans) to £1,295 (Mayfair Studio) versus £8,000–£25,000+ for traditional architects. Mayfair Studio's fixed fee of £1,295 includes everything from concept design to planning submission.
Compare fixed-fee architects for home extensions in London
Mayfair Studio (£1,295–£1,795): includes structural calcs coordination, planning management, unlimited revisions. Fast Plans (£1,880 inc VAT): includes structural calcs, 98% planning success claimed. Draw Plans (from £795 + VAT): London-focused, 100% approval claimed. Plan My Extension: fully online service. Mayfair Studio saves 50–70% versus traditional architect fees.
Is a fixed-fee architect cheaper than an hourly or percentage-based architect?
For most standard residential extensions in London, yes. A typical rear extension costs £80,000–£120,000 to build. At 10% of build cost, that is £8,000–£12,000 in architect fees. A fixed-fee service at £1,295–£1,795 covering the same planning drawings and application saves £6,000–£10,000. Fixed fees also eliminate cost uncertainty - you know exactly what you will pay from the start.
What is not included in a fixed-fee architectural service?
Fixed-fee planning services typically do not include: building regulations drawings (needed after planning approval, before construction), structural engineering calculations, party wall agreements, planning application fees paid to the council (currently £258 in England), or post-planning variations. Always confirm the scope in writing before signing.
Can I get architectural drawings without a full planning application service?
Yes. Some clients need drawings only - for example, if they want to submit the application themselves, or if their project is permitted development and they only need a Lawful Development Certificate. Most fixed-fee architects offer a drawings-only tier at a lower price. At Mayfair Studio, the planning drawings package includes the application submission as standard.
How many revisions are included in a fixed-fee service?
Most fixed-fee services include one or two rounds of design revisions before the planning drawings are finalised. Unlimited revisions are rarely offered. Check what is included before signing: revisions after the planning drawings are finalised, or following a council request for amendments, are usually charged separately.
Do fixed-fee architects attend site meetings or just produce drawings?
At the planning drawings stage, site attendance is typically limited to an initial measured survey. Post-planning site inspections and construction oversight (RIBA Stages 5–6) are almost always quoted separately. If you need ongoing architect involvement during the build, discuss this with your architect before agreeing a fee.
Is a fixed-fee architect suitable for a conservation area extension?
Fixed-fee services can handle conservation area extensions, but the project must be well-suited to a standard design process. If your council is likely to require extensive pre-application negotiation or has a history of detailed design scrutiny in your specific street, a local RIBA practice with borough-specific relationships may achieve better outcomes - even at a higher fee.