The Hardest London Boroughs for a House Extension

Two things make a householder application expensive: being refused, and waiting. This index adds a borough's refusal rate to the share of its decisions that ran past thirteen weeks, over 2023 Q2 to 2026 Q1, and ranks all 32 boroughs with both figures published. It sits alongside our borough approval-rate league table, which covers a different and more recent window.

The short version

Hardest: Westminster — score 33.0 (16.8% refused, 16.2% over thirteen weeks).
Easiest: Southwark — score 7.4 (6.2% refused, 1.2% over thirteen weeks).
The formula is refusal rate + over-13-week share, equal weight, both in percentage points. Both inputs are in the table.
Boroughs below the 30-decision publication floor are listed but not scored.
This is our index built on official figures, not an official ranking.

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Every borough scored, hardest first

Higher is harder. A borough can reach the same score two different ways — a strict authority that decides quickly and a permissive one with a long tail can land within a point of each other — so read the two input columns, not just the total.

London boroughs scored on householder planning difficulty, 2023 Q2 to 2026 Q1
#	Borough	Difficulty	Refused	Over 13 weeks	Decisions
1	Westminster	33.0	16.8%	16.2%	1,294
2	Hounslow	32.8	30.1%	2.7%	2,310
3	Greenwich	31.8	29.3%	2.5%	2,301
4	Barking and Dagenham	30.3	30.3%	0.0%	1,239
5	Camden	28.5	11.3%	17.2%	1,179
6	Waltham Forest	27.4	22.9%	4.5%	2,281
7	Harrow	27.1	22.2%	4.9%	2,856
8	Hackney	26.3	18.7%	7.6%	1,350
9	Bromley	25.3	20.2%	5.1%	4,706
10	Enfield	24.8	22.2%	2.6%	2,814
11	Kingston upon Thames	23.3	21.6%	1.7%	2,454
12	Brent	22.3	21.5%	0.8%	2,843
13	Richmond upon Thames	21.3	19.8%	1.5%	4,125
14	Croydon	21.2	18.4%	2.8%	2,701
15	Lambeth	20.2	19.9%	0.3%	1,736
16	Barnet	19.5	16.5%	3.0%	4,584
17	Havering	18.8	18.2%	0.6%	3,218
18	Redbridge	18.6	18.2%	0.4%	3,246
19	Hillingdon	18.3	15.8%	2.5%	3,978
20	Haringey	17.8	10.5%	7.3%	2,227
21	Lewisham	15.7	13.7%	2.0%	2,037
22	Tower Hamlets	15.7	13.0%	2.7%	563
23	Wandsworth	14.6	8.7%	5.9%	3,107
24	Newham	14.2	14.2%	0.0%	1,313
25	Sutton	14.1	13.7%	0.4%	2,141
26	Ealing	13.8	13.4%	0.4%	3,182
27	Islington	12.2	9.1%	3.1%	1,279
28	Kensington and Chelsea	11.7	9.8%	1.9%	2,072
29	Merton	11.4	11.1%	0.3%	2,494
30	Hammersmith and Fulham	10.2	4.0%	6.2%	1,569
31	Bexley	9.2	8.3%	0.9%	2,859
32	Southwark	7.4	6.2%	1.2%	1,617
—	the City of London	not scored	—	—	5

Source: MHCLG District Planning Application Statistics (PS1 and PS2), covering 2023 Q2 to 2026 Q1 — published quarterly by the Ministry of Housing, Communities and Local Government. Figures count decisions made in that window, not applications submitted, so a borough with a long queue reports the decisions it reached rather than the backlog behind them. Boroughs below 30 decisions are shown as not published and are excluded from every ranking on this page. Contains public sector information licensed under the Open Government Licence v3.0.

How the score is built, and what it deliberately ignores

Refusal rate comes from PS2: approvals and refusals of householder applications decided in the window. The delay term is the share of those decisions recorded as taking more than thirteen weeks. Both are percentage points, both point the same way — higher is worse — so they are simply added. No normalisation, no weighting that a reader cannot see and disagree with.

What the index ignores is as important as what it includes. It does not know about conservation areas, Article 4 directions, tree preservation orders, or the difference between a modest rear extension and a full-width two-storey wraparound. It cannot see applications withdrawn before decision, which is how a difficult borough quietly keeps its refusal rate down. And it says nothing about appeals, where a refused scheme can still succeed. Treat it as a map of where the friction sits across London, not as a forecast for one address.

Two things sit outside the index entirely and change the arithmetic for a given project. Work that falls under permitted development never reaches these figures at all, because it needs no planning application — and a lawful development certificate is the way to prove that in writing without asking permission. And the eight-week clock starts at validation, not at submission, so a package the council rejects at the door spends time that no borough's published figures ever record. If the question behind reading this table is what the work will cost rather than whether it will pass, the extension cost calculator and our published fees answer that one directly.

Questions people ask about difficult boroughs

What is the hardest London borough to get an extension approved in?

On this index, Westminster — it refuses 16.8% of householder applications and lets 16.2% of decisions run past thirteen weeks, for a combined difficulty score of 33.0. The index is refusal rate plus the over-thirteen-week share, equally weighted; both inputs are in the table.

And the easiest?

Southwark, scoring 7.4 — a 6.2% refusal rate and 1.2% of decisions past thirteen weeks. That is roughly 4.5 times easier than the top of the table on this measure.

Why combine refusal rate and delay into one score?

Because they are the two ways a householder application costs money. A refusal costs a redesign and a resubmission; a decision that runs months past target costs a held builder slot and a delayed start. A borough that is generous but slow and a borough that is quick but strict present different problems, and this index says so rather than pretending one dimension is the whole story.

Should I avoid buying in a difficult borough?

No. The index describes a council's caseload, not a specific property. A well-precedented rear extension in a high-scoring borough is a far safer proposition than an ambitious scheme in a low-scoring one, and none of these figures know anything about a particular street, conservation area, or Article 4 direction.

Is this an official government ranking?

No. The underlying decisions and timings are official MHCLG statistics; the combination into a single score is ours, and the formula is published above so it can be checked or recomputed with different weights.