Rear extension on a Victorian house near Cricket Green, Mitcham, London Borough of Merton

Mitcham · CR4 · Merton

Rear Extension Drawings in Mitcham CR4

Fixed-fee, MCIAT-chartered rear extension drawings for Mitcham (CR4) homeowners — London Borough of Merton validation and local constraints handled from the start.

Mitcham (CR4) wraps around two historic open greens, so extension and loft projects here sit against a genuinely old-London backdrop of Georgian houses, almshouses and the Vestry Hall rather than uniform suburb.

Because the Cricket Green and Lower Green West Conservation Areas plus an April 2023 Article 4 direction overlap much of CR4, we always check the exact boundary before advising permitted development versus a full householder application.

Proposed floor plan

Mitcham CR4

Mitcham (CR4) — planning at a glance

Council: London Borough of Merton
Postcode district: CR4
Planning portal: View the Merton planning portal
Housing stock: A rare surviving cluster of Georgian and early-Victorian houses, almshouses and the Vestry Hall frame Cricket Green and Lower Green, giving way to Victorian terraces and interwar semis on the surrounding CR4 streets.
Article 4: Merton confirmed an Article 4 direction across seven wards including Cricket Green in April 2023, removing permitted-development change-of-use rights for certain commercial and community premises; it does not restrict routine house extensions but flags a heritage-sensitive setting.
Conservation: Mitcham Cricket Green Conservation AreaLower Green West Conservation Area
Sample streets: Cricket Green · Lower Green West · Madeira Road · Cranmer Road
Local constraints: Mitcham Cricket Green Conservation Area (designated 1969, extended 1990) covers 52.7 hectares and tightly controls alterations visible from the greensSeveral listed buildings and the war memorial near Lower Green West raise the bar for materials and detailingThe April 2023 seven-ward Article 4 direction signals a protected setting even where householder permitted development still applies

Planning in Mitcham (CR4): what to know before you apply

Homes inside the Cricket Green or Lower Green West Conservation Areas need a full householder application with a heritage justification; those on outer CR4 streets can often use permitted development, subject to a boundary and Article 4 check first.

Typical Mitcham housing stock

A rare surviving cluster of Georgian and early-Victorian houses, almshouses and the Vestry Hall frame Cricket Green and Lower Green, giving way to Victorian terraces and interwar semis on the surrounding CR4 streets.

Streets we regularly draw for in Mitcham

Cricket Green · Lower Green West · Madeira Road · Cranmer Road

What CR4 is actually built of

Measured from 335 classified residential buildings in CR4, not from a description of the area.

Mitcham CR4 housing mix

Residential building form across the CR4 postcode district, from 335 classified buildings.

Attached on more than one side	59%
Attached on one side	37%
Detached	4%
Median building footprint	55 m²
Addresses per buildingAbove about 2 means flats and maisonettes dominate	1.44
Buildings classified	335

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 Mitcham (CR4) 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 Mitcham property in CR4, showing the existing and proposed arrangement at scale — A sheet from the rear extension drawings package we submit to London Borough of Merton for Mitcham (CR4) properties.

Also in Mitcham CR4

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

FAQ

Rear Extension Drawings in Mitcham CR4 — 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 Merton?+

The interwar semis of Raynes Park and Morden often keep permitted development rights for rear extensions and lofts, so a full application isn't always needed. Conservation areas such as Wimbledon Village, Wimbledon Common and the John Innes estate at Merton Park restrict this. We check your street's designation first and can confirm permitted development with a Lawful Development Certificate.

What is special about building at the John Innes estate in Merton Park?+

The John Innes estate is a planned Arts-and-Crafts conservation area with a distinctive character the council protects closely — materials, proportions and rooflines are all controlled. Permitted development is often restricted there, so we design to the estate's character and prepare a full, context-led application, which is the reliable route to approval.

What do Merton's HMO Article 4 directions affect?+

In designated wards, an Article 4 direction removes permitted development for change of use to an HMO (C3 to C4), so a conversion to a house in multiple occupation needs a full application there. It doesn't affect a standard family extension, but if you are considering an HMO we confirm whether the direction covers your address and use before advising.

How long does Merton Council take to decide?+

Merton determines most householder applications within the statutory eight-week period once validated; Wimbledon and Merton Park conservation 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 Merton?+

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 Merton approves. A suburban Raynes Park extension and a Wimbledon Village or Merton 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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