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This south-west London suburb has two halves to it. Family Clapham in the Old Town and around Abbeville Road with its large houses with gardens, and the more urbane young Clapham made up of its flats and swanky nightlife of the High Street. Whichever the Clapham you live in, if you want a house here, you want it to offer you the modernist’s space and comforts. We design and build house extensions Clapham imbued with inspiration. Our high-calibre period home remodelling has earned us a reputation as a trusted specialist extension service in London. As experts in Victorian and 1930s architecture, we devise the best space maximising techniques for truly transformative endeavours.

The Side Return – the feature that comes in handy for this extension is the narrow strip of land leftover by the rear outrigger at the side of Victorian and Edwardian homes. It borders the neighbouring property, and by enclosing this space with a new party wall, you add more space for a kitchen extension, a utility room, diner, WC/bathroom, or a garden room.

Rear Extension – by extending your floor area towards the back garden, a living space with a better connection to the garden gets created. You can build across the whole width of the property. It receives a flood of natural light and ventilation.

Wraparound Extension – if you have enough space, the complete Wraparound extension, forming an L-shape addition, makes the floor space longer and wider well-suited for open-plan living.

Loft Conversions – they provide the scope for a home extension without using up garden space to create a bedroom, en suite, playroom, home office, or an extra bathroom.

If you build within Permitted Development rights, you do not need planning permission. However, if your extension exceeds the specified limitations, you will need to apply for permission. Listed buildings and properties on designated land do not carry PD rights.

  • Extensions (including previous ones) must not exceed 50% of the total land area around the original house.
  • Single-storey Side extensions can be no more than half the width of the original house.
  • Single-storey extensions should be no higher than 4m.
  • Single-storey Rear extensions are more than 8m from the original rear wall of a detached house or 6m if the property is semi-detached or terraced.
  • Double-storey extensions extend more than 3m out from the original house and are closer than 7m to the rear boundary.
  • Double-storey extensions can only have obscured glazed windows at the side elevation. Unless the openable part is 1.7m above the floor, the windows must be non-openable.

Wraparound extensions and double-storey Side extensions almost always need planning permission. You must also get party Wall Agreements from the neighbours to carry out extension work. A homeowner must give written notice to your neighbour between 2 months and a year before you start work on your extension project.

  • A pitched roof works well with Crittall style doors and windows, especially for a rear extension.
  • A double-pitched rear extension makes spaces look formidable.
  • Your disused garage contains wasted livable space. A standard-sized garage can convert into an extra bedroom, en suite, or extended kitchen area.
  • A galleried two-storey glazed extension allows the existing rooms to receive a flood of natural light while offering more indoor-outdoor living space.

We create modern spaces with flexible designs for seamless integration and greater functionality. Our success is down to high-quality craftsmanship and accountability. We maintain transparency with costs and your budget and offer easy payment methods. The build team consisting of proficient structural engineers and skilled builders has extensive knowledge in building control guidelines and superior construction. We assist with Party Wall Agreements. Good Design & Build carries out planning permission submission and other pre-build paperwork as we constantly review guidelines for extensions in London. We also provide you with a project manager to coordinate and supervise work from start to finish. You also receive two separate no-obligation contracts for the design and build phases.

House extensions can cost between £1,000 – £2,000m².

A Side Return costs £35,000 and more

A Rear Extension costs £40,000 and above

Wraparound Extension will cost £55,000 and more

A Double story extension costs £75,000 upwards

Room in the roof loft conversion costs £1,150 – £1,350, a Dormer loft extension costs £1,250 – £1,450, a Mansard extension costs between £1,500 and £2,500, a Hip-to-gable extension can cost around £1,500 – £2,500, and change of roof structure costs £1,350 – £1,550.

Start design building your extension project with us today. Get help with home remodelling in the Clapham area for outstanding additions that afford maximum space.

Don't move. Extend in style

We can save you the hassle that comes with moving not to mention the heavy stamp duty! Adding an extra loft bedroom or enlarging the living kitchen dining space on ground floor is an economical way of transforming your home to suit growing needs. The projects can range from £40-100K depending on your requirements and can be completed within 8-16 weeks.

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How we deliver projects

Our process is simple and divided into two distinct phases with separate contracts: Design and Build. As a client you only commit to one phase at a time depending on what stage of the process you are in. Each phase consists of three stages as described below.

1. Design

This is the kick-off point for your project. We carry out a complete architectural measured survey of the property. This allows us to create accurate CAD design drawings. This is followed by a design meeting to start discussing your ideas in more detail.

2. Planning

At this stage we finalise the designs with you and start preparing planning applications as needed. We place a high priority on ensuring that plans, designs and schedules are all based on a thorough and detailed understanding of planning guidelines. We co-ordinate with local authorities until the decision is made, and the planning approval is secured.

3. Technical

Once the planning consent is secured, we translate the design drawings into more detailed technical drawings for the purposes of building control and construction. This also includes specifications and structural calculations. At this stage, we will also submit to you our ‘no obligation’ quote for the build phase.

4. Pre-build

90% of our clients decide to stick with us after the design phase is completed. Once the build contract is signed, we kick off the process by making sure all the pre-build processes are complete. These include assistance with party wall agreements, Thames Water build over agreement, submitting building control application, and preparing method statements etc as needed. This stage ends with a pre-start meeting with your foreman before the actual build begins.

5. Build

One of our foremen will be dedicated to your project and will be on-site to manage everyday works. Our project managers will be overseeing the works to make sure they are completed to high standards, within your budget and on time. Throughout the process we will keep you updated with the progress and coordinate the works with third parties such as kitchen or flooring suppliers. We will also advise and guide you to choose any suppliers if needed.

6. Handover

As the build draws to finish, we will help to iron out any ‘snags’ to make sure everything is completed to your satisfaction. We will put together all necessary certificates such as gas, electricity and building control completion along with warranties for glazing, boiler etc. At the final completion meeting, we will hand you these documents, together with the keys to your house. Needless to say, you can contact us any time after this, if you want us to look at something.


This is the kick-off point for your project. We carry out a complete architectural measured survey of the property. This allows us to create accurate CAD design drawings. This is followed by a design meeting to start discussing your ideas in more detail.

At this stage we finalise the designs with you and start preparing planning applications as needed. We place a high priority on ensuring that plans, designs and schedules are all based on a thorough and detailed understanding of planning guidelines. We co-ordinate with local authorities until the decision is made, and the planning approval is secured.

Once the planning consent is secured, we translate the design drawings into more detailed technical drawings for the purposes of building control and construction. This also includes specifications and structural calculations. At this stage, we will also submit to you our ‘no obligation’ quote for the build phase.

90% of our clients decide to stick with us after the design phase is completed. Once the build contract is signed, we kick off the process by making sure all the pre-build processes are complete. These include assistance with party wall agreements, Thames Water build over agreement, submitting building control application, and preparing method statements etc as needed. This stage ends with a pre-start meeting with your foreman before the actual build begins.

One of our foremen will be dedicated to your project and will be on-site to manage everyday works. Our project managers will be overseeing the works to make sure they are completed to high standards, within your budget and on time. Throughout the process we will keep you updated with the progress and coordinate the works with third parties such as kitchen or flooring suppliers. We will also advise and guide you to choose any suppliers if needed.

As the build draws to finish, we will help to iron out any ‘snags’ to make sure everything is completed to your satisfaction. We will put together all necessary certificates such as gas, electricity and building control completion along with warranties for glazing, boiler etc. At the final completion meeting, we will hand you these documents, together with the keys to your house. Needless to say, you can contact us any time after this, if you want us to look at something.

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Let's get started with building your own bespoke quote for your dream extension. Tell us as much in detail as possible to get most accurate price.

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Build a Quote!

Let's get started with building your own bespoke quote for your dream extension. Tell us as much in detail as possible to get most accurate price.

Get Started