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Free 2026 London Planning Report — Rear Extension Drawings in Harlesden NW10

Victorian terrace flat conversion near Harlesden High Street NW10 in the London Borough of Brent
Harlesden · NW10 · Brent

Rear Extension Drawings in Harlesden NW10

Fixed-fee, MCIAT-chartered rear extension drawings for Harlesden (NW10) homeowners — London Borough of Brent validation and local constraints handled from the start.

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Harlesden (NW10) is a dense Victorian terraced neighbourhood built around the High Street and the landmark Jubilee Clock, with a high share of houses already converted to flats. That mix means the work here spans rear and side-return extensions, loft conversions and the drawings that go with flat-conversion and change-of-use schemes.

The Harlesden conservation area covers the historic core around the High Street, so frontage changes, dormers and materials there face tighter control than on the surrounding streets. We check where a Harlesden property sits relative to that boundary, and whether it is in single-family or flatted use, before recommending a route and preparing the application to Brent's standards.

Victorian terrace flat conversion near Harlesden High Street NW10 in the London Borough of Brent
Isometric illustration of a Harlesden NW10 home rear extension drawings design
Proposed floor plan
Harlesden NW10

Planning in Harlesden (NW10): what to know before you apply

NW10 has no published householder Article 4 direction in Harlesden affecting typical extensions, so many terraces retain permitted development rights — but the Harlesden conservation area around the High Street is the exception, and the high level of existing flat conversions means amenity and layout are scrutinised closely.

Typical Harlesden housing stock

Dense Victorian terraces radiating from the High Street and the Jubilee Clock, a large share already converted to flats, alongside pockets of later infill — a mix that makes both extensions and conversion-related work common.

Streets we regularly draw for in Harlesden

Tubbs Road · Craven Road · Winchelsea Road · Crownhill Road

Rear Extension Drawings for Harlesden (NW10) homes: the package and the process

Every rear extension drawings we prepare for an Harlesden property is drawn to London Borough of Brent’s validation standards and tuned to the NW10 constraints above. Here is what the drawing package covers and how the process runs from first survey to approval.

A single-storey rear extension is the most common way London homeowners add space, usually taking the form of an open-plan kitchen-diner that opens onto the garden through bi-fold or sliding doors, with rooflights or a roof lantern bringing daylight deep into the plan. Because depth and height are tightly controlled by permitted development rules and by the 45-degree rule that protects neighbouring windows, the design work sits as much in checking what the council will allow as in drawing what you want.

DrawingsDirect draws rear extensions for permitted development, the larger home extension prior-approval scheme and full householder planning, with structural calculations for the opening and roof produced in-house by our MCIAT-chartered team. If your project also involves widening the kitchen sideways or adding a second storey, see our Side Return, Wraparound and Double Storey Extension pages — many London rear extensions grow into one of those during design.

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.

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

Also in Harlesden NW10

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

Rear Extension Drawings in Harlesden NW10 — 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 Brent?+
On the Victorian and Edwardian terraces of Kilburn, Willesden and Harlesden a single-storey side-return or rear extension can fall within permitted development, so a full application isn't always needed. Conservation areas such as Queen's Park and Mapesbury restrict this. We check your street's designation first and can confirm permitted development with a Lawful Development Certificate where it qualifies.
What does Brent's borough-wide HMO Article 4 direction affect?+
Brent applies a borough-wide Article 4 direction removing permitted development rights for change of use to an HMO (C3 to C4), so a conversion to a house in multiple occupation needs a full application anywhere in the borough. It doesn't affect a standard family extension or loft, but we confirm whether it applies to your intended use before advising.
Is a hip-to-gable loft conversion allowed on my Brent semi?+
Frequently, yes. The interwar semis of Wembley, Kingsbury and Sudbury suit hip-to-gable and dormer conversions, which often qualify as permitted development within the volume limits. We confirm eligibility against those limits and any conservation or Article 4 constraint, then produce the planning and building-regulations drawings.
How long does Brent Council take to decide?+
Brent determines most householder applications within the statutory eight-week period once validated; conservation cases can attract additional consultation. The dense terraced streets are party-wall-sensitive, so the commonest delay is a drawing query — we prepare submissions to the council's householder guidance to keep them moving.
How much do planning drawings cost in Brent?+
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 Brent approves. A side-return, a hip-to-gable loft and a conservation-area application differ in complexity, so we quote once we understand your street and project rather than by the hour.
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