Prior approval for a larger rear extension in Merton: why most go straight through
In the eight quarters to June 2026, Merton answered 284 larger home extension notifications with prior approval not required: a go-ahead with no decision to make. Where it did decide, it granted 36 and refused 153. If your house sits outside a conservation area, the odds of a clean pass are reasonable, and the drawings are what keep them that way. We measure, draw and submit for a fixed £595.
Fixed fee from £395 drawings + £200 survey (£595 total) · all prices
Prefer to talk it through?
Merton's record, in three numbers
MHCLG publishes each council's prior approval figures every quarter. Adding up the eight quarters from 2024 Q3 to 2026 Q2, Merton recorded 284 larger home extension notifications where prior approval was not required, 36 granted and 153 refused. That is 473 in all, our own sum of the three counts.
The shape is the useful part. Roughly six in ten, about 60% on our calculation, ended in a go-ahead with nothing to decide. The remaining 189 needed a decision, and 153 of those were refused, about 81%. So the typical Merton notification passes cleanly, and the ones that do not tend to fail firmly. The aim is to be in the first group.
Prior Approval Extension Drawings in Merton
from £595
£395 drawings + £200 survey (£595 total)
Every price is the full fixed fee you pay. No VAT is charged. Council application fees are paid to the council separately.
What you get
- A measured survey visit to the house and garden
- Plans and rear elevation showing depth and height at each boundary
- The written description: depth, maximum height and eaves height
- The list of adjoining addresses Merton must notify
- Submission to the council as your agent, with replies to its questions
- A constraint check for conservation areas and Article 4 on your address
- Survey and constraint check
We measure the house and read the council's conservation area map against your address.
- Draw the notification
Plans, rear elevation, written description and adjoining addresses, to scale.
- Council notifies neighbours
Adjoining owners and occupiers have at least 21 days to comment.
- Not required, or a decision
Most Merton notifications end with no decision needed. Some need one.
- Decision by day 42
If 42 days pass without a written decision, the order lets work start.
Why a clean notification goes through
Prior approval not required means the council read the notification, saw nothing among the neighbours' responses that called for a judgement, and left it. The council can weigh only the effect on adjoining homes, never the design or the materials, so a set that shows the depth and the wall height beside each neighbour leaves little to dispute.
That is why we draw the rear elevation with the boundary in view and give the written description the exact depth, the maximum height and the eaves height. We cannot promise what the council or your neighbours will say. We can make sure the facts on the page match what we measured.
Merton has 28 live conservation area entries on the government's planning data register at our extraction on 19 October 2026.
Detached houses and the 8 metre depth
Under Class A.1(g) of the General Permitted Development Order a single-storey rear extension can go 6 metres beyond the original rear wall of a terraced or semi-detached house, and 8 metres on a detached one, no higher than 4 metres. If your house is detached, the extra 2 metres are available to it and to no other type of house.
More depth means more reach into a neighbour's outlook, so the longer the extension, the more the boundary drawing matters. If you have extended before, the earlier extension counts against the original rear wall, and we take that from the survey. Our guide to the larger home extension scheme covers the rules in more depth.
The conservation area check
The 6 metre and 8 metre depths do not apply in a conservation area. Merton has 28 live conservation area entries on the government's planning data register at our extraction on 19 October 2026. Our data has no Article 4 row for Merton, which does not rule one out for a particular street, so we check the council's map for your address on the survey day.
If the house is in a conservation area, the scheme is closed to it. We then use the same survey for a householder planning application, and say so before you buy anything further.
Fee, timing and what comes next
Our fee is a fixed £595 with the survey included and no VAT charged. The council's own fee of £249 is separate. Neighbours have at least 21 days to comment and the council has 42 days from a complete notification to decide.
Prior approval covers planning only. Building regulations drawings and, near a shared wall, party wall notices come after, and we can carry the same survey into both.
Sources
Every figure on this page, where it comes from and a link to the original.
| Figure | Source | Link |
|---|---|---|
| 6 metres | GPDO 2015 Sch 2 Pt 1 Class A.1(g): larger single-storey rear extension, maximum depth beyond the rear wall for a house other than detached, subject to prior approval under A.4 (source wording: "6 metres") | www.legislation.gov.uk |
| 8 metres | GPDO 2015 Sch 2 Pt 1 Class A.1(g): larger single-storey rear extension, maximum depth beyond the rear wall for a detached house (source wording: "8 metres") | www.legislation.gov.uk |
| 4 metres | GPDO 2015 Sch 2 Pt 1 Class A.1(f)-(g): a single-storey rear extension may not exceed 4 metres in height (source wording: "exceed 4 metres in height") | www.legislation.gov.uk |
| 42 days | GPDO 2015 Sch 2 Pt 1 Class A.4(10)(c): work may start if the council has not notified a decision within 42 days of receiving the information (source wording: "the expiry of 42 days") | www.legislation.gov.uk |
| £249 | Statutory fee from 1 April 2026: prior approval for a householder larger rear extension (GPDO Part 1 Class A) | assets.publishing.service.gov.uk |
| 284 | Our analysis of MHCLG planning application statistics, table PS1 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 36 | Our analysis of MHCLG planning application statistics, table PS1 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 153 | Our analysis of MHCLG planning application statistics, table PS1 (district open data table) (released 24 Sep 2026, quarters to 2026 Q2) | www.gov.uk |
| 28 | Our analysis of the MHCLG Planning Data Platform conservation-area register (extracted 19 Oct 2026) | www.planning.data.gov.uk |
Questions people ask
How many Merton notifications need no decision?
If prior approval is not required, can I start building?
Is Merton refusing most decisions?
Is my Merton house in a conservation area?
Photographs: David Anstiss (CC BY-SA 2.0).
