Crown Architecture & Structural Engineering
House Extension Plans in Merton
Extending a home in Merton requires plans that work within the constraints of the existing building, neighbouring properties, and Merton's local planning policies. Crown Architecture prepares house extension plans — from single-storey kitchen extensions to multi-storey side or rear projects — tailored to your specific property and the requirements of London Borough of Merton.
Project imagery
House Extension Plans in Merton — project examples
Residential project, drawing-package, and planning context imagery relevant to this service and borough.
Local planning context
Planning in Merton
Every street in Merton carries its own planning history — from Wimbledon to Mitcham — and a proposal that wins approval needs to be grounded in that local reality, not generic guidance.
Permitted development rights allow many extensions and loft conversions in Merton to proceed without a planning application, but the limits on height, depth, and materials are specific. A Lawful Development Certificate is the safest way to confirm the position, particularly for properties in conservation areas or affected by Article 4 directions.
Where a Merton project falls within permitted development limits, a Lawful Development Certificate from London Borough of Merton provides formal confirmation that no planning permission is required. This is particularly valuable in Merton where conservation area boundaries and Article 4 zones can affect rights that would otherwise apply, and where mortgage lenders and future buyers often require documentary evidence.
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Conservation Areas in Merton
If your property sits within or near one of Merton's 28 conservation areas, your application will be assessed partly on character, materials, and how it reads in the street scene. Conservation areas in Merton include Kenilworth Avenue, Lambton Road, Dennis Park Crescent, Drax Avenue.
Conservation area designation in Merton does not mean that development is not possible — it means that the design, materials, and overall approach need to demonstrate that the area's character is preserved or enhanced. Most extension and loft conversion types are achievable with the right design treatment.
Within conservation areas in Merton, London Borough of Merton planners assess householder applications against the Characterisation Studies or Design Guides published for each area. A well-referenced proposal that acknowledges these documents typically progresses more smoothly than one that does not.
- Kenilworth Avenue
- Lambton Road
- Dennis Park Crescent
- Drax Avenue
- Dunmore Road
- Bertram Cottages
- Wimbeldon Broadway
- Wimbledon Windmill
- John Innes (Wilton Crescent)
- Wimbledon Hill Road
- Pelham Road
- Wimbledon Chase
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House Extension Plans
Our extension plans service for Merton homeowners begins with a site appraisal that confirms the planning route, the permitted development envelope, and the likely constraints for the specific proposal. We present design options before fixing on the approach, so you can make an informed decision.
House extension plans for Merton properties need to address the specific constraints of the site: plot depth, proximity to neighbouring windows, the character of the street, and any conservation area or Article 4 designation that changes what is achievable.
Once the design is agreed, we take the extension plans through planning permission (or permitted development confirmation), building regulation approval, and the construction-issue stage, providing a coordinated set of information for each phase.
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Our Process for Merton Projects
Submissions to London Borough of Merton are made via the Planning Portal using the householder application form, accompanied by the full drawing set and any required supporting documents. We monitor the application throughout the assessment period, responding to requests for information and liaising with the case officer as required.
All projects in Merton begin with a free consultation call where we discuss the brief, the property, and the likely planning route. We then issue a detailed fixed-fee proposal before any survey or design work begins, so there are no surprises on costs.
- Free initial consultation and brief assessment
- Fixed-fee proposal covering all agreed services
- Measured survey of the existing property
- Design options and client review
- Planning drawing preparation
- Submission to London Borough of Merton
- Officer liaison and application management
- Post-consent building regulation package
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Why Choose Crown Architecture in Merton
Crown Architecture & Structural Engineering Ltd has worked across all 32 London boroughs including Merton. Our experience with London Borough of Merton's planning requirements, validation standards, and officer expectations means we can prepare applications that progress efficiently and with a high first-time approval rate.
We are a full-service practice — architecture, structural engineering, and planning consultancy under one roof. For Merton projects, this means the planning drawings, structural calculations, and building regulation package are all coordinated by the same team rather than produced by separate consultants whose information does not align.
Our registered office is at 71–75 Shelton Street, London WC2H 9JQ (company number 16297850). We are contactable at +44 7950 114633 and cover all projects across London and the home counties, including all areas of Merton.
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Housing Stock and Local Character in Merton
Merton is a south-west London borough combining the urban Wimbledon and Mitcham centres with quieter residential suburbs and significant conservation areas around the historic village of Wimbledon. This character shapes what planning applications are likely to succeed and how they need to be presented to London Borough of Merton.
The residential stock in Merton consists principally of Victorian and Edwardian terraces in the older centres, inter-war semis and detached houses in the suburban areas, and a mix of new-build and period conversions. Understanding how the existing building type responds to extension or alteration is the starting point for any design brief — it defines the structural approach, the planning sensitivities, and the opportunities for the project.
Key areas within Merton where we regularly work include Wimbledon, Mitcham, Morden, Colliers Wood. Each of these areas has its own micro-character, planning history, and in some cases specific conservation area or Article 4 designations that affect what is achievable on any given street.
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House Extension Plans — Further Information
Extension plans for Merton homes are most effective when they address both the planning question and the construction question simultaneously. A plan that wins planning permission but requires significant redesign for building regulation compliance wastes time and can cause costs to escalate. Our integrated approach coordinates both from the first design stage.
For Merton homeowners who are also considering loft conversion or basement work alongside an extension, we can prepare a masterplan that shows how all the works relate to each other — a useful planning tool both for staging the works and for showing London Borough of Merton the overall intention if the planning applications are to be submitted simultaneously or in sequence.
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Building Regulations in Merton
In Merton, building regulation approval is a separate process from planning permission, governed by the Building Safety Act 2022 and the associated Approved Documents. Building control or a registered inspector assesses the technical compliance of the works — structure, thermal performance, fire safety, accessibility, and drainage — independently of the planning assessment.
Building regulation approval in Merton runs in parallel to planning consent — they are two separate legal processes. We manage both for clients who wish to use Crown Architecture for the full project, or we can work alongside a client's own building contractor or structural engineer where preferred.
Common questions
House Extension Plans in Merton — frequently asked questions
Answers to the planning, design, and regulatory questions we are most often asked about House Extension Plans in Merton.
Can I build a two-storey extension in Merton?
Yes. Two-storey rear extensions in Merton require planning permission in most cases (only the rarest circumstances fall within permitted development for two storeys). London Borough of Merton assesses two-storey extensions against their relationship to the rear boundary, impact on neighbouring light, and the scale and design relative to the host building and street. We prepare the full planning application including a design justification where required.
Do I need party wall agreements for an extension in Merton?
If your Merton extension involves building on or near the boundary with a neighbouring property, excavating within three or six metres of a neighbour's foundations, or carrying out works to a shared wall, the Party Wall etc. Act 1996 applies. You must serve notice on adjoining owners before works start. We can introduce a party wall surveyor from our network to manage the process.
What is an orangery or extension and what planning applies in Merton?
Orangeries and conservatories attached to houses in Merton are generally treated the same as extensions for planning purposes. The key distinction for building regulations is whether the space is heated and thermally separated from the house — fully integrated heated extensions have full building regulation compliance requirements, while traditional glazed structures meeting specific criteria may have exemptions.
How long does it take to get planning permission for an extension in Merton?
From starting the drawings to receiving a planning decision in Merton, a typical householder application takes twelve to twenty weeks. This includes two to four weeks for drawings, one to two weeks for submission and validation by London Borough of Merton, and eight weeks for the application to be determined. Our programme is discussed and agreed at the start of each project.
How far back can I extend my house in Merton without planning permission?
Under current permitted development rights, a detached house in Merton can extend up to eight metres to the rear (single storey) or three metres (two storey) without planning permission, subject to the prior approval notification scheme for larger extensions. Semi-detached and terraced houses can extend up to six metres (single storey) or three metres (two storey) via the same scheme. These limits assume no conservation area or Article 4 direction applies.
What is the prior approval notification scheme for large extensions in Merton?
Under the neighbour consultation scheme, extensions between four and eight metres for detached houses, or three and six metres for other house types, can proceed as permitted development in Merton subject to a prior approval notification to London Borough of Merton. Neighbours are consulted and the council assesses the impact on amenity. Most applications are approved, but the process takes up to eight weeks from notification.
Can I extend my house in Merton if it is in a conservation area?
Yes, but permitted development rights are often restricted or removed in conservation areas in Merton. Rear extensions in conservation areas typically cannot exceed one storey and must use materials that match or complement the host building. In some conservation areas, even single-storey rear extensions require a planning application rather than being automatically permitted. We confirm the specific restrictions for your property as part of the initial assessment.
What is a side return extension and does it need planning permission in Merton?
A side return extension fills in the narrow strip of land at the side of a Victorian or Edwardian terraced house, typically extending the ground floor outwards. In most parts of Merton, side return extensions of a single storey can be built under permitted development, but in conservation areas they often require planning permission. The extension typically needs to be set back from the front elevation and use matching materials.
What is an under-build extension and does it need planning permission in Merton?
An under-build or basement extension involves excavating below ground level to create a new habitable space. In Merton, basement extensions almost always require planning permission and are subject to additional assessment around structural stability, flood risk, and impact on neighbouring properties. London Borough of Merton has specific policies on basement development and the drawings must address these comprehensively.
How do I know how big an extension I can build before planning permission is needed in Merton?
The permitted development limits for extensions in Merton depend on the property type, existing extensions, plot constraints, and whether any designations apply. We confirm the exact limits as part of our initial assessment — which is included in our design service. We will also tell you when a Lawful Development Certificate is advisable to formally confirm the position before or after works.
Who is the planning authority for Merton?
The planning authority for Merton is London Borough of Merton. All planning applications for residential and commercial developments in Merton are submitted to and determined by London Borough of Merton, which also provides pre-application advice and manages the planning enforcement function for the borough.
What types of development need planning permission in Merton?
In Merton, planning permission is required for: new buildings; extensions that exceed the permitted development limits; changes of use (e.g. from residential to commercial); demolition of protected structures; and any works that affect a listed building or its curtilage. Smaller extensions, loft conversions within volume limits, and outbuildings within the curtilage may fall within permitted development, but constraints apply in conservation areas and Article 4 zones.
Is Crown Architecture registered with Companies House?
Yes. Crown Architecture & Structural Engineering Ltd is registered at Companies House under company number 16297850. Our registered address is 71–75 Shelton Street, London WC2H 9JQ. We carry professional indemnity and public liability insurance appropriate to the scale of residential and small commercial projects we undertake.
What are the core contact details for Crown Architecture?
Crown Architecture & Structural Engineering Ltd can be reached by telephone at +44 7950 114633 or via our website contact form. Our address is 71–75 Shelton Street, London WC2H 9JQ. We cover all projects in Merton and across London and the home counties.
How does Crown Architecture price house extension plans services in Merton?
Our fees for house extension plans in Merton are fixed-price, agreed before any work begins. The fee depends on the scale and complexity of the project, whether conservation area or listed building constraints apply, and the scope of services required (planning only, building regulations, or combined). We provide a detailed fee proposal after a free initial consultation.
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