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Single storey side extensions: everything you need to know

5 min read
Oct '25 • by Heather

Quick summary

A single storey side extension in London costs roughly £45,000 to £195,000, depending on size, materials, and finish, with prices outside London starting around £37,000. It can be built relatively quickly once approved, fitting within permitted development rules if it’s under four metres high, one storey, and no more than half the width of your home.

If you’re thinking of increasing the living space in your home and you’ve some extra land on the side, it’s worth considering a single storey side extension.

They’re a great way to expand your kitchen or add that extra room you’ve been longing for. You could also turn it into a children’s playroom or knock down some walls to extend your living area.

Want to find out more about installing that side extension? Get your free Resi quote here.

Suppose you’ve been wondering about extending your home but have yet to decide how to go about it. You’re in luck. In this post, we'll cover the benefits of a single storey side extension, the cost of installation, building regulations, permissions, and, of course, some fantastic ideas on turning your side extension into your dream space.

What are the benefits of a single storey side extension?

  • Adds values to your home when done right
  • Presents the opportunity to remodel and renovate the home as you wish. You have complete autonomy and can decide on what you want to achieve
  • Increases your living area. You can use it as an extra room bathroom or decide to knock down a wall and extend a space, for example, maybe the kitchen
  • It helps you maximise the space at the side of your house
  • You don’t have to worry about losing prime bits of land since the space at the side of a home isn’t as well used as other garden areas

How much does an architect charge?