Open-plan kitchen extension in a 1930s Osterley TW7 house, architectural drawings for London Borough of Hounslow planning

Osterley · TW7 · Hounslow

Rear Extension Drawings in Osterley TW7

Fixed-fee, MCIAT-chartered rear extension drawings for Osterley (TW7) homeowners — London Borough of Hounslow validation and local constraints handled from the start.

Osterley is a green, spacious interwar suburb wrapped around Osterley Park, so the houses here are larger than the west-Hounslow average and the projects follow suit: wide rear extensions, two-storey side additions and generous loft conversions on the semis and detached homes along Jersey Road and Ellington Road. Bigger footprints mean many schemes go past permitted-development volume and land as full householder applications.

Because so much of the district sits within or beside the Osterley Park and Spring Grove conservation areas — and under mature, often protected street trees — we design to Hounslow Council's higher bar here, keeping the scale subordinate, matching brick and fenestration, and coordinating with an arboricultural approach where roots and TPOs affect the foundations.

Proposed floor plan

Osterley TW7

Osterley (TW7) — planning at a glance

Council: London Borough of Hounslow
Postcode district: TW7
Planning portal: View the Hounslow planning portal
Housing stock: Osterley is a leafy 1920s and 30s suburb of substantial semi-detached and detached houses on generous, tree-lined plots around Osterley Park. Roads like Jersey Road and Ellington Road carry larger family homes that suit full-width rear extensions, two-storey side additions and considered loft conversions.
Article 4: London Borough of Hounslow does not publish its Article 4 directions to the national planning register, so permitted development rights in Osterley (TW7) can’t be confirmed from open data alone — we check the direction schedule with the council before recommending a route, as part of the fixed fee. No published householder Article 4 in Osterley, but the Osterley Park and Spring Grove conservation areas set the tone — larger interwar houses in a leafy, parkland setting where scale, materials and mature-tree impact carry more weight than a formal direction.
Conservation: Osterley ParkSpring Grove
Sample streets: Ellington Road · Jersey Road · Alderney Avenue · Addison Avenue
Local constraints: The Osterley Park conservation area and National Trust parkland setting demand a sympathetic scale and materials palette on adjoining streetsThe Spring Grove conservation area protects the older villa character to the east of the districtMature street trees on the interwar avenues frequently carry Tree Preservation Orders that constrain foundation design near extensionsLarger detached and semi plots mean projects often exceed permitted development volume and need a full householder application

Planning in Osterley (TW7): what to know before you apply

No published householder Article 4 direction applies in Osterley, but the Osterley Park and Spring Grove conservation areas, the National Trust parkland setting and Tree Preservation Orders on mature street trees all tighten how extension scale, materials and foundations are assessed.

Typical Osterley housing stock

Osterley is a leafy 1920s and 30s suburb of substantial semi-detached and detached houses on generous, tree-lined plots around Osterley Park. Roads like Jersey Road and Ellington Road carry larger family homes that suit full-width rear extensions, two-storey side additions and considered loft conversions.

Streets we regularly draw for in Osterley

Ellington Road · Jersey Road · Alderney Avenue · Addison Avenue

Rear Extension Drawings for Osterley (TW7) homes: the package and the process

Every rear extension drawings we prepare for an Osterley property is drawn to London Borough of Hounslow’s validation standards and tuned to the TW7 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
Route	When it applies	Typical fee
Permitted development (Lawful Development Certificate)	Depth within 3m (terraced/semi) or 4m (detached), height and materials within PD limits	PD/LDC pack ~£950–£1,450
Larger home extension (prior approval)	Depth up to 6m (terraced/semi) or 8m (detached), with neighbour notification	from £1,100
Full householder planning permission	Extension exceeds PD/larger-home limits, or the property is in a conservation area with an Article 4 direction	Full Planning pack ~£1,600–£2,400
Planning + Building Regulations (structural)	Combined planning and construction-ready pack with structural calculations for the opening and roof	Planning + Building Regs pack ~£2,200–£3,850

Also in Osterley TW7

Planning Permission Planning Drawings Architectural Drawings Building Regulations Drawings Loft Conversion Drawings Rear Extension Drawings across Hounslow Rear Extension Drawings across London

FAQ

Rear Extension Drawings in Osterley TW7 — 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 an extension in Hounslow?+

It depends on the area. The interwar semis of Osterley, Hounslow and Feltham often retain permitted development rights for rear extensions and lofts, while the Chiswick terraces and Bedford Park sit within conservation areas where those rights are removed. We check your address against the designations first and can confirm permitted development with a Lawful Development Certificate.

What extra control applies in Bedford Park?+

Bedford Park is one of West London's most tightly controlled conservation areas, with detailed control over materials, rooflines, windows and front elevations. A standard permitted-development dormer or cladding change usually won't apply; instead we design to the area's Arts-and-Crafts character and prepare a full householder application with the elevations and materials the council expects.

Does Heathrow or the river affect my Hounslow project?+

They can. Toward the west of the borough, aircraft-noise considerations near Heathrow may influence habitable-room and glazing design, and along the Thames at Strand-on-the-Green and Isleworth the flood zone must be addressed. We evidence these considerations within the application where they apply so the council can validate and approve without repeated revisions.

How long does Hounslow Council take to decide?+

Hounslow determines most householder applications within the statutory eight-week period once validated; Bedford Park, conservation and riverside cases can involve additional consultation. We prepare submissions to the council's validation checklist to avoid the drawing queries that cause most delays.

How much do planning drawings cost in Hounslow?+

We agree a fixed fee before starting, typically around 30% below an architect's fee for the same council-accepted drawings, with free redraws until Hounslow approves. A suburban Osterley extension and a Bedford Park application differ in the evidence required, so we quote once we understand your address and project rather than by the hour.

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