Side return extensions

When you work with a Resi architect, you can make it clear that your aim is to keep costs down, so this can be reflected in your design. Some ways to make your side extension more cost effective include:

• Building a single storey side return rather than a double storey. Sticking to one floor makes the build simpler, more compact, and usually on the more affordable side.
• Work with existing layouts and utilities. If you don’t need to move plumbing, gas, or electrical setups, that will save on extra work and minimise costs.
• Keep things simple. By reducing the amount of glazing or skipping fancier, more complex features, you might have a better chance of coming in on a budget. A minimalist, well-designed extension can look great while cutting unnecessary costs.

Side infill extensions rarely pass as permitted developments, which means you’ll probably have to apply for planning permission for your project. Some things to keep in mind ahead of your application include:

• Making sure the eaves on the boundary wall are not at a height that impacts your neighbours’ light or amenity.
• Making sure the depth of the side return extension isn't so long that it creates a crowding feeling for your neighbour.
• Making sure that your drainage is designed sensibly so that the water doesn't run off your roof and into your neighbour's land.

When planning your design with a Resi architect, they’ll take into consideration factors like these and more to give you the best chance of getting your planning permission application approved.

Extending your home in any way is a big decision. But ultimately, deciding whether a side return extension is worth it for you involves weighing up the pros and cons. First, consider the cost of the project, as well as the temporary disruption to your home. Then balance that against the long term value having more space will bring, both in terms of how you use your home, and in the property’s worth.

As side return extensions are most commonly found in Victorian terraced houses, the newly created space typically comes close to your party wall. If you’re not clear on what that is, it’s the boundary shared by you and your neighbour.

Any work done on the boundary line means you may need to apply for party wall consent. In this case, you’ll have to tell your neighbours about it at least two months before you start. If your neighbours give written consent to your extension, you won’t need a party wall agreement. But if they don’t reply, or they write back in disagreement, you’ll need to have a party wall agreement drawn up. This needs to be done by a party wall surveyor, which the Resi team can introduce you to.

Side return extensions are usually found in Victorian terraces, which are commonly laid out with a living room at the front, a dining room behind that, and then a long, narrow kitchen at the back. Where the kitchen doesn’t extend across the full width of the house, it leaves an alley of space which is what’s filled in with a side return extension. In the process, the dining room (or the middle room) can be at risk of losing its natural light if you don’t opt for a totally open plan layout.

However, smart design choices can keep your middle space bright and welcoming. One way to do it is to incorporate rooflights or even a full glass ceiling to channel daylight from above. You could also use glazed doors or large windows on the extension's outer wall to bounce light deeper into your home. Alternatively, you could work with your architect to think cleverly about your new floorplan, putting functional rooms that don’t require natural light (such as a downstairs toilet or utility room) in the middle portion of your home, leaving the more social spaces with natural light. Alternatively, you could consider adding in an external courtyard to bring in more daylight.

Adding value is often a key reason people decide to extend their homes. However, there’s no guarantee how much value you’ll add, with lots of factors coming into play, like the size of your house and where you live.

But to give you a rough estimate of how much value you could add with a side return extension, Resi’s data suggests you’re looking at an average of 3%. For a better idea of how much you could increase your property’s worth by, try Resi’s free extension valuation calculator.

Every project is different, so there’s no set timeline for a side return extension. But as a rough guide, any type of home extension in the UK usually takes somewhere between 7 and 15 months from start to finish. It looks something like this:

• Prep: 2-4 weeks
• Design: 2-5 weeks
• Planning: 8-10 weeks (minimum)
• Technical design: 4-8 weeks (building regs and structural engineer)
• Party wall agreement: 2-12 weeks (depending on your neighbours, not everyone needs one of these)
• Tender process: 3-6 weeks (hiring a building contractor)
• Building: 2-6 months (depending on how big the job is)