Which London Boroughs Approve the Most Extensions and Loft Conversions?

London councils approved 85.8% of householder planning applications decided between September 2025 and August 2026 (15,367 of 17,918 decisions in the 27 boroughs whose data passed our checks). Bexley (95.1%) and Southwark (95.0%) had the highest approval rates and Barking and Dagenham the lowest (69.2%). Two-storey extensions were refused most often (78.0% approved), and more than half of loft conversion decisions (52%) were lawful development certificates rather than planning applications.

Key findings

• 85.8% approved. 15,367 of 17,918 householder decisions, September 2025 to August 2026. The government's own figure for all London councils over July 2025 to June 2026 is also 85.8%.
• Most likely to approve: Bexley (95.1%), Southwark (95.0%), Merton (92.5%). Least likely: Barking and Dagenham (69.2%), Greenwich (77.5%), Hounslow (78.5%).
• Loft conversions: 82.0% of loft planning applications approved, and 90.6% of loft lawful development certificates granted. Highest loft approval: Southwark (94.6%), Bexley (90.5%), Wandsworth (90.2%). Lowest: Enfield (73.2%), Barnet (74.7%), Waltham Forest (76.0%).
• Extensions: 86.6% approved overall: wraparound 88.2%, rear 86.9%, side and infill 85.8%, two-storey 78.0%.
• Speed: the typical (median) decision took 8.0 weeks from validation, the statutory target. Fastest: Redbridge (6.7 weeks), Enfield (7.1 weeks). Slowest: Westminster (11.5 weeks), Merton (9.7 weeks).
• Fewer applications, more approvals: in the 23 boroughs with two comparable years, householder decisions fell 9.3% and the approval rate rose 2.0 points (83.6% to 85.6%). Official figures show the same direction (decisions -7.5%, approvals +2.1 points).
• Busiest: Wandsworth approved the most loft conversions (330) and Barnet the most extensions (777).

Approval rate by borough

Share of householder planning applications approved (approved ÷ approved + refused) in each of the 27 boroughs whose data passed our checks.

1. Bexley 95.1%
2. Southwark 95.0%
3. Merton 92.5%
4. Tower Hamlets 91.6%
5. Wandsworth 91.5%
6. Islington 91.0%
7. Sutton 90.8%
8. Haringey 90.3%
9. Hillingdon 89.9%
10. Lewisham 89.2%
11. Havering 89.0%
12. Camden 87.6%
13. Kingston upon Thames 86.6%
14. Ealing 86.4%
15. Croydon 85.1%
16. Newham 84.5%
17. Lambeth 83.4%
18. Redbridge 83.4%
19. Hackney 83.1%
20. Westminster 83.1%
21. Enfield 83.0%
22. Harrow 81.9%
23. Waltham Forest 79.9%
24. Barnet 79.2%
25. Hounslow 78.5%
26. Greenwich 77.5%
27. Barking and Dagenham 69.2%

Every borough compared

Select a column heading to sort. Loft and extension rates are shown where a borough decided at least 100 of them. "Official" is the government's householder approval rate for July 2025 to June 2026 (MHCLG), shown for every borough, including those whose Datahub feed was incomplete.

Download the data (CSV)

Loft conversions: half go the permitted development route

Many loft conversions do not need planning permission. The owner can instead ask the council for a lawful development certificate confirming the work is permitted development. In the 24 boroughs where both routes could be measured, 52% of loft decisions were certificates and 55% of loft approvals came that way. Loft certificates were granted 90.6% of the time, against 82.0% for loft conversions that needed a planning application, which tend to be the larger or more visible designs such as mansards and front dormers.

Highest loft approval rates (boroughs with at least 100 loft decisions): Southwark (94.6%), Bexley (90.5%), Wandsworth (90.2%). Lowest: Enfield (73.2%), Barnet (74.7%), Waltham Forest (76.0%). Our loft conversion cost guide covers what each type costs.

Extensions by type

Across the 27 boroughs, September 2025 to August 2026 (other routes where stated):

One application can describe several kinds of work (a rear extension and a loft, say), so the rows overlap. Two-storey extensions affect neighbours' light and outlook most, which is why councils refuse them more often. See our single vs double-storey guide, the house extension cost guide and our planning permission guide.

What this means if you are planning work

• Check first whether the work can be done under permitted development. If it can, a lawful development certificate confirms it, and loft certificates were granted 90.6% of the time. Our permitted development guide explains the limits.
• The borough matters: approval rates ran from 69.2% in Barking and Dagenham to 95.1% in Bexley. Read your council's design guidance before the drawings are finalised.
• Allow for the wait: the typical decision took 8.0 weeks after validation, and 11.5 weeks in Westminster.

How we did it

Sources. Every householder planning application, loft lawful development certificate and larger home extension prior approval with a decision dated 2025-09-01 to 2026-08-31, and the year before for comparison, from the Planning London Datahub, the Greater London Authority's live feed of planning applications from London's councils (81,914 records, queried 2026-10-03). Official figures come from the MHCLG live tables on planning application statistics (released 2026-09-24).

Measures. Approval rate = approved ÷ (approved + refused). Median weeks run from the date an application was validated to the decision date. Project types come from keyword rules applied to each application's description (for example "dormer", "mansard" or "hip to gable" for lofts).

Checks. Across London the Datahub held 85% of the householder decisions counted in the official statistics for July 2025 to June 2026, and its approval rate (85.8%) matches the official 85.8%. Boroughs with gaps in the feed are left out of the rankings and shown with their official figure only.

Limitations.

• The Datahub is an administrative feed from council systems and is not checked on receipt; some councils stop sending data for months. Boroughs with gaps are left out of the rankings (Brent, Bromley, City of London, Hammersmith and Fulham, Kensington and Chelsea, Richmond upon Thames).
• "Householder" means the application form the applicant chose; the official statistics use the council's own classification, so counts differ (by under 15% for 25 of the 27 boroughs we rank, 17% at most).
• Project types come from keyword rules applied to each application's description, and one application can count in several types. The rules were checked by hand on random samples (89 of 90 correct in the final check); applications the rules miss were not measured.
• Approval rate = approved ÷ (approved + refused). Withdrawn applications are excluded and appeal outcomes are not reflected.
• Median weeks run from validation to decision and include any extension of time agreed with the applicant.
• A lawful development certificate is not planning permission: it confirms the work is permitted development.
• Our 12 months (September 2025 to August 2026) differ from the official 12 months (July 2025 to June 2026) because several councils had not finished loading later decisions.
• The Datahub is live rather than versioned, so re-running the analysis later can give slightly different numbers.

Reuse. Our figures and the CSV are published under the Creative Commons Attribution 4.0 licence: please credit "Alstruct Ltd analysis of Planning London Datahub (GLA) and MHCLG data" and link to this page. MHCLG figures contain public sector information licensed under the Open Government Licence v3.0. Questions about the method: [email protected].

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