House Extension Herne Hill SE24 Meets Three Appeals and a Refusal
Read a week of Lambeth’s planning list and a pattern emerges in SE24 that appears nowhere else in south London. On Railton Road an application for a rear dormer with three front rooflights was refused outright. On Chaucer Road, linked dormers across two houses went in retrospectively and are now at appeal. Further along Railton Road another scheme was settled only by an appeal decision. On Kestrel Avenue a dormer application arrived alongside a proposal to raise a party wall parapet.
Four roof cases in one borough list, producing one refusal, two appeals and a retrospective submission. This is not an area where you draw something and hope for the best, and it repays understanding why before commissioning anything at all.
Part of the answer is that Herne Hill is administratively awkward in a way few places are. It straddles the Lambeth and Southwark boundary around Brockwell Park. Three Lambeth conservation areas reach into it and a fourth, Southwark’s, covers the other side of one road. And every application here carries a constraint called the Herne Hill Neighbourhood Area, designated in December 2017, for which no community body has ever been permitted to write a plan. Design And Build covers SE24. Drawings, structural work, party wall notices and construction all come from people we employ ourselves.
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Your builders Herne Hill may answer to Southwark
Lambeth west, Southwark east, one street
The split here is not a vague thing about the edge of an area. It runs down the centre of a road, and Lambeth spells it out in its own conservation area profile.
The Herne Hill conservation area covers commercial and residential development around 1900 fronting the west side of Herne Hill near its junction with Half Moon Lane. Then the council adds that much of the development on the east side of Herne Hill Road falls within Southwark’s Stradella conservation area. Two authorities, two local plans, two validation checklists, two portals. A firm that knows one may know nothing about the other.
CA39, CA52 and CA61
Three Lambeth designations reach into SE24 and they were made decades apart, which tells you they were protecting different things.
Brockwell Park, CA39, came first on 10 December 1983 and was extended on 24 March 1999, covering the park itself and the properties along its southern and eastern edges. Poet’s Corner, CA52, followed on 12 October 1998. Herne Hill, CA61, came last in December 2007. A fourth, the Peabody Estate at Rosendale Road, covers CA53. Which one reaches a given address determines what an officer will look at first.
The former fire station and sorting office
Lambeth singles out two buildings in CA61 as being of particular note, and neither is a house. They are the former fire station and the former postal sorting office.
That matters more than it sounds. It tells you the character being protected around the station is a commercial and civic one of around 1900, complemented by buildings of similar age and materials. A residential scheme near that frontage is judged against public buildings rather than against the terrace it sits in, and the materials expected follow from that.
Poets Corner sets the terms for renovation and house extension Herne Hill
Four dormer cases, one refused and two at appeal
It is worth being precise about what happened, because the pattern is the argument. A Railton Road application for an L shaped rear dormer with three rooflights to the front elevation was refused.
On Chaucer Road, linked rear dormer extensions across numbers 68 and 70 were submitted retrospectively and have gone to the Planning Inspectorate. Another Railton Road scheme, adding space behind a retail unit and a floor above it to create a self contained maisonette, reached its final form only through an appeal decision. Roofs are where SE24 applications are decided, and a design that does not anticipate that is a design that will be tested.
Parapets, party walls and a linked dormer
The Kestrel Avenue application is instructive because of what it had to include: a rear dormer roof extension and the raising of a party wall parapet.
On a terrace, a dormer that meets the flank wall needs that wall taken up to meet it, and the wall is shared. So the work engages the Party Wall etc. Act 1996 as well as planning, and your neighbour has a statutory role whatever the council decides. Where two neighbours build linked dormers together, as on Chaucer Road, the party wall question becomes the easy part and the planning question becomes harder. Surveyors on our own staff serve the notices.
Retrospective, and what it costs you
More than one SE24 application in the record is marked retrospective, and it is worth being blunt about what that means in practice.
A retrospective application is not a formality and carries no presumption in your favour. The council assesses it exactly as it would have beforehand, except that the work already exists and the cost of removing it falls on you if the answer is no. It also surfaces at sale, when a buyer’s solicitor asks for the consent. Where a scheme genuinely needs no permission, a lawful development certificate settles the point in advance and costs a fraction of the argument.
Speculative housing that varies by year
Lambeth describes Poet’s Corner as a mid to late nineteenth century development of speculative housing for the middle classes, and adds the detail that matters for anyone renovating: the house styles and detailing vary depending on the date of construction.
So the street was built in tranches, by different hands, over a period. Brickwork, stucco and detailing shift as you walk along it, drawing on whichever historical style was in favour that year. Matching a repair to the house next door is not the same as matching it to your own. Interior design joins once those fabric decisions are settled.
Design and build Herne Hill: nothing changes hands mid-project
Designated in 2017, and refused the same day
This is the oddest thing about planning in Herne Hill, and it is stated plainly on Lambeth’s own neighbourhood planning page.
On 11 December 2017 the Cabinet approved the designation of the Herne Hill Neighbourhood Area in Lambeth. In the same decision, the application for the Herne Hill Neighbourhood Forum, made by the Herne Hill Forum, was refused. The area was created; the body that asked for it was not. Two years later the council recorded that there had been no subsequent application.
What a constraint means when nobody can write the plan
The practical effect shows up on every SE24 application. Herne Hill Neighbourhood Area In Lambeth appears in the constraints list alongside conservation areas and flood zones, on schemes as small as a garden room.
What it does not do is generate policy, because a neighbourhood plan needs a designated forum to write it and there is not one. Compare Kennington, where a made neighbourhood plan is cited in applications, or Norwood and Tulse Hill, which both have forums. Herne Hill has the boundary and none of the machinery. Anyone telling you a neighbourhood policy applies to your extension here is mistaken.
A draft appraisal still waiting after five years
There is a second document in limbo. Lambeth consulted on a draft character appraisal for Brockwell Park between 30 November 2020 and 11 January 2021, proposing to extend the conservation area boundary.
The proposals were substantial: stretches of Dulwich Road and Railton Road near the station, Herne Hill railway station itself, the viaduct, and the Lambeth half of the railway bridge. When last checked the document was still marked draft. A proposed boundary is not a boundary, and designing on the assumption that an extension has happened is designing against a rule that does not yet exist. We check the adopted position on the day.
Before a construction company Herne Hill quotes, check the ground
The Effra, culverted and still there
The River Effra runs beneath this part of south London in a culvert. It has not gone anywhere; it has simply been put in a pipe and built over.
Water still finds the low ground, and the parts of Herne Hill nearest the old course carry surface water considerations that the higher streets do not. It affects drainage strategy, where a soakaway can go, and occasionally whether an application needs a flood risk assessment. Put your own address into the national flood risk map. It takes a moment, and on a plot sitting this close to a buried watercourse the moment is well spent.
An island of undesignated ground on Dulwich Road
Lambeth’s own consultation contains a phrase worth knowing. Numbers 70 to 74 Dulwich Road, it records, are currently an island of undesignated conservation area between the Brockwell Park and Brixton Water Road designations.
Three houses, surrounded by protection, with none of their own. That is what conservation area boundaries actually look like on the ground here, and it is why we check the mapped line for a specific address rather than assuming that a street is in or out. The neighbours either side of that island are working to different rules from the middle.
Building at the back of an existing plot
Backland development is live in SE24 and it is more ambitious than most people expect. One Railton Road application proposes a part two, part three storey house on land to the rear, following demolition of what stands there now.
A garden room is the modest version of the same idea, and one on Gubyon Avenue was permitted. Between the two sits a wide range of what a back garden will take, and the answer turns on access, overlooking, the trees and the drainage rather than on floor area. Our structural engineers and architects look at the plot as a whole before anyone commits to a footprint.
Two documents, and we can tell you where you stand
The address and a photograph of the roof answer most of it. The address settles which council decides, which of the four conservation areas reaches you, and how close the old watercourse runs. The roof tells us what has already been done to it.
Send both and back comes the position: the determining authority, the designations in play, whether permitted development survives at your address, and what the record suggests about how a roof alteration will be received. We work throughout SE24 — Railton Road, Chaucer Road, Kestrel Avenue, Gubyon Avenue, Shakespeare Road, Milkwood Road, Half Moon Lane, Dulwich Road and the Poet’s Corner streets — submitting to Lambeth or Southwark as the address requires, and across East Dulwich, Dulwich, Gipsy Hill, Norwood, Kennington, Lambeth and the wider SE districts. Everything is delivered by one construction company on one agreement.
The survey is free. Here it starts by working out which council you are persuading.
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