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How large a home extension do you need to build?

A few weeks ago, the permitted development regulations changed, allowing homeowners to build larger single storey rear extensions onto their homes. This means that you can build an extension 8m from the rear of the original house if it’s a detached house and 6m for all other houses, without having to go through the formal planning process.

Yippee, I hear you say!! Well, yes, in theory it is great news that building extensions is becoming easier and there’s less bureaucracy to deal with. However, just because you can extend further doesn’t always mean you should.

We’ve been working with a few clients on their extension designs recently and although you would assume that bigger is always better when it comes to space, that isn’t always the case.

How Large Does Your Extension Need To Be? - Fresh Start Living

Here are 5 things to think about before you embark on super-sizing your home

You need balance between the ground floor and upper floors of your home

Building a 6m extension at the back and creating a fantastic kitchen/dining/living space on the ground floor might solve lots of problems with the living space. But if you’ve only got 2-3 bedrooms on the first floor then it’s going to feel ‘bottom heavy’.

If you’re creating a large family space at the bottom, then from a resale perspective it needs to deliver bedrooms that fulfil a family’s needs too.

Balance Both Ground Floor And Upper Floors - Fresh Start Living

You don’t want to gobble up all the outside space

If you’re not blessed with a huge plot, then building a 6-8m extension is going to significantly impact your outside space. Similar to the first point about balance of ground and upper floors, you also need balance between inside and outside space.

Limiting your extension to 3-5m may still give you what you need whilst still retaining a good-sized garden. Again, if you own a family-sized home there needs to be space for children to play outside.

It's important To Keep Your Outdoor Space - Fresh Start Living

What will the extension be used for? Does it just create a large dead space?

6-8 metres on a house that’s already 6 metres wide means you’re creating in excess of 35 square metres of additional internal space. Considering the average new build home has 67.8 square metres of total living space (including bedrooms and bathrooms), that’s pretty huge.

You need to think about what an extension will be used for and whether it can create the right spaces for the way you live. It’s very easy to draw a big box at the back of the house but if it doesn’t have a purpose or can’t be zoned in the way that you live your life then it’s not worth the investment and effort.

Are there any other constraints on the size and shape?

Depending on the size of your plot, you may find the extending to this extent means that you’ll be building close the boundary. There are restrictions on the eaves height that you can build to on the boundary which may affect your design and what might be possible.

You can get around some of these issues by building a smaller extension or you cut off/into a corner of the extension to get around the boundary issue. However, this usually means that you need to be clever with the use of the internal space, making sure that your living space isn’t compromised by the structural changes.

Bigger Means More Expensive - Fresh Start Living

Bigger means more expensive. Just because you can, doesn’t mean you can afford it!

Although this is our last point, it’s by no means the least important. Building work is not cheap and most of our clients have a limited budget. So, although it might be easier to say “Let’s build a 6m extension rather than a 4m one just to make sure there’s enough space”, the impact on the basic build cost of that decision is in excess of £20,000. So, you need to be sure that you need that extra space and you need to know that you’ve got the money to fit that space out as well.

Hopefully this has given you some food for thought when it comes to deciding how large to build a new extension. But if you need more details on the regulations you can find them here. And, don’t forget you’ll still need to get Building Regulations sign off, even if you don’t need to go through the formal planning process.

If you are thinking about building an extension on your home and need some help or inspiration, do get in touch with us here. And don't forget to follow us via Instagram, Facebook and our upcoming blogs.

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