It’s that age-old conundrum for property owners, do you stay in your current home and make it work for you or do you buy a new property? Or as Kristy and Phil might ask, do you want to ‘love it or list it?’


With the cost of moving to a new house increasing all the time, not to mention the upheaval of the move, many people are considering staying put and extending their homes instead to get that extra living space they need.

In this guide, we’ll provide all the advice you need on home extensions, including securing planning permission, understanding building regulations, as well as information around costings, and tips on choosing your architect and builder.

Planning permission for extensions

The general rule is the larger and more significant improvements are likely to need planning permission from your local government. Whilst the smaller, less obtrusive improvements are likely not to require permission – this is known as permitted development.

As long as the plans for your extension adhere to the following rules, you won’t have to get planning permission for the work:

  1. The extension isn’t higher than the highest part of the roof of the house.
  2. If it’s a single-storey rear extension, it should not extend more than three metres beyond the original wall of the house, if a semi or terraced house, or four metres if a detached house.
  3. A two-storey or more extension should not extend more than three metres beyond the original wall of the house.
  4. The maximum height of a single-storey rear extension is four metres.
  5. A single-storey side extension should have a maximum height of four metres, and the width should be no more than half that of the original house.
  6. A two-storey extension has to be at least seven metres to the rear boundary.
  7. Materials used need to be similar or match the appearance of the house.
  8. No balconies or raised platforms

Be mindful that if you’re planning to extend a new build house, then you may well need permission from the developer who may also charge for this work.

Building regulations for extensions

Building regulations are a requirement for any type of extension and confirms that the work carried out is structurally sound, such as drainage, electrics, external and internal walls, roofs etc. Firstly, you will need to get the architect to draw up the plans that you can then submit.

To read the full list of planning permission and building regulations, visit the government website or contact your local council for more information.

How much is a house extension?

The cost of an extension will understandably vary depending on what you want and where you live. Generally, costs are worked out per square meter, for instance, a single-storey extension would typically cost around £1,000 per square metre. As such, if you were looking at building a 3x5m extension, it might cost around £15,000 for a single-storey, or up to £50,000 for a two-storey.

Once you know what sort of extension you’d like, the best thing to do is get a few builders to come over and quote you.

Choosing your architect and builder

When it comes to choosing your architect and builder, you’ll want to know that you’re using someone who is trustworthy and experienced. Afterall, you may well be about to spend a large amount of money on what might be your forever home. For that reason, we suggest you ensure you pick the right contractor, perhaps upon recommendation from friends and family you trust.

When finding an architect, you need to look out for signs that they’re listening to your exact needs. They’re going to be creating something that’s tailored to you so listening to your requirements is essential – just make sure you give them a good brief. An architect’s knowledge and expertise is also crucial as they can make good recommendations and help work around any obstacles that might stand in the way.

Many architects work with a network of builders, so are likely to be able to recommend a few if you don’t already have a builder. Similar to architects, you’ll want a builder who is experienced, so it’s worth asking to look at their portfolio to get an idea of previous jobs they have worked on and what their capabilities are. Also, prepare a brief for them so they know as much about the job as possible – share the architects plans if you already have them. Don’t be nervous about getting a few different builders round to give you quotes. And most importantly, be sure to check exactly what their quote includes and what the terms and conditions are.

When it’s time to make your final decision, weigh up the quotes with your allocated time scales. For instance, one builder might be cheaper than another, but has a four month wait time. Ultimately, it all depends on what is most important to you.

Funding your home extension

When it comes to funding the project, there are several options available. For instance, you can take out a loan for the house extension from your existing mortgage lender, or you could consider remortgaging.

If your current mortgage deal is due to come to an end, then it’s the perfect time to remortgage and use some of the equity you’ve built up to pay for, or put towards, the extension. By doing this, you can also take advantage of current low interest rates. Because of cheap interest rates, even if you already have the savings to fund the extension, you might decide to keep hold of this and use it for other things, such as saving for your children’s school or perhaps that holiday of a lifetime.

If you do choose to do an extension, make sure you spend a good amount of time planning it. The work you put in prior to the build will be well worth it in the long run.