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Celebrating a vibe of village-like hospitality, Mortlake has been a historical suburb since the early part of the 17th century renowned for its exquisite tapestry work. Embraced by greenery and the calming Thames, Mortlake is famous for its periodic residences. The independent shops and restaurants are inviting to families and the suburb offers entertainment to all age groups. As a team specializing in building work on periodic houses, Good Design and Build is experienced in house extensions Mortlake as we create homes with historical architecture and a touch of modernity.

Single-storey extensions or two-storey extensions can be built to gain space based on your land footprint.

Side Return – the space alongside a Victorian or Edwardian outrigger is narrow and shaded and usually only reserved for the bins. The infill of this space forms a Side Return that extends the area to the party wall. The new volume can join the property to form a kitchen extension or other functional space you require.

Rear Extension – it produces a light-drenched, boundary-blending living space that is ideal for open-plan concepts. With an overlapping kitchen/dining/sitting area, you can create a social space fit for entertaining guests. You can also separate the new space with partition walls.

Wraparound Extension – the Wraparound design builds an L-shaped structure with a Side Return and Rear extension combined to enlarge the house footprint sideways and lengthwise.

Double-storey Extension – this type of extension is a cost-effective addition that allows you to generate floor space with the same roof and foundation. You can add a bedroom upstairs or dining/living space with glazed walls for maximum views.

Your average house extension does not need planning permission as it is considered a permitted development by law. It should also comply with building regulations. There are, however, conditions that remove PD rights, and they include;

  • The property you are building the extension for is within a designated area or a listed building.
  • The extension covers more than 50% of the land area of the property
  • Single-storey Rear Extensions extend more than 8m from the original rear wall of the property if it is a detached house and 6m if it is a semi-detached or terraced property.
  • A single-storey extension exceeds the permitted 4m height.
  • Double-storey extensions are closer than 7m to the rear boundary.
  • The extension exceeds the highest part of the original roof and is higher at the eaves.
  • The roof pitch and exterior differ from the existing ones.
  • There are balconies, raised platforms, and verandas.
  • The extension is forward of the principal elevation, or where it fronts a highway, the side elevation.

Loft conversions – they add magic to interiors in the roof without taking up garden space. You can combine a single-storey extension with a loft conversion to build outwards and upwards for two different extension types.

Asymmetry – a Side Extension that doesn’t come in line with a Rear Extension affords more natural light and appears more inclusive to the architecture. With an overlapping patio area resembling the extension floors, two areas blend into one.

Earthly tones and textures and living walls and roofs add nature-inspired harmonious elements to an extension. Consider a roof terrace with plants and vines and wooden seating. Break down barriers to nature as much as possible and incorporate the surrounding nature into the interiors through transparency and architectural lightness.

Undertaking building work for decades, our expertise as a building company puts us at the forefront of period home remodelling in London. The specialised knowledge we have gained in home extensions in Mortlake allows us to create authentic designs that complement your property and your needs without overshadowing original architectural integrity. With professional architects, structural engineers, and a qualified team of builders on the job, every aspect of the creative process entails precision and quality. We provide planning assistance and pre-build necessities by undertaking all admin including, submitting applications, preparing method statements, and assisting with Party Wall Agreements. You will only sign individual contracts at the start of design and build stages and not a thumping contract at the very beginning.

The costs vary due to the size, the intricacy of the design, and the preferred material. The average cost of a single-storey Side Return is £35,000, a Rear extension is £40,000, and a Wraparound extension is £55,000 and above. A double-storey extension starts from £75,000 onwards.

Get a free quote to build free-spirited extra space for your house in Acton from Good Design & Build.

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