Design & Planning

The order of events

Not sure where to begin with planning your side return extension? You are not alone. It can seem overwhelming to begin with, but once you understand the process, you’ll find things are actually pretty straightforward.

1. You need to decide whether to employ a company who will take care of the entire design and build – a one-stop shop – or whether you wish to employ individual contractors yourself. Do your homework and be sure to get at least 3 quotations. You may be pleasantly surprised by how a ‘one-stop shop’ solution can work out more cost effective for you (and certainly a lot less hassle).


2. Once you have appointed your design and build company or your architect and agreed on the schedule of works and the costings, you will design your plans and apply for any required planning permission (in the majority of cases, full plans are NOT required).

3. You will consult with your neighbours and ensure that any Party Wall Awards are in place.

4. Your structural drawings will be produced, enabling your chosen builder to build your extension safely and in accordance with building regulations.

5. Construction will begin on a mutually agreeable date and completed within approximately 12-14 weeks.

6. Once the build is finished, you can lay your floor, paint, install the kitchen and enjoy your new space!

The role of the architect

An architect is the first professional who will be involved in the process of planning a side return extension.

Your architect will discuss with you the design options you have. He or she will then measure up your space and provide drawings of both your existing and proposed plans, elevations and sections. They will also manage the planning application on your behalf (either ‘permitted development’ or ‘full plans’ depending on your circumstances – see planning permission for more info on this). They will continue to liaise with your local planning authorities until your permission (if applicable) is granted.

Typical designs

A side return extension is a modern and practical way to increase your ground floor living space. The majority of customers will use this style of extension to increase their kitchen/dining area – a space which is increasingly viewed as the heart of the home.

It is therefore important to maximise this area’s potential and to give your design very careful consideration before committing to a builder. Getting the design right at the start could save you a lot of grief (and expense) further down the line.

Typically, customers will either opt to extend to the side return alone, or to additionally extend outwards, increasing the depth of the ground floor space. The latter option usually costs around 10-15% more.

All work will involve building a new wall, approximately 2 – 3 metres high. Depending on what you agree with your neighbour, this wall will be built either straddling the boundary of yours and your neighbour’s land, or solely on your side of the boundary. A sloping roof will be built, with tiles to match the existing main roof.

Either skylights or Velux windows will be built into this new roof, to allow the light to flood in. The existing side wall will then be knocked through and a steel frame inserted to support the new opening. The floor will then be built up, to match the level of the existing one.

Planning permission

One of the first things you will ask yourself when planning a side return extension is whether or not you will need planning permission. In the majority of cases, full planning permission is not required.

For details on the current guidelines, please visit the government’s planning portal, or seek advice from your architect.

However, even if you do not need planning permission, you will need to obtain a certificate from your local council’s planning department, called a ‘Certificate of Lawful Development’. This document basically proves that you did not need full permission and can be invaluable when it comes to selling your home (as your future buyers’ solicitors will probably ask to see it).

Party Wall agreements

If you are building a side return extension, then you will need to consult with your neighbours and serve them with a Party Wall notice. They will then need to sign a Party Wall Agreement, before you can proceed with your works. Your architect will be able to assist you with this process. You are advised to read through the Party Wall Act to understand both your rights and the rights of your neighbours.

In essence, your neighbour cannot prevent you from building up to the boundary you share. However, if they have any reasonable objections, then a Party Wall Award may be necessary, and this will be determined by an agreed surveyor. This may take several weeks to be settled, so be sure to begin consulting with your neighbours as soon as possible.

Structural drawings

Once your architect has completed your plans, you will need to enlist a structural engineer to complete structural drawings (or, if you have chosen and design and build firm, they will manage this for you). These drawings are required by Building Regulations and they will enable a builder to make safe alterations to your property.

Building Regulations

Building Regulations apply in England & Wales and must be adhered to when making any alterations to your home. Building regulations ensure that building works are carried out safely, using the right materials to promote insulation and energy efficiency. They also take into account the needs of our population as a whole, ensuring those with disabilities will not have their access or ability to move around impacted by any alterations.

It is therefore a legal requirement that any side return extension project is approved before and during the project, by a qualified ‘Building Control’ professional.

You can choose to either use a building inspector via your local council’s planning department, or you can use a private, Approved Inspector.

If you choose a turn-key solution – a building company which project manages everything for you, such as Build Team – then they will take care of appointing an Approved Inspector on your behalf.

Design and Build Extensions with Us!

Side Return Extensions allows you to design and build extensions for your kitchens and living rooms with convenience beyond imagination. Once you send us your prospective design, our architects and renovation experts will give you an estimated cost of the job based on your requirements.

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