Resi vs Mayfair Studio: Which Online Architect Is Right for Your London Extension? (2026)
Resi is the UK's best-known online architectural design service. Mayfair Studio is a London-specialist alternative. Here's an honest comparison - prices, inclusions, and which suits different projects.
TL;DR - The Quick Answer
Resi is a well-established UK-wide online architectural design service with a larger team and strong track record. Mayfair Studio is a London-specialist alternative with a single all-in fixed fee. On price, Mayfair Studio is typically the cheaper option once structural engineering is factored in: Resi's ground-floor-only Express package starts at £1,500 but prices structural engineering separately (typically £600-£1,500 extra), and its Explore package for lofts and two-storey extensions starts at £3,000, also before structural costs. Mayfair Studio's £1,880 all-in fee already includes structural engineer calculations, planning application submission, and building regulations drawings, with unlimited revisions and a price match guarantee. Resi's advantage is its larger operation, broader UK coverage, and vetted builder introductions. If you're extending a London home and want a known, capped price from the outset, Mayfair Studio at £1,880 all-in is worth considering first.
Resi vs Mayfair Studio: Side-by-Side Comparison
| Mayfair Studio | Resi | |
|---|---|---|
| Starting price | £1,880 all-in | Express (ground floor only) from £1,500 / Explore (most extensions) from £3,000 |
| London-specialist? | Yes - London only | UK-wide |
| Structural calcs included in fee? | Yes | No - quoted separately by engineers |
| Planning application included? | Yes | Yes |
| Turnaround | First drawings within 2 weeks (no survey wait) | Express ~4 weeks / Explore ~6 weeks to planning submission |
| Revisions policy | Unlimited | 3 rounds (Elevate tier: unlimited) |
| Conservation area experience? | Extensive (London) | Good (UK-wide) |
| Free initial check? | Yes (AI chat) | Initial consultation |
Source: Mayfair Studio and publicly available Resi pricing information • Data as of 2026
Prices are approximate and Resi's published tiers can change. Resi's Express package (from £1,500) covers ground-floor extensions only, with structural engineering arranged via a choice of separately-quoted engineers rather than bundled into the design fee. Its Explore package (from £3,000) covers most other extension types, including lofts and two-storey extensions, again with structural engineering quoted separately. Always confirm current pricing directly with each provider. Mayfair Studio's £1,880 all-in fixed fee applies to any standard loft conversion or extension and already includes structural engineer calculations, planning application submission, and building regulations drawings.
Both services use technology to streamline the process compared to traditional high-street architects. Neither requires you to visit an office. Both handle the planning process end-to-end.
Other Alternatives to Resi for London Extensions
Beyond Mayfair Studio and Resi, there are a handful of other online architectural drawing services worth knowing about:
| Service | Starting Price | Coverage | Notes |
|---|---|---|---|
| Mayfair Studio | £1,880 all-in | London | All-in fixed fee, structural calcs included, planning included |
| Resi | Express from £1,500 / Explore from £3,000 | UK-wide | Largest online architect, strong track record; structural engineering quoted separately |
| Draw Plans | From £750 | UK-wide | Drawings only - structural and planning extra |
| Plan My Extension | From £595 | UK-wide | Entry-level plans; may need additional services |
Source: Publicly available pricing information • Data as of 2026
Draw Plans and Plan My Extension offer lower entry prices but typically do not include structural calculations or planning applications - you'd need to source these separately, which can add £2,000–£5,000 to total costs. Resi's own Express and Explore packages include planning support but likewise price structural engineering separately (typically £600-£1,500), which pushes their like-for-like total above Mayfair Studio's £1,880 capped fee for most project types. Mayfair Studio's all-in price at £1,880, calcs included, often represents better total value.
What's Included at Each Price Point
Mayfair Studio - £1,880 All-in Fixed Fee
- Measured survey of your property
- Existing and proposed floor plans, elevations, and sections
- Structural engineer calculations (often billed separately elsewhere)
- Planning application preparation and submission
- Building Control drawings for construction
- Unlimited design revisions, plus free council amendments and free resubmission if needed
- Party wall notices and a dedicated project manager throughout
- Price match guarantee on like-for-like scope for standard residential projects
Resi - Three Pricing Tiers
Resi's headline prices are "from" figures that depend on which tier your project needs:
- Express (from £1,500) - ground-floor extensions only. Structural engineering is arranged through Resi's matched-builder route, not bundled into the design fee.
- Explore (from £3,000) - covers most other extension types, including lofts and two-storey extensions. Structural engineering is a "choice of structural engineering quotes" - i.e. quoted separately by engineers, an additional cost on top.
- Elevate (bespoke pricing) - for complex or larger projects, quoted individually.
- All tiers include survey, design, planning support, standard building regs drawings, and vetted builder introductions.
The main practical difference: Mayfair Studio's £1,880 is a single capped fee with structural calculations built in, for any standard loft conversion or extension. Resi's fees are "from" prices that vary by tier and rise once structural engineering is quoted - on lofts and two-storey extensions specifically, Resi's Explore tier starts at £3,000 before structural costs, well above Mayfair Studio's £1,880 all-in. Even on a ground-floor extension under Resi's cheapest Express tier, adding a typical £600-£1,500 structural engineering quote brings the like-for-like total to roughly £2,100-£3,000 - still above Mayfair Studio's capped fee. Resi remains a larger operation with broader UK coverage and vetted builder introductions.
Which Should You Choose?
| Your Situation | Better Option |
|---|---|
| London extension, budget-conscious | Mayfair Studio (£1,880 all-in) |
| London extension, conservation area | Mayfair Studio (London specialism) |
| Extension outside London | Resi |
| Want the largest, most established service | Resi |
| Want a known, capped all-in price upfront | Mayfair Studio |
| Loft conversion or two-storey extension | Mayfair Studio (£1,880 all-in vs Resi Explore from £3,000 + structural) |
| Ground-floor extension, want the lowest headline price | Resi Express (from £1,500, before structural engineering) |
| Need interior design services too | Resi (broader service range) |
| Just need drawings (no planning) | Draw Plans or Plan My Extension |
About Mayfair Studio
Mayfair Studio is a London-specialist architectural service covering all 33 London boroughs. We focus exclusively on London residential extensions - rear extensions, loft conversions, side returns, and two-storey extensions. Our fixed-fee service at £1,880 all-in includes planning drawings, structural calculations, planning application submission, and building control drawings.
Our AI chat tool is free to use and gives instant permitted development checks and cost estimates for your specific London address - no contact details required.
Mayfair Studio charges £1,880 all-in for any standard London loft conversion or extension, including planning drawings, structural engineer calculations, and planning application submission - a single capped fee. Resi's comparable tier for lofts and two-storey extensions, Explore, starts at £3,000 before structural engineering is quoted separately; even Resi's cheapest tier, Express (£1,500, ground-floor extensions only), typically reaches £2,100-£3,000 once a separately-quoted structural engineer is added. Mayfair Studio is London-specialist; Resi covers the whole UK and offers a larger team and vetted builder introductions. For London homeowners wanting cost certainty from the outset, Mayfair Studio typically works out cheaper on a like-for-like basis.
Frequently Asked Questions
Is there a cheaper alternative to Resi for home extensions in London?
For most project types, yes. Mayfair Studio charges £1,880 all-in for any standard loft conversion or extension in London, with structural engineer calculations included. Resi's comparable tier, Explore (lofts, two-storey extensions and most other types), starts at £3,000 before structural engineering, which is quoted separately by engineers. Even Resi's cheapest tier, Express (£1,500, ground-floor extensions only), typically reaches £2,100-£3,000 once a separately-quoted structural engineer is added - above Mayfair Studio's capped fee. Mayfair Studio is London-specialist (covering all 33 boroughs) while Resi operates UK-wide. Other alternatives include Draw Plans and Plan My Extension, which offer lower headline prices but typically don't include planning applications or structural calculations at all.
Resi vs Mayfair Studio: which is better for London extensions?
For most London extensions, particularly lofts and two-storey extensions, Mayfair Studio is the cheaper option: a £1,880 all-in fixed fee with structural calculations included, versus Resi's Explore tier from £3,000 before structural engineering is quoted separately. Mayfair Studio is London-specialist and includes planning drawings, structural calculations, and planning applications in one capped fee. Resi has a larger team and covers the whole UK, which is an advantage if you're outside London or want vetted builder introductions as part of the package. Both manage the planning process end-to-end.
How much does Resi charge for a home extension?
Resi has three pricing tiers. Express starts at £1,500 but covers ground-floor extensions only, with structural engineering arranged separately via Resi's matched-builder route. Explore starts at £3,000 and covers most other extension types, including lofts and two-storey extensions, with structural engineering quoted separately by engineers as an additional cost. Elevate is bespoke pricing for complex projects. All tiers include survey, design, planning support, and standard building regulations drawings. For comparison, Mayfair Studio charges a single fixed fee of £1,880 all-in for London extensions, with structural engineer calculations included in that price. Always confirm current pricing directly with Resi for your specific project.
What are the best alternatives to Resi for architectural drawings in London?
The best alternatives to Resi for London home extensions are: Mayfair Studio (£1,880 all-in, London-specialist, structural calculations and planning included in one capped fee), Draw Plans (from £750 for drawings only - structural and planning extra), and Plan My Extension (from £595 entry-level, additional services usually needed). For lofts and two-storey extensions specifically, Mayfair Studio is typically the cheaper full-service option versus Resi's Explore tier (from £3,000 before structural engineering).
Is Mayfair Studio cheaper than Resi?
For most project types, yes. Mayfair Studio charges a fixed fee of £1,880 all-in for London home extensions, including structural engineer calculations. Resi's comparable tier for lofts and two-storey extensions, Explore, starts at £3,000 before structural engineering is quoted separately by engineers, and even Resi's cheapest Express tier (£1,500, ground-floor extensions only) typically reaches £2,100-£3,000 once structural costs are added. Mayfair Studio's price is capped and comes with a price match guarantee; Resi's tiered prices are starting points that rise with scope. Resi remains a larger, UK-wide operation with a strong track record.