London Extension & Planning Advice
Expert guidance on London home extensions, planning permission, costs, and building regulations. Written by architects with data from 80+ completed projects.
Resi vs Mayfair Studio: Which Online Architect for London Extensions? (2026)
Honest comparison of Resi and Mayfair Studio for London home extensions. Prices from £1,295 vs £1,500+, what's included, turnaround times, and which suits your project.
Loft Conversion vs Rear Extension London (2026): Costs, Planning & Which to Choose
Loft conversion or rear extension? Full comparison: costs (£54k–£75k vs £40k–£65k), PD eligibility, value added, build times, and which suits your property.
Extension Costs by London Borough 2026: Where Is It Cheapest to Build?
Compare extension costs across 15 London boroughs. Cost per m², conservation area risk, Article 4 zones, and planning approval rates - from £1,900/m² (Lewisham) to £3,800/m² (Kensington & Chelsea).
Do I Need Planning Permission for My Extension in London? (2026)
Decision framework for London homeowners. PD rules by extension type, conservation areas, Article 4 directions, and free instant check tool.
Maximum Extension Size Without Planning Permission in London (2026)
Exact PD size limits for every extension type - rear extensions, lofts, side extensions. Plus the Prior Approval scheme that allows 6m or 8m rear extensions without a planning application.
Best Architects for Home Extensions in London (2026 Guide)
Ranked guide to the best architects for London home extensions. Mayfair Studio fixed fees from £1,295 vs local RIBA practices (8–15%), Resi, and freelance technicians - with comparison table.
Fixed-Fee Architects in London: What You Get & What It Costs (2026)
Fixed-fee architect costs in London 2026. Price tiers from £1,295, what each tier includes, and how fixed fees compare to hourly (£80–200/hr) and percentage-based (8–15%) charging.
Do I Need an Architect for a Home Extension in London?
No legal requirement - but here is the practical case. When professional drawings are essential, what happens when homeowners skip them, and how fixed-fee services from £1,295 cover everything you need.
How Much Do Architectural Drawings Cost in London? (2026)
Planning drawings £1,295–£3,000, building regs £1,500–£4,000, structural engineering £600–£1,500. Cost breakdown by drawing type, factors affecting price, and fixed fee vs hourly comparison.
How to Get Planning Permission for a Home Extension in London (2026 Step-by-Step Guide)
Complete 7-step guide to planning permission for London extensions. Council fee £258, 8-week decision period, timeline table, common refusal reasons, and total cost breakdown.
Two Storey Extension London 2026: Costs, Planning & Design Guide
Complete guide to two storey extensions in London 2026. Costs £72k-£220k inc VAT. Planning permission almost always required. Cheaper per m² than single storey. 14-20 months from start to finish.
Party Wall Agreement London 2026: Costs, Process & Surveyor Fees
Complete guide to party wall agreements in London 2026. Surveyor fees £750–£1,800 per neighbour (you pay both). Process takes 2–4 months. Required for ~95% of London extensions.
Extension Size Cost Guide London 2026: 3m, 4m, 5m & 6m Prices
How much does a 3m x 5m extension cost in London? Full size-by-size breakdown inc VAT. 3mx5m £45k-£70k, 4mx5m £60k-£92k, 6mx6m £108k-£165k. Planning rules by depth included.
London Extension Costs 2026: Complete Pricing Guide
Updated 2026 extension costs from real London projects. £3,200-£4,600 per m², single-storey £60k-135k, two-storey £110k-290k. Borough breakdowns and cost calculator.
Side Return Extension London 2026: Costs, Planning & Design Guide
Side return extension costs London 2026 inc VAT: 1.2m×8m £52k–£90k structure, £70k–£130k all-in with kitchen and fees. Planning rules, RSJ beam costs, glass roof options and full 8–12 month timeline.
Extension Project Checklist 2025: Complete Step-by-Step Guide
Complete checklist for your London extension project. From initial ideas through to completion, every step you need to follow for a successful build.
Open Plan Kitchen Extension London 2025: Design, Costs & Layout Ideas
Complete guide to open plan kitchen extensions in London. Layout options, zoning strategies, structural considerations, and design tips for modern living.
Extension Lighting Design 2025: Natural Light, LEDs & Planning
Complete guide to lighting your extension. Natural light strategies, LED layouts, Part L requirements, and how to create the perfect atmosphere.
Structural Engineer Guide London 2025: When You Need One & Costs
Complete guide to structural engineers for London extensions. When you need one, what they do, typical costs £500-£2,000, and how to find a good one.
DIY vs Professional Extensions: What Can You Do Yourself in London?
Should you DIY your extension or hire professionals? Which tasks you can legally do yourself, what requires qualified tradespeople, and how to save money safely.
Prior Approval London 2025: When You Need It & How to Apply
Complete guide to prior approval in London. Larger home extensions, office to residential conversions, and other developments that need council notification.
How to Choose a Builder London 2025: Vetting, Contracts & Red Flags
Complete guide to finding and vetting builders in London. Get quotes, check references, understand contracts, and avoid cowboys. Protect your extension project.
Energy Efficient Extensions London 2026: Part L, Insulation & Heat Pumps
Part L 2021 U-values for extensions: walls 0.18 W/m²K, roof 0.15 W/m²K. Part O overheating rules, £7,500 heat pump grant, underfloor heating costs, solar PV payback and EPC improvement guide.
Energy Efficient Extensions London 2025: Part L, EPC & Sustainability
Build a sustainable extension in London. Part L 2021 requirements, EPC improvements, heat pumps, insulation standards, and how to reduce running costs.
Adding a Bathroom to Your Extension London 2025: Costs & Value Guide
Complete guide to adding bathrooms in London extensions. Ensuite costs £8,000-£15,000, adds 4-5% to property value. Plumbing, planning, and design considerations.
Basement Extension London 2026: Costs, Planning & Construction Guide
Basement extension costs London 2026 inc VAT: new basement £130k–£700k+, cellar conversion £30k–£90k. Borough planning policies, underpinning methods, waterproofing types and full 14–22 month timeline.
Garage Conversion London 2026: Costs, Planning & Complete Guide
Garage conversion costs London 2026 inc VAT: basic £18k–£30k, bedroom with en-suite £32k–£50k, full annex £40k–£70k. Planning rules, building regulations, and what use gives the best return.
Garage Conversion London 2025: Costs, Planning & Complete Guide
Complete guide to garage conversions in London. Costs from £15,000-£45,000, planning rules, building regulations, and how to maximise value. 4-8 week build time.
Greenwich Planning Refusals: Top 10 Reasons & How to Avoid Them
Data analysis of Greenwich planning refusals reveals 10 most common rejection reasons. 32% approval rate in conservation areas vs 68% elsewhere. Expert tips to avoid refusal.
Croydon Planning Refusals: Top 10 Reasons & How to Avoid Them
Data analysis of Croydon planning refusals reveals 10 most common rejection reasons. Suburban character issues account for 38%. Expert tips to avoid refusal.
Top 10 Fire Safety Consultants London 2025
Ranked list of London fire safety consultants for home extensions. Fire strategy reports from £350. Essential for loft conversions, open plan layouts, and Building Regs compliance.
Enfield Planning Refusals: Top 10 Reasons & How to Avoid Them
Data analysis of Enfield planning refusals reveals 10 most common rejection reasons. 24% relate to Green Belt, terracing effect issues account for 19%. Expert tips to avoid refusal.
Hammersmith & Fulham Planning Refusals: Top 10 Reasons & How to Avoid Them
Data analysis of H&F planning refusals reveals 10 most common rejection reasons. 67% conservation area coverage, Victorian terrace issues dominate. Expert tips to avoid refusal.
Newham Planning Refusals: Top 10 Reasons & How to Avoid Them
Data analysis of Newham planning refusals reveals 10 most common rejection reasons. Olympic regeneration zones, Victorian terraces. 92% prior approval success rate.
Top 10 Tree & Ecology Consultants London 2025
Ranked list of London arboriculturists and ecologists for home extensions. BS5837 surveys from £350. Essential for TPO trees, bat surveys, and planning compliance.
Top 10 Drainage Consultants London 2025
Ranked list of London drainage consultants for home extensions. Thames Water Build Over agreements, CCTV surveys from £250, soakaway design specialists.
Top 10 Traffic Consultants London 2025
Ranked list of London traffic consultants for home extensions. Transport statements, parking surveys, Construction Management Plans from £350.
Top Construction Challenges for London Home Extensions in 2025
Navigate the biggest obstacles facing London homeowners in 2025. Labour shortages, material costs up 12%, planning delays, and new building regulations explained.
Southwark Extension Guide: Planning, Costs & Conservation Areas 2025
48 conservation areas in Southwark. Side return £80k-120k, rear £70k-105k. Dulwich, Peckham, Camberwell planning. Victorian terraced costs.
Greenwich Extension Guide: Planning, Costs & World Heritage Site 2025
Maritime Greenwich World Heritage Site restrictions. 20 conservation areas. Side return £55k-90k, rear £65k-95k. Victorian/Edwardian terraced costs.
Islington Extension Guide: Planning, Costs & Rules 2025
40/42 conservation areas restrict permitted development. Side return £50k-110k, rear £60k-90k. Article 4 directions extensive. Typical terraced house extension costs.
Asbestos in London Extensions: Survey, Removal & Costs 2025
Pre-2000 houses 80% likely to contain asbestos. Survey £250-500, removal £1,500-3,500. Artex, floor tiles, roof sheets. HSE licensed contractor requirements.
Flat Roof vs Pitched Roof Extension London 2025
Flat roof £52k vs pitched £60k for 30m² extension. Flat: cheaper, easier permitted development, 20-year lifespan. Pitched: 50-90 years, less maintenance, better resale.
Extension Rejected? Planning Appeals Guide London 2025
34% success rate for householder appeals (2025 data). Written representation vs hearing costs, 10-16 week timelines, when to appeal. Real London examples.
Narrow Garden Extension London: Solutions for Small Gardens
Narrow garden extension solutions: 3-6m depth options, vertical design, minimal garden loss. 10-15m² extensions £35k-£60k.
Single vs Double Storey Extension London 2026: Which Is Better?
Single storey costs £45k–£165k inc VAT, often no planning needed. Two storey costs 50–70% more but doubles your floor area. Full cost, planning, and value comparison for 2026.
Orangery vs Extension London: Which Is Right for You?
Orangery vs extension comparison. Orangeries £30k-£80k (more light, £500-1000/m² cheaper), extensions £50k-£120k (better insulation). Planning permission, costs, ROI.
Wrap-Around Extension London: Complete Guide to L-Shaped Extensions
Wrap-around extensions combine side return + rear extension for maximum space. £75k-145k cost, planning permission needed, ideal for terraced houses.
Extension vs New Kitchen: Which Adds More Value?
£50k kitchen vs £75k extension ROI analysis. Kitchen adds 5-10%, extension adds 10-15%. Combined strategies and decision framework.
Hidden Costs of London Extensions: What Builders Don't Tell You
The real costs builders don't quote. Party wall £1-3k, asbestos £2-8k, drainage £3-15k, CIL charges. Add 15-25% to builder quotes for realistic budgets.
Extension ROI London 2025: How Much Value Will You Add?
Will your extension pay for itself? Data-driven ROI analysis. Single storey adds 10-15%, loft conversions 15%, two storey 15-25%. When extensions make financial sense.
Extension Financing London 2025: Loans, Mortgages & Payment Options
How to finance your London extension. Remortgage vs loans, further advance, staged payments. Compare costs for £50k-150k projects.
Permitted Development Rights London 2026: Complete Guide
Everything you need to know about building without planning permission in London. Borough-specific rules, Article 4 directions, and instant permitted development checker.
London Extension Costs 2025: Real Project Data
Actual extension costs from 5,000+ London projects. Ground floor, loft, side return costs by borough with free calculator.
Loft Conversion London 2026: Costs, Types & Planning Guide
Loft conversion costs London 2026 inc VAT: Velux £50k–£65k, Dormer £60k–£80k, Mansard £80k–£120k. Planning rules, building regulations, party wall requirements and full timeline.
Rear Extension London 2026: Costs, Sizes & Planning Guide
Rear extension costs London 2026 inc VAT: 3m×5m £62k–£90k, 4m×5m £82k–£118k, 5m×6m £122k–£178k. Permitted development rules, prior approval scheme, design decisions and timeline.
Terraced House Extension London: Complete Guide
Extension options for London terraced houses. permitted development limits, party walls, side returns, wrap-around extensions, and cost breakdowns.
Conservation Area Extension London: Rules & Costs
Building in conservation areas. Restricted permitted development rights, planning requirements, materials, costs, and getting approval in 600+ London areas.
Building Regulations for Extensions 2026
Complete guide to building regs for extensions. Structural, fire safety, insulation, ventilation requirements. Costs and inspection stages.
Party Wall Agreement London: Complete Guide
Everything about Party Wall Act. When required, the process, costs (£700-1,500 per side), timeline, and handling neighbour disputes.
Two Storey Extension London: Costs & Planning
Two-storey extension guide. Costs £130k-150k, planning permission, design considerations, structural requirements, and timeline.
Semi-Detached House Extension London
Extension options for semi-detached houses. permitted development limits, rear and side extensions, loft conversions, costs, and one-side party walls.
Kitchen Extension London: Design & Costs
Kitchen extension guide. Open-plan layouts, bi-fold doors, lighting, costs £75k-120k. Rear, side return, and wrap-around options.
London Extension Timeline & Process 2025
Complete extension timeline from design to completion. 6-12 months typical. Planning, building regs, party wall, construction stages.
Architect vs Online Service: Which Is Best?
Honest comparison of traditional architects vs online services like Mayfair Studio. Costs, design quality, when to use each approach.
1930s Semi Extension London 2026: Guide
1930s semi extension London 2026: rear £55k–£120k, side £45k–£85k, hip-to-gable £55k–£90k, wrap-around £80k–£150k inc VAT. Planning and structure guide.
Victorian House Extension London 2026
Victorian house extension costs London 2026: side return £40k–£75k, rear £55k–£120k, wrap-around £80k–£150k, loft £55k–£120k. Conservation areas covered.
Detached House Extension London 2026
Detached house extension London 2026: rear £82k–£118k, two-storey £140k–£220k, wrap-around £110k–£170k inc VAT. 8m PD rules and design guide.
Dormer Extension London 2026: Costs & Rules
Dormer extension London 2026: flat roof, shed, hip-to-gable and L-shaped dormers. Costs, Class B permitted development rules, and party wall guidance.
Mansard Loft Conversion London 2026: Costs
Mansard loft conversion London 2026: basic £65k–£95k, mid-range £90k–£130k, high-spec £130k–£180k inc VAT. Planning, party wall, and space vs rear dormer.
Loft Conversion London 2025: Costs & Guide
London loft conversion guide 2025: dormer, mansard, hip-to-gable costs £45k–£85k. Building regulations, planning rules, and common mistakes to avoid.
Rear Extension London 2025: Cost & Planning
Rear extension London guide 2025: single-storey costs £75k–£120k, two-storey £110k–£150k. Permitted development limits, planning rules, and design options.
Flat Extension London 2026: Leasehold Guide
Flat extension London 2026: costs £55k–£130k inc VAT. No permitted development for flats - planning permission always required. Leasehold consent explained.
Upward Extensions London 2026: Add a Storey
Add a storey to your London home 2026: Class AA and AB permitted development, prior approval, costs £120k–£200k+ inc VAT, and structural challenges.
Extension Above a Garage London 2026
Extension above a garage London 2026: integral £25k–£45k, new storey above integral £55k–£90k, above detached £65k–£110k inc VAT. Planning and structure guide.
3m Kitchen Extension London 2026: Guide
3m kitchen extension London 2026: costs £50k–£108k inc VAT depending on width. No planning application under permitted development. Layouts and design tips.
Porch Extension London 2026: Costs & Guide
Complete guide to porch extensions in London. Costs from £2,000, permitted development rules, design options for Victorian and modern homes. Updated 2026.
Modular Extensions London 2026: SIPs Guide
Modular extensions London 2026: SIPs, timber frame, steel frame and volumetric pods. Costs vs traditional build, planning rules, building regs, and mortgages.
Granny Annexe London 2026: Costs & Rules
Granny annexe London 2026: planning rules, garage conversion £25k–£50k, extension annexe £60k–£120k inc VAT, CIL exemption, and council tax discount explained.
Garden Room vs Extension London 2026
Garden room vs extension London 2026: garden rooms £15k–£40k, extensions £50k–£120k+. Planning rules, value added, build time, and which option suits your plot.
Extension Cost by Size London 2026
London extension costs by size 2026: 3m×6m is £72k–£110k, 4m×6m is £98k–£142k, all inc VAT. Covers architect, engineer, building regs and contingency.
Kitchen Extension Cost London 2026: Prices
Kitchen extension costs London 2026: small 15m² from £60k, medium 20m² from £85k, large 30m² from £120k inc VAT. Build cost vs kitchen fit-out by spec level.
Extension Financing London 2026
Finance a London extension in 2026: remortgage, further advance, or home improvement loan compared. Options for £50k–£150k projects with staged payments.
Extension ROI London 2026: Value Added
Will your extension pay for itself? Complete ROI analysis for London extensions. Find out which projects add 15-25% value vs which lose money.
Home Extension Challenges London 2026
Builder shortages, rising material costs, planning delays and Part L changes - the key challenges facing London homeowners extending their properties in 2026.
Extend vs Move House London 2025
Should you extend or move house in London? Complete cost comparison including stamp duty 2025 changes, extension costs, moving costs, and ROI analysis.
Council Tax & Home Extensions London
Does a home extension raise council tax in London? Usually not while you live there - here is what triggers a VOA reassessment and how to respond if it does.
Home Extension Insurance London Guide
Home extension insurance London: notify your insurer, arrange site cover, and get a structural warranty. What each policy covers and when you need it.
Permitted Development Rights London 2025
Permitted development rights London 2025: size limits by type, Article 4 directions by borough, what you can build without planning permission. Oct 2025.
Permitted Development Changes 2026
PD changes 2026: larger rear extensions without planning permission, simplified loft conversion rules, curtilage changes. What London homeowners should do now.
Prior Approval London 2026: How to Apply
Complete guide to prior approval in London. Larger home extensions, office to residential conversions, and other developments that need council notification.
Building Regs for Extensions 2025: Guide
Building regulations for home extensions: structural, fire, insulation and drainage rules explained. Approval costs £1,000–£2,000 with full inspection stages.
Building Control London Extensions 2026
Building control for London extensions 2026: full plans vs building notice, inspection stages, completion certificates, LABC vs approved inspectors, and fees.
Listed Building Extension London 2025
Extending a listed building in London needs listed building consent. Grade I and II rules, conservation officer advice, and realistic costs explained.
Lawful Development Certificate London 2026
Lawful development certificate London: £206 application fee, £700–£2,000 all-in. When you need CLOPUD vs CLEUD and how to build a strong 8-week case.
4-Year Rule Dead: 10-Year Enforcement 2026
The 4-year rule is replaced by a 10-year enforcement period from April 2024. What this means for London homeowners, mortgages, and certificates of lawful use.
45-Degree Rule: London Extensions Guide
45-degree rule for London extensions: how it is measured, which boroughs apply it, and what to do if your design fails the test. 25-degree rule also covered.
Planning Refused: London Extensions Guide
Around 30% of householder planning applications in London are refused. Here are the 10 most common reasons - and how to avoid each one before you submit.
Future Homes Standard 2026 Extensions
Future Homes Standard and London extensions 2026: Part L U-values (walls 0.18, roof 0.15), heat pumps, triple glazing, MVHR, solar PV, and 0% VAT on upgrades.
Build Over Agreement London: Thames Water
Building within 3m of a public sewer? Thames Water build over approval takes 6–12 weeks and costs £300–£1,000. Step-by-step guide for London extension owners.
Right to Light London 2026: Rules & Costs
Right to light can stop your extension even with planning permission. 45-degree rule explained, BRE daylight assessment from £800, how to resolve neighbour disputes.
CDM Regulations: London Home Extensions
CDM Regulations 2015 for London home extensions: when they apply, domestic client duties, duty holders, HSE F10 notification, and the Health and Safety file.
Bifold vs Sliding Doors for Extensions 2026
Bifold doors £3k-8k vs sliding doors £4k-12k for extensions. Bifolds open 90%+, sliding offer slim sightlines and better thermals. Full London comparison guide.
Roof Lantern vs Skylight for Extensions
Skylights from £500 or roof lanterns from £2,500? Compare light performance, thermal efficiency, planning rules, and design impact for your London extension.
Kitchen-Diner Extension Layouts London
Six proven kitchen-diner extension layouts for London homes. Galley, L-shaped, island, linear, U-shaped, and broken-plan designs with costs and minimum sizes.
London Stock Brick Matching for Extensions
How to match London stock bricks for extensions. New vs reclaimed, mortar matching, conservation area requirements, and sourcing guide. Updated 2026.
Underfloor Heating Extensions London 2026
Underfloor heating for London extensions 2026: wet vs electric UFH from £25/m², Part L building regs compliance, best flooring choices, and installation advice.
Heat Pumps & Extensions London 2026
Heat pump during a London extension 2026: costs inc VAT, the £7,500 Boiler Upgrade Scheme grant, underfloor heating, running cost vs gas, and planning rules.
Solar Panels on Extensions London 2026
Solar panels on extensions London 2026: Part 14 Class A planning rules, costs from £1,400/kWp, SEG payments, battery storage, and typical payback periods.
Camden Extension Guide 2025: Costs & Rules
Camden extension guide 2025: planning rules, permitted development, Article 4 directions, conservation areas, basement policy, and costs. Updated Oct 2025.
Camden Extension Guide 2026: Costs & Rules
Camden extension guide 2026: planning rules, permitted development, Article 4 directions, conservation areas, basement policy, and costs. Updated Feb 2026.
Hackney Extension Guide 2025: Costs & Rules
Complete guide to home extensions in Hackney. New SPD guidance, planning permission, conservation areas, basement policy, and typical costs. Updated 2025.
Hackney Extension Guide 2026: Costs & Rules
Complete guide to home extensions in Hackney. New SPD guidance, planning permission, conservation areas, basement policy, and typical costs. Updated 2026.
Lambeth Extension Rules 2025: Costs & Guide
Complete guide to home extensions in Lambeth. Planning rules, basement SPD, conservation areas, design guidance, and typical costs. Updated 2025.
Lambeth Extension Rules 2026: Costs & Guide
Complete guide to home extensions in Lambeth. Planning rules, basement SPD, conservation areas, design guidance, and typical costs. Updated 2026.
Wandsworth Extension Planning 2025
Wandsworth extension guide 2025: permitted development rules, basement policy, conservation areas, and typical costs for rear and side return extensions.
Wandsworth Extension Planning 2026
Wandsworth extension guide 2026: permitted development rules, basement policy, conservation areas, and typical costs for rear and side return extensions.
Kensington & Chelsea Extension Guide 2026
Extending in Kensington & Chelsea (RBKC)? 73% conservation coverage, strict basement rules, costs 20–30% above London average. Expert planning and design guide.
Barnet Extension Guide 2026: Costs & Rules
Extending in Barnet in 2026? Covers permitted development, Hampstead Garden Suburb restrictions, conservation areas, Article 4 directions, and typical costs.
Brent Extension Guide 2026: Costs & Rules
Guide to home extensions in Brent 2026. Covers the new January 2025 SPD, conservation areas, Article 4 directions, Mapesbury Estate rules, and typical costs.
Ealing Home Extension Guide 2026
Extending in Ealing 2026: SPD 4 design rules, Brentham Garden Estate Article 4 direction, conservation areas, planning tips, and typical 2026 costs inc VAT.
Haringey Extensions 2026: Planning & Costs
Home extensions in Haringey 2026: planning rules, conservation areas in Crouch End, Muswell Hill and Highgate, Article 4 directions, and 2026 costs.
Lewisham Extensions 2026: Planning & Costs
Extending in Lewisham 2026: permitted development, Brockley and Blackheath conservation areas, Article 4 directions, planning tips, and 2026 costs inc VAT.
Merton Extensions 2026: Planning & Costs
Home extensions in Merton 2026: planning rules, Wimbledon and Mitcham conservation areas, Article 4 directions, and costs for SW19, SW20, CR4, SM4.
Richmond Extensions 2026: Planning & Costs
Home extensions in Richmond upon Thames 2026: conservation areas in Kew, Twickenham and Ham, Article 4 directions, Green Belt limits, and 2026 costs.
Architect Fees London 2026: What You'll Actually Pay
London architect fees 2026: 8–15% of build cost or £3k–£15k fixed. RIBA stage breakdown, what drives pricing, red flags to avoid, and how to compare quotes.