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How to extend your home into your loft without the need for planning permission.

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For extra room in your home, and sometimes a great terrace, too, going up into the roof space is generally a cost-effective idea. You can usually do it if you either own the house, or the top floor plus rights to the roof space — as long as there’s enough head height up there. 

Listed homes are more difficult to get consent for but not always impossible. You’ll need a structural engineer to make sure the building can support the extra weight. They can also calculate structural changes to make sure that it does, if required.

Permitted development rules make a loft conversion much easier (because you don’t need planning permission), but you’ll still need a “completion certificate” to show that the work complies with building regulations.

This is issued by your local council’s building control department. In some cases, your project might fall outside permitted development, in which case you will have to go through the planning process before work starts. 

A loft extension is almost always faster and cheaper than digging out a basement, which will include excavating and underpinning. And unlike a basement, the work can sometimes be done while you are still in residence.

Once finished, the extra light and views a loft offers are a bonus. You may also be able to improve your home’s overall insulation while you are at it.

Plenty of companies specialise in loft conversions but all architects can design one — and come up with innovative ideas. Using an architect makes particular sense if you combine extending upwards with other changes to your home (new stairs, for example).


A loft conversion usually comes under “permitted development” (ie, you don’t need planning permission) but special rules govern conservation areas and “listed” buildings. To stay within the rules you need to ensure:  

  • The existing roof height won’t be raised and the front of the building won’t be significantly altered (the back usually can be changed but check your local council’s rules).
  • No more than 50 cubic metres is being added to a detached or semi-detached house, and only 40 to a terrace house. This includes any previous loft additions.
  • There is 2.1 metres of head-height in a good part of the main area. This is sensible, but it doesn’t stop you putting a loo or bathroom under a sloping eave — ie, where less headroom is needed.
  • If you want a balcony or terrace, you will need planning permission. 
  • You obtain a “completion certificate” from your council after the work is done to show your new loft complies with building regulations and fire-safety rules.
  • We here at 4dplanning can assist you with all that you need.

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