Hip-to-gable loft conversion on a 1930s Cranford TW5 semi, permitted development drawings for London Borough of Hounslow

Cranford · TW5 · Hounslow

Rear Extension Drawings in Cranford TW5

Fixed-fee, MCIAT-chartered rear extension drawings for Cranford (TW5) homeowners — London Borough of Hounslow validation and local constraints handled from the start.

Cranford sits on the western edge of Hounslow near the Heathrow boundary, and its interwar and post-war housing makes it a straightforward, permitted-development-friendly area for family projects: rear extensions, side infills and loft conversions on the semis along The Avenue, Berkeley Avenue and Chaucer Avenue, where back gardens give plenty of room to extend.

Away from the Cranford Village and Cranford Park conservation areas most schemes proceed under permitted development, but we design to Hounslow Council's standard throughout — factoring in aircraft-noise glazing and ventilation near Heathrow, party wall coordination on semi-detached plots, and flood-aware drainage on the lower ground close to the River Crane.

Proposed floor plan

Cranford TW5

Cranford (TW5) — planning at a glance

Council: London Borough of Hounslow
Postcode district: TW5
Planning portal: View the Hounslow planning portal
Housing stock: Cranford is a suburban district on the Heathrow fringe, made up of 1930s semis and post-war housing on roads like The Avenue and Berkeley Avenue, with generous back gardens. The stock suits single-storey rear extensions, side infills and hip-to-gable loft conversions carried out under permitted development.
Article 4: London Borough of Hounslow does not publish its Article 4 directions to the national planning register, so permitted development rights in Cranford (TW5) 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 Cranford — this Heathrow-fringe suburb of interwar and post-war housing is largely permitted-development friendly, with the Cranford Park and Cranford Village conservation areas the main localised constraint rather than a blanket direction.
Conservation: Cranford ParkCranford Village
Sample streets: The Avenue · Berkeley Avenue · Chaucer Avenue · Cranford Lane
Local constraints: The Cranford Village and Cranford Park conservation areas protect the historic core and parkland edge, tightening design near those pocketsProximity to Heathrow places much of the area under aircraft-noise designations that affect glazing and ventilation specificationThe predominantly semi-detached stock means party wall agreements are routine for rear and side extensionsLand near the River Crane and Cranford Park can fall within flood zones requiring drainage-conscious design

Planning in Cranford (TW5): what to know before you apply

No published householder Article 4 direction applies in Cranford, so most extensions and lofts fall under permitted development. The Cranford Village and Cranford Park conservation areas, Heathrow aircraft-noise designations and localised flood risk near the River Crane are the constraints to design around.

Typical Cranford housing stock

Cranford is a suburban district on the Heathrow fringe, made up of 1930s semis and post-war housing on roads like The Avenue and Berkeley Avenue, with generous back gardens. The stock suits single-storey rear extensions, side infills and hip-to-gable loft conversions carried out under permitted development.

Streets we regularly draw for in Cranford

The Avenue · Berkeley Avenue · Chaucer Avenue · Cranford Lane

What TW5 is actually built of

Measured from 265 classified residential buildings in TW5, not from a description of the area.

Cranford TW5 housing mix

Residential building form across the TW5 postcode district, from 265 classified buildings.

Attached on more than one side	42%
Attached on one side	54%
Detached	5%
Median building footprint	74 m²
Addresses per buildingAbove about 2 means flats and maisonettes dominate	1.47
Buildings classified	265

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 Cranford (TW5) 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
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

Sheet from a rear extension drawings package drawn for a Cranford property in TW5, showing the existing and proposed arrangement at scale — A sheet from the rear extension drawings package we submit to London Borough of Hounslow for Cranford (TW5) properties.

Also in Cranford TW5

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 Cranford TW5 — 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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