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With spacious gardens, beautiful views, and relaxed rules, 3m rear extensions are a no-brainer. They not only add valuable space to your home, but can also bring in additional comfort and design to make your property even more appealing.

And with the best help and experts by your side, designing and creating the perfect rear extension becomes as effortless as you would imagine it to be.

As the name suggests, a rear extension is an extension that is constructed on the rear of a property. Given the relatively large area available at the rear of most properties, a rear extension is the most obvious and practical way to add substantial space and value to a home.

Rear extensions are broadly categorised into two main types; namely:

Single storey rear extensions

A simple and straightforward build, single storey rear extensions offer tremendous versatility to homeowners in their design and function. They are often utilised for the creation of kitchen extensions, guest bedrooms, and office pods.

Double storey rear extensions

Though more complex to design and build, multi-storey extensions are considered to be extremely cost-effective options as they help double the square footage of an extension without doubling the roofing and excavation costs. They also give rise to numerous design possibilities including bedrooms, bathrooms, or even high-ceilinged living and dining areas.

It’s unlikely.

3m rear extensions generally fall under permitted developments. However, they might require planning permission if:

  • They are constructed on flats, maisonettes, or properties listed in conservation areas
  • They exceed the height of the original house
  • They are less than 7m away from the rear boundary
  • They take up more than 50% of the garden/ outdoor space
  • The materials utilised differ in appearance from those on the existing house
  • They include balconies and/or verandas
  • Any upper floor windows in side elevation is not obscure glazed

For a comprehensive understanding of the requirements for planning permission and the specifications associated with permitted developments, property owners could also visit the planning portal.

Party wall agreements and building regulations approval must also be considered to ensure that the proposed home extension meets building guidelines and standards.

Though relatively small, 3m rear extensions offer a great deal of design opportunities that can help add incredible space, comfort, and style to your home. Some of the best ways to utilise the rear extension may be in the creation of:

  • Additional bedrooms
  • Bathrooms
  • Modern kitchen extensions
  • Open plan living areas
  • Playrooms/ study areas
  • Home libraries
  • Conservatory-style living areas
  • Alfresco-style dining areas
  • Office pods

In actuality, the use of this added space is limited only by your imagination.

To help make the most of this extension, and to ensure that the new build does not hinder the natural light entering your home, bi-folding or sliding glazed doors, and roof lights are a must. They not only help create bright and airy spaces, but also add a wonderful aesthetic of bringing the outdoors in.

The cost of a rear extension is dependent on the number of factors including:

  • The design/ complexity of the extension
  • Location
  • Groundwork involved
  • Building materials
  • Fittings and fixtures
  • Specialists’ fees, etc.

Therefore, the cost of a rear extension typically ranges from £20,000 to £70,000. However, the cost is largely made up by the value that the extension adds to the property.

Good Design and Build offer free consultations and quotations for proposed extensions. This allows homeowners to plan their home extension budgets and designs to their specifications.

The real question is why not?

Good Design and Build are the ultimate home extension specialists. With decades of experience, unmatched expertise, and utmost professionalism, we handle every extension process with care, responsibility, and accountability to give homeowners the home extension of their dreams.

Our brilliant team of surveyors, architects, engineers, builders, technicians, and project managers provide complete project management of the entire extension process from start to finish. This allows homeowners to enjoy their home extensions without any of the worry.

Good Design and Build create beautiful, bespoke rear extensions that add space and value to your property, while optimising the innate potential of your beautiful home.

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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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

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