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Kitchen Extension & Loft Conversion Costs in Bromley 2026 [VAT-Inclusive Prices]

If you own a home in the London Borough of Bromley and you are pricing a kitchen extension or loft conversion in 2026, you need numbers that reflect what local builders actually charge — not national averages that ignore the Outer London premium.

In 2026, a kitchen extension in Bromley costs £2,200–£3,800 per m² inclusive of VAT, while a loft conversion costs £1,800–£3,200 per m² inclusive of VAT, according to data from the Federation of Master Builders (FMB) and Checkatrade. For a typical 20 m² kitchen extension, that means a total project cost of £58,000–£98,000 all-in. A standard 25 m² dormer loft conversion runs £52,000–£85,000 all-in.

All prices in this guide include VAT at 20% on labour and materials unless stated otherwise. Professional fees such as planning applications and building control are typically VAT-exempt or charged at 20% depending on the supplier — always confirm with your professional.

Bromley sits in Outer London, so construction costs run 20–30% above the UK national average — lower than Zone 1–3 but still significant. The borough's mix of 1930s semi-detached homes, Victorian terraces, and post-war houses means most properties are well-suited to either a rear kitchen extension, a side-return infill, or a dormer loft conversion. But Bromley Council has strict rules on design, materials, and conservation areas that can add cost and delay if you are not prepared.

This guide gives you Bromley-specific prices, explains what Bromley Council expects from planning applications, shows what your neighbours have had approved, and reveals how to budget accurately for your project.

Get your free Bromley-specific render and cost estimate →


Table of Contents

  1. Kitchen Extension Costs in Bromley (2026)
  2. Loft Conversion Costs in Bromley (2026)
  3. What Affects Your Cost in Bromley
  4. Bromley Council Planning Permission: What You Need to Know
  5. Hidden Costs You Should Budget For
  6. How to Save Money on Your Bromley Extension
  7. What the Neighbours Got Approved
  8. How Suddeco Homes Helps
  9. Frequently Asked Questions

Kitchen Extension Costs in Bromley (2026)

Kitchen extensions are the most popular renovation project in Bromley. The borough's large gardens — especially in Bickley, Chislehurst, and Orpington — make rear extensions attractive. Victorian terraces in Beckenham and Shortlands often suit side-return infills.

Cost per m² by Project Type

Project Type Low Cost (inc. VAT) Average Cost (inc. VAT) High Cost (inc. VAT) Notes
Small rear kitchen extension (15 m²) £33,000 £45,000 £57,000 Standard finish, simple rectangular footprint
Medium rear kitchen extension (25 m²) £55,000 £75,000 £95,000 Mid-range finish, some glazing
Side-return kitchen extension (10 m²) £26,000 £32,000 £42,000 Narrow infill, mid-range finish
Wrap-around extension (30 m²) £72,000 £96,000 £126,000 Rear + side return, premium finish
Double-storey extension (35 m² total) £77,000 £105,000 £133,000 Ground-floor kitchen + first-floor bedroom
Per m² (all types) £2,200 £3,000 £3,800 Includes Outer London labour premium

Sources: Checkatrade 2026 Cost Guides; FMB regional pricing data for Outer London; HomeOwners Alliance renovation reports. All construction and labour costs include VAT at 20%.

What Is Included in the Construction Cost per m²

What Is NOT Included (Budget Separately)

Item Cost Range (inc. VAT where applicable) Notes
Kitchen units and appliances £8,000–£30,000+ Budget £400–£1,000 per m² of kitchen space
Tiling (floor and walls) £1,500–£5,000 Premium tiles and mosaic work cost more
Worktops £1,500–£5,000 Laminate is cheap; quartz, granite, and Dekton are premium
Glazing upgrades (bi-folds, roof lantern) £2,000–£8,000 Often the biggest single upgrade cost
Underfloor heating £1,500–£4,000 Electric mats are cheaper; wet systems are more efficient
Structural engineer £500–£2,000 20% VAT applicable
Architect / designer £3,750–£7,500 5–10% of construction cost; 20% VAT applicable
Planning permission (householder) £206 VAT-exempt
Building regulations £200–£1,000 VAT-exempt or 20% depending on provider
Party wall surveyor £700–£2,000 20% VAT applicable
Site clearance and preparation £500–£3,000 Removing old structures, trees, or difficult access
External works (patio, drainage) £2,000–£8,000 Connecting drains, laying patios, landscaping
Contingency 10–15% of total budget Essential buffer for unexpected issues

All-in cost per m² for a mid-range kitchen extension in Bromley: Budget £3,200–£4,800 per m² when you include kitchen fit-out, professional fees, and contingency.


Loft Conversion Costs in Bromley (2026)

Loft conversions are one of the highest-ROI improvements in Bromley. The borough's high proportion of 1930s semi-detached and detached homes with hipped roofs makes hip-to-gable and dormer conversions particularly popular.

Cost per m² by Conversion Type

Project Type Low Cost (inc. VAT) Average Cost (inc. VAT) High Cost (inc. VAT) Notes
Velux / rooflight conversion (20 m²) £36,000 £48,000 £64,000 Lightest intervention, two windows, standard finish
Dormer conversion (25 m²) £45,000 £65,000 £85,000 Full-width dormer, mid-range finish
Hip-to-gable conversion (30 m²) £54,000 £78,000 £102,000 Changes roof shape, more space, standard finish
Mansard conversion (35 m²) £63,000 £91,000 £119,000 Maximum headroom, premium finish
Shell-only conversion (20 m²) £30,000 £42,000 £54,000 Structural work, insulation, electrics — interior fit-out excluded
Per m² (all types) £1,800 £2,600 £3,200 Includes Outer London labour premium

Sources: Checkatrade 2026 Cost Guides; FMB regional pricing data for Outer London.

What Is Included in the Construction Cost per m²

What Is NOT Included (Budget Separately)

Item Cost Range (inc. VAT where applicable) Notes
En-suite bathroom £5,000–£12,000 Plumbing route and soil pipe access are key cost drivers
Bespoke joinery / fitted storage £3,000–£10,000 Built-in wardrobes, eaves storage, shelving
Premium flooring £2,000–£6,000 Engineered oak, carpet, underfloor heating
Structural engineer £500–£2,000 20% VAT applicable
Architect / designer £3,750–£7,500 5–10% of construction cost; 20% VAT applicable
Planning permission (if required) £206–£462 VAT-exempt
Building regulations £200–£1,000 VAT-exempt or 20% depending on provider
Party wall surveyor £700–£2,000 20% VAT applicable
Scaffolding £1,000–£3,000 20% VAT included
Contingency 10–15% of total budget Essential for rot, asbestos, or structural surprises

All-in cost per m² for a mid-range loft conversion in Bromley: Budget £2,600–£3,800 per m² when you include bathroom fit-out, professional fees, and contingency.


What Affects Your Cost in Bromley

1. Property Type and Era

Bromley's housing stock varies significantly by area, and the type of home you own has a direct impact on cost:

Property Type Common Area Best Extension Type Cost Impact
1930s semi-detached Bickley, Chislehurst, West Wickham Hip-to-gable loft conversion or rear extension Standard — good access, straightforward structure
Victorian terrace Beckenham, Shortlands, Bromley town Side-return infill or dormer loft conversion +10–15% for narrow access, party wall complexity
Post-war house Orpington, Penge, Anerley Rear extension or Velux loft conversion Standard — often simpler construction
Detached (various eras) Chislehurst, Orpington Wrap-around or large rear extension, mansard loft Higher total cost but efficient per m²

2. Access and Site Constraints

3. Conservation Areas and Listed Buildings

Bromley has over 30 conservation areas, including Chislehurst, Bromley Palace Park, parts of Beckenham, and Shortlands. If your property is within a conservation area or is listed, permitted development rights are restricted:

Suddeco tip: Enter your Bromley address on our platform and we will instantly check whether your property falls within a conservation area or has an Article 4 direction. Try it free →

4. Finish Level

Level Kitchen Extension £/m² Loft Conversion £/m² Typical Specification
Budget £2,200–£2,600 £1,800–£2,200 Standard materials, basic fittings, minimal glazing
Mid-range £2,600–£3,200 £2,200–£2,800 Quality materials, good kitchen, some bi-folds or roof lantern, engineered stone worktops
Premium £3,200–£3,800+ £2,800–£3,200+ Bespoke kitchen, extensive glazing, underfloor heating, smart home integration, premium flooring

5. Structural Complexity


Bromley Council Planning Permission: What You Need to Know

Permitted Development (PD) Rights

Many kitchen extensions and loft conversions in Bromley fall under permitted development, meaning no full planning application is needed if you meet these criteria:

For single-storey rear extensions: - Maximum depth: 4 m (detached) or 3 m (attached/terraced) from the original rear wall - Maximum height: 4 m - Materials must be similar in appearance to the existing house - Not on designated land (conservation areas, AONBs, Article 4 areas) unless the extension is under 6 m (detached) or 3 m (other)

For loft conversions: - Must not exceed the height of the existing roof - Must not extend beyond the plane of the existing roof slope at the front - Side-facing windows must be obscure-glazed and non-opening (or open above 1.7 m) - No verandas, balconies, or raised platforms - Volume addition limited to 40 m³ (terraced) or 50 m³ (detached/semi)

Important: Even if your project falls under permitted development, a Lawful Development Certificate (£103) is strongly recommended. It provides proof of compliance — essential when selling your home.

When You Need Full Planning Permission in Bromley

Bromley Council's planning department typically takes 8–12 weeks to determine a householder application. Pre-application advice costs £150–£300 and can save months of resubmissions.

Building Regulations

All kitchen extensions and loft conversions must comply with Building Regulations, covering: - Structural integrity - Thermal insulation (U-values) - Fire safety - Ventilation - Drainage

You will need either a Building Notice or Full Plans Approval. Cost: £200–£1,000 depending on your chosen building control provider. Bromley Council offers its own building control service, or you can use an approved private inspector.

Our Design+Planning package includes the planning application, building regulations, structural engineer calculations, and unlimited revisions — all for a fixed fee of £2,495.


Hidden Costs You Should Budget For

Many homeowners focus on the build cost and forget the extras. These add up quickly in Bromley. Note: professional fees listed below are typically VAT-exempt or charged at 20% depending on the supplier — always confirm with your professional.

Cost Item Typical Price Range VAT Status
Planning permission (householder) £206 Exempt
Planning permission (full application) £462 Exempt
Lawful Development Certificate £103 Exempt
Building regulations approval £200–£1,000 Exempt or 20%
Party wall agreement £700–£2,000 20% VAT applicable
Structural engineer £500–£2,000 20% VAT applicable
Architect fees (traditional) 5–10% of build cost 20% VAT applicable
Tree survey (if TPO applies) £300–£800 20% VAT applicable
Contingency fund 10–15% of total budget Included in build VAT
Scaffolding £1,000–£3,000 20% VAT included
Building control inspection £300–£700 Exempt or 20%
Temporary relocation (if needed) £500–£2,000 N/A

A sensible approach is to add 15–20% on top of your quoted build cost to cover fees, contingencies, and unexpected issues like rot, asbestos discovery, or concealed drainage.

Sources: HomeOwners Alliance Cost Guide; Planning Portal Fee Schedule 2026; Bromley Council planning and building control fee schedules.


How to Save Money on Your Bromley Extension

1. Use Permitted Development Rights

If your project falls within permitted development, you avoid the £206–£462 planning fee and 8–12 weeks of waiting. Our platform checks your Bromley address against local authority data instantly. Try your free render →

2. Get Your Design Right First Time

Reworking plans after construction starts is the fastest way to blow your budget. Changes on site can cost 20–40% more than the same work designed in advance. Our AI generates accurate, planning-ready designs with fixed pricing — no surprise architect fees, no revision charges.

3. Choose the Right Suddeco Package

Package Price Best For
Free Render £0 Visualising what is possible, getting an address-specific cost estimate
Concept £495–£995 3 renders, full plans, one revision, 48-hour delivery
Design+Planning £2,495 Planning application, building regs, structural engineer, unlimited revisions
Design-to-Build Fee + % of build cost Vetted builders, project management, milestone payment protection, 12-month warranty

4. Time Your Build

Bromley builders are busiest March–September. Booking January–February or October–November can secure 5–10% discounts on labour. Avoid starting in December — short days and holiday closures extend timelines.

5. Keep the Layout Simple

Every corner, steel beam, and bespoke angle adds cost. A rectangular box with a standard pitch roof is the most cost-effective design. Let your kitchen designer add character through fittings and finishes rather than architecture.

6. Reuse and Match Existing Materials

Bromley Council often requires extensions to match the existing house. Salvaging original bricks, roof tiles, and floorboards is cheaper than buying new heritage-style products — and it satisfies planners.

7. Consider a Shell-Only Loft Conversion

A shell-only conversion includes structural work, insulation, electrics, and basic plastering, but leaves the interior fitting to you. This can reduce the upfront cost by 20–30% and lets you spread spending over time.


What the Neighbours Got Approved

Our AI analyses thousands of approved planning applications across Bromley. Here are recent examples from real streets:

Example 1: Westmoreland Road, Bromley, BR1

Example 2: Durham Avenue, Bromley, BR2

Example 3: Manor Road, Chislehurst, BR7

Example 4: Hayes Lane, Bromley, BR2

See what your Bromley neighbours got approved — free instant render →


How Suddeco Homes Helps

Traditional renovation projects involve months of back-and-forth with architects, weeks waiting for quotes, and uncertainty about what Bromley Council will actually approve. Our platform changes that.

Step 1: Enter your Bromley address. Our AI analyses nearby approved planning applications to understand what Bromley Council has already permitted on similar homes in your area.

Step 2: Receive an instant render, floor plans, and a cost estimate — completely free. No appointment, no waiting, no commitment.

Step 3: Choose your package. Our Concept Package delivers three renders, full plans, and one revision within 48 hours for £495–£995. Our Design+Planning package handles the full planning application, building regulations, and structural engineering for £2,495.

Step 4: Build with confidence. Our Design-to-Build service matches you with vetted builders who know Bromley, includes project management, milestone payment protection, and a 12-month warranty.

Get your free Bromley kitchen extension or loft conversion render today →


Frequently Asked Questions

How much does a kitchen extension cost in Bromley in 2026?

In 2026, a kitchen extension in Bromley costs £2,200–£3,800 per m² for construction, inclusive of VAT at 20%. A typical 20 m² rear extension averages £60,000 for construction alone, or £90,000 all-in including kitchen fit-out, fees, and contingency. The Outer London premium means Bromley prices are 20–30% above the UK national average.

How much does a loft conversion cost in Bromley in 2026?

A loft conversion in Bromley costs £1,800–£3,200 per m² for construction, inclusive of VAT at 20%. A standard 25 m² dormer conversion averages £65,000 for construction, or £85,000–£95,000 all-in. Velux conversions are cheaper (£36,000–£48,000), while mansard conversions are premium (£63,000–£119,000).

Do I need planning permission for a kitchen extension in Bromley?

Not always. Many single-storey rear extensions up to 4 m (detached) or 3 m (attached/terraced) fall under permitted development. However, if you are in a conservation area (Chislehurst, parts of Beckenham, Bromley Palace Park, Shortlands), a listed building, or exceeding size limits, full planning permission is required. Our platform checks your Bromley address instantly. Try it free →

Do I need planning permission for a loft conversion in Bromley?

Most loft conversions are permitted development if they do not exceed the existing roof height, use similar materials, and stay within volume limits (40 m³ for terraced, 50 m³ for detached/semi). However, dormer conversions in conservation areas or listed buildings always require full planning permission. Check with Bromley Council before starting.

How long does a kitchen extension take in Bromley?

A typical single-storey kitchen extension takes 8–14 weeks to build. Planning permission adds 8–12 weeks if required. Design and preparation (surveys, structural calculations) take 2–4 weeks. Total timeline: 4–7 months from design to completion.

How long does a loft conversion take in Bromley?

A standard dormer loft conversion takes 8–12 weeks to build. Velux conversions are faster (6–8 weeks). Mansard and hip-to-gable conversions take 10–14 weeks. Planning adds 8–12 weeks if required. Total timeline: 3–6 months.

What is the London premium on construction costs in Bromley?

Bromley sits in Outer London, so construction costs are 20–30% higher than the UK national average. This is lower than Central London (Zone 1–2 at +40–50%) but still significant. Labour, material delivery, parking, and access constraints all contribute.

What is the cheapest way to extend a kitchen in Bromley?

The cheapest kitchen extension is a small single-storey rear extension under permitted development using standard materials and a simple rectangular design. Avoid structural complexity, bespoke angles, and premium finishes. Book builders in off-peak months (Jan–Feb or Oct–Nov) for potential 5–10% discounts.

Does a loft conversion add value in Bromley?

Yes. A well-executed loft conversion typically adds 15–20% to your property value. With Bromley's average house price at approximately £550,000–£650,000 (depending on area), this can mean £80,000–£130,000 in added equity — often more than the cost of the conversion itself.

Can I see what my Bromley neighbours have built?

Yes. Suddeco's AI reads your address and shows nearby approved planning applications in Bromley, including designs, dimensions, and outcomes. This helps you understand what Bromley Council approves and what your neighbours have achieved. Get your free instant render →

What is included in Suddeco's £2,495 Design+Planning package?

The Design+Planning package includes: full architectural plans, 3D renders, planning application submission to Bromley Council, building regulations drawings, structural engineer calculations, and unlimited revisions. Everything you need to get planning approval and start building.

How does Suddeco's free render work?

Enter your Bromley address on our platform. Our AI analyses nearby planning precedents and generates an instant render of what is possible for your property, plus rough plans and a cost estimate. No credit card required. Try it now →

How much does a side-return extension cost in Bromley?

A side-return kitchen extension in Bromley typically costs £2,600–£3,500 per m² (inc. VAT), or £32,000–£42,000 for a 10–12 m² infill. The per-m² cost is higher than a rear extension because of narrow access, party wall complexity, and rerouting drains and services — but the total cost is often lower because the area is smaller.

What are the main conservation areas in Bromley that affect planning?

Bromley has over 30 conservation areas. The most impactful for homeowners include: Chislehurst (strict material and design controls), Bromley Palace Park, Shortlands, parts of Beckenham (especially near St George's Church and the village centre), and Orpington Priory. Always check whether your property falls within a conservation area before assuming permitted development applies.

Is VAT included in Bromley extension prices?

Yes. All construction and labour costs in this guide include VAT at 20%. Some builders quote net of VAT and add it later — always confirm whether your quote is inclusive or exclusive. Professional fees (planning applications, building control) are typically VAT-exempt, while architect, engineer, and surveyor fees usually attract 20% VAT.

Can I get a kitchen extension or loft conversion under £50,000 in Bromley?

A small Velux loft conversion or a very basic kitchen side-return extension in Bromley might come in around £45,000–£55,000 all-in, but this requires careful budget management, standard materials, and minimal structural complexity. Be wary of quotes significantly below market rate — they often exclude essential elements, VAT, or use unqualified labour.

What is the difference between a dormer and a mansard loft conversion?

A dormer has a flat-roofed extension projecting from the existing sloped roof, creating vertical walls and full headroom. A mansard replaces the entire roof slope with a steep, near-vertical wall and flat roof. Mansards offer more space but cost 20–30% more and usually require planning permission. Dormers are more common in Bromley because they are simpler and often fall under permitted development.

Do I need a party wall agreement in Bromley?

If your property is attached or semi-detached and your extension or loft conversion involves work on a shared wall, excavating within 3 m of a neighbour's foundations, or cutting into a party wall, you will need a party wall agreement under the Party Wall etc. Act 1996. This costs £700–£2,000 (inc. VAT) per neighbour and typically takes 4–8 weeks to agree. Factor this into your timeline.



Last updated: 9 July 2026. Cost figures are based on industry data from Checkatrade, the Federation of Master Builders, and the HomeOwners Alliance, adjusted for inflation, 2026 market conditions, and the Outer London labour premium. All construction and labour prices include VAT at 20% unless stated otherwise. Professional fees are typically VAT-exempt or charged at 20% depending on the supplier — always confirm. Cost per m² is an average and actual prices vary by location, specification, and contractor. Always obtain detailed quotes before committing to a project.



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