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Free 2026 London Planning Report — Rear Extension Drawings in Herne Hill SE24

Single-storey rear extension behind an Edwardian terrace in Herne Hill SE24, London Borough of Lambeth
Herne Hill · SE24 · Lambeth

Rear Extension Drawings in Herne Hill SE24

Fixed-fee, MCIAT-chartered rear extension drawings for Herne Hill (SE24) homeowners — London Borough of Lambeth validation and local constraints handled from the start.

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Herne Hill (SE24) straddles the Lambeth–Southwark boundary around Brockwell Park, with its Lambeth side made up of desirable late-Victorian and Edwardian streets — including the Poets' Corner terraces off Railton Road. Rear and loft projects are the staple here, shaped by the conservation areas that cover much of the neighbourhood. (The Stradella Road conservation area lies just across the boundary in Southwark, so properties there answer to a different council.)

Lambeth's Brockwell Park and Herne Hill conservation areas closely control frontages and rooflines around the park and the Poets' Corner streets, and the low ground near the culverted River Effra brings flood-risk considerations. We check where a Herne Hill property sits relative to those designations — and which side of the borough boundary it falls — before recommending a permitted-development or full-application route.

Single-storey rear extension behind an Edwardian terrace in Herne Hill SE24, London Borough of Lambeth
Isometric illustration of a Herne Hill SE24 home rear extension drawings design
Proposed floor plan
Herne Hill SE24

Planning in Herne Hill (SE24): what to know before you apply

SE24 has no householder Article 4 direction, so many Herne Hill houses retain permitted development rights for rear and loft work — but Lambeth's Brockwell Park and Herne Hill conservation areas are the exceptions, controlling frontages and rooflines around the park and the Poets' Corner streets, and low-lying parts near the old River Effra carry flood-risk considerations. SE24 straddles the Lambeth–Southwark boundary, so we confirm which council a property falls under before advising.

Typical Herne Hill housing stock

Late-Victorian and Edwardian terraces and semi-detached houses on the streets around Brockwell Park, including the well-known Poets' Corner streets off Railton Road, with mansion flats along the main roads.

Streets we regularly draw for in Herne Hill

Half Moon Lane · Norwood Road · Shakespeare Road · Railton Road

What SE24 is actually built of

Measured from 264 classified residential buildings in SE24, not from a description of the area.

Herne Hill SE24 housing mix

Residential building form across the SE24 postcode district, from 264 classified buildings.

Attached on more than one side56%
Attached on one side35%
Detached8%
Median building footprint74 m²
Addresses per buildingAbove about 2 means flats and maisonettes dominate1.58
Buildings classified264

Source: Ordnance Survey National Geographic Database (derived statistics). Contains OS data © Crown copyright and database right 2026. Contains Royal Mail data © Royal Mail copyright and database right 2026. Extracted 2026-08-17.

Rear Extension Drawings for Herne Hill (SE24) homes: the package and the process

Depth is the number the application turns on, and it has to be measured from the original rear wall of the house rather than from whatever is there now. The drawings carry that dimension, the eaves and ridge heights, the position of any rooflight, and the boundary distances on both sides.

Where the scheme goes beyond the standard allowance and relies on the larger home extension route, the drawings serve a second purpose: they are what the council sends to the neighbours during the consultation. A clear, dimensioned proposed elevation answers the objection about overshadowing before it is made.

Depth is limited by the plot as much as by the rules. A long garden behind a terrace can take the full allowance, while a short one runs out before the rules do — and on a semi or detached house the same depth reads very differently from the boundary.

Do I need planning permission for a rear extension in London?

Many single-storey rear extensions qualify as permitted development, meaning no planning application is needed, provided depth, height and materials stay within set limits. That changes if your property sits in a conservation area or is subject to an Article 4 direction, both of which can remove permitted development rights across a street or borough — in that case a full householder planning application is required regardless of size.

Even where an extension qualifies, most homeowners obtain a Lawful Development Certificate to confirm that status in writing before building — useful for mortgage lenders, buyers and Building Control. We check your property against your borough's constraints before recommending a route.

How deep can a single-storey rear extension go?

Depth is the main constraint on a rear extension, and it depends on your house type and whether you use standard permitted development or the larger home extension scheme.

Permitted development

Standard permitted development allows a single-storey rear extension up to 3 metres deep for terraced and semi-detached houses, or 4 metres for detached houses, generally with eaves height limited to match or stay close to the existing house.

Larger home extension scheme

The prior-approval scheme extends this to 6 metres for terraced and semi-detached houses and 8 metres for detached houses. Your council writes to affected neighbours; if none object within the notification period, approval follows without a full planning application. If an objection is raised, the council assesses the impact on neighbouring light and outlook itself, rather than automatically refusing, so a well-considered design still has a good chance of approval.

Designing the kitchen-diner: rooflights, bi-folds and daylight

Most rear extensions exist to create one open-plan kitchen, dining and living space, so the drawing work focuses on getting light and flow right within the depth you are allowed.

  • Structural opening sized for bi-fold or sliding doors across most of the rear elevation
  • Rooflights or a roof lantern positioned to light the centre of the room, away from the shadow line of the main house
  • Open-plan layout tested against the 45-degree rule, which protects daylight to your neighbours' windows and can limit how close a flank wall or roof comes to the boundary
  • Floor build-up and threshold detail coordinated so the new floor meets the existing one without a step
Rear extension routes at a glance
RouteWhen it appliesTypical fee
Permitted development (Lawful Development Certificate)Depth within 3m (terraced/semi) or 4m (detached), height and materials within PD limitsPD/LDC pack ~£950–£1,450
Larger home extension (prior approval)Depth up to 6m (terraced/semi) or 8m (detached), with neighbour notificationfrom £1,100
Full householder planning permissionExtension exceeds PD/larger-home limits, or the property is in a conservation area with an Article 4 directionFull Planning pack ~£1,600–£2,400
Planning + Building Regulations (structural)Combined planning and construction-ready pack with structural calculations for the opening and roofPlanning + Building Regs pack ~£2,200–£3,850
Sheet from a rear extension drawings package drawn for a Herne Hill property in SE24, showing the existing and proposed arrangement at scale
A sheet from the rear extension drawings package we submit to London Borough of Lambeth for Herne Hill (SE24) properties.

Also in Herne Hill SE24

Planning PermissionPlanning DrawingsArchitectural DrawingsBuilding Regulations DrawingsLoft Conversion DrawingsRear Extension Drawings across LambethRear Extension Drawings across London
FAQ

Rear Extension Drawings in Herne Hill SE24 — FAQs

How much does a rear extension cost to design in London?+
Rear extension drawings start from £1,100, with the final fee set by the route your extension takes — permitted development, prior approval or full planning — and whether you need building regulations and structural calculations bundled in. The fee is fixed and agreed upfront.
Do I need an architect for a rear extension?+
No. DrawingsDirect is an MCIAT-chartered architectural technologist practice, producing the same council-accepted drawings as an architect for a fixed fee typically around 30% lower.
How long does it take to get rear extension drawings?+
Drawings are typically ready around 7 days from survey. Once submitted, councils have a statutory 8-week period to determine a standard householder planning application.
What is the 45-degree rule?+
It is a daylight test many London councils apply to check that a rear extension does not block too much light to a neighbour's nearest window, measured as a line drawn at 45 degrees from that window. We check it before submission, not after a refusal.
Will I need a Party Wall Agreement for a rear extension?+
Only if your foundations or new walls sit on or near the boundary with a neighbouring property. A straightforward rear extension set within your own plot often does not trigger the Party Wall etc. Act 1996, unlike a Side Return or Wraparound extension, which usually does.
Do I need planning permission for a side-return extension in Lambeth?+
On many of Lambeth's Victorian and Edwardian terraces in Brixton, Clapham and Streatham, a single-storey side-return or rear extension can fall within permitted development, so a full application isn't always required. Conservation areas such as Clapham Common and Brixton Water Lane can restrict this. We check your street's designation first and can confirm permitted development with a Lawful Development Certificate.
My Lambeth home is a converted flat — does that change things?+
It often does. Many Lambeth houses are converted flats, so ownership, lease and party-wall considerations can matter as much as the planning route, and the freeholder's agreement is usually needed alongside planning. We resolve the ownership and shared-structure context before drawing so the scheme is deliverable, not just consentable.
What does Lambeth's HMO Article 4 direction affect?+
Lambeth applies an Article 4 direction removing permitted development rights for HMO conversions (C3 to C4) in designated parts of the borough, so a change of use to a house in multiple occupation needs a full application there. It doesn't affect a standard family extension, but we confirm whether it applies to your address and use before advising on a route.
How long does Lambeth Council take to decide?+
Lambeth determines most householder applications within the statutory eight-week period once validated. The terraced grids around Clapham and Brixton are party-wall-sensitive with well-established design expectations, so the commonest delay is a drawing query — we prepare submissions to the borough's residential extension guidance to keep them moving.
How much do planning drawings cost in Lambeth?+
We agree a fixed fee before starting, usually around 30% below an architect's fee for the same council-accepted drawings, with free redraws until Lambeth approves. A side-return, a loft and a flat-conversion scheme differ in complexity, so we quote once we understand your street and project rather than charging by the hour.
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