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How to plan a side return extension

Image of a kitchen created by @imperfectinteriors

How to plan a side return extension

If your terraced or semi-detached house has retained its original kitchen, it’s probably a small, narrow space tucked away at the rear of the house. To increase its footprint, a popular solution is to extend into the narrow strip of garden – known as the side return – adjacent to the kitchen. By reclaiming this space, you can create an open-plan kitchen and family room without sacrificing much of the garden. Read on to find out a bit more about the rules and regulations around planning a side return extension.

Do I need planning permission for my side return extension?

Not usually, provided it satisfies certain criteria. For example, it must be single storey, no more than four metres high and a width of no more than half of the original building. Check out Planning Portal for more information on the criteria to meet.

That said, if your house is in an Area of Outstanding Natural Beauty or a Conservation Area then you may need to request planning permission. This could also be the case if your property is listed. If you’re unsure, speak to an architect or consult your local council.

Image of a side return extension in the kitchen of @1894home
Image: @1894home.
What do I need to know about building regulations when planning a side return extension?

Most side return extensions need building regulations approval to ensure the doors, windows, drainage, electrics and walls are compliant. You’ll also need building regulations approval if you’re adding a kitchen, bathroom or roof as part of the project. For further details, head over to Planning Portal.

What type of building regulations application do I need for my side return extension?

There are two possible ways to get building regulations approval: a building notice or a full plans application. If the work you’re planning isn’t complicated, you can submit a building notice to your local authority. You won’t need to supply detailed drawings for approval so work can start quickly.

If you need to have your plans approved before work begins, submit a full plans application to your local authority. You’ll need to do this well in advance of when the work is due to start. The advantage of this method is that potential problems can addressed before work begins, avoiding costly mistakes later on.

What do I need to know about party walls when planning my side return extension?

If you’re planning to dig foundations close to a neighbour’s property (within three or six metres, depending on the depth of the new foundations), it’s likely that you’ll need a party wall agreement. Have an informal chat with your neighbours before you kick this process off: it could make them more amenable to the works. Then serve them with a party wall notice – you can download free letter templates (which often include letters of acknowledgement for neighbours to complete and return) from the HomeOwners Alliance. Your neighbours will have 14 days to respond in writing. If you’re concerned about disputes down the line, appoint a party wall surveyor for a flat fee.

I’ve served a party wall notice on my neighbours but they’re refusing to sign it – what can I do?

If you can’t reach an agreement with your neighbours, you’ll need a party wall award. Both you and your neighbour can appoint an agreed surveyor to act impartially for you. He or she will produce a legal document that details the work being done and the rights and responsibilities of both parties.

How important is it to introduce natural light to my side return extension?

It’s very important: natural light will make your side return extension a far more appealing space. Think about large roof lights or a partially or fully glazed roof to link your side return with Mother Nature. A floor-to-ceiling fixed pane on the rear elevation works just as well or, if you want easy access to your garden, bi-fold doors, sliding patio doors or traditional French doors will let you step straight outside.

What is a rolled steel joist (RSJ) and why do I need one in a side return extension?

Part of the external wall of your home will be removed to create your side return extension and this wall is a load-bearing one: it supports the structural weight of the entire building. You’ll need a rolled steel joist to support this weight once the wall has gone – otherwise your house could fall down!

The RSJ will be visible inside and what you do it depends on your budget and the look you want. Cheaper options are to box it in or leave it exposed. If you have more cash to splash, you could create a flush ceiling with the steel beam recessed within the floor void above. (For more on RSJs, check out our guide to removing an internal wall, part two).

I’ve decided to leave my RSJ exposed. What do I need to know?

Building regulations state that an RSJ must be protected against fire. So, if you don’t want to box it in with plasterboard, you’ll need to paint it with fire-retardant paint (try Rawlins Paint).

Featured image: Seen in a family home in Barnes, London, this stunning side return extension was created by Imperfect Interiors.

Want more? Then don’t miss our in-depth two-part guide to removing an internal wall, part one is here and part two here.