Do You Need Planning Permission For A Loft Conversion?

Now and again when I’m showing people around nice houses, they’ll ask me: “Do you need planning permission for a loft conversion?”

Interestingly, the answer to this question has changed over time. It used to be that extending a house by as little as 10% required planning permission, however the government started relaxing these rules in October 2008.

Estimating that extensions can add 12% on average to the value of a property, the theory at the time was that changes to the law could also save up to £50m a year nationally. It would take a quarter of all householder applications – approximately 80,000 per year – off the planning system.

But that was then and this is now! This guide covers whether you need planning permission for a loft conversion, at the time of writing in 2023, plus what else you need to know before extending a property in this way.

Do you need planning permission for a loft conversion?

In short, often loft conversions do not need planning permission in the UK. Why?

It’s because in most cases, ‘permitted development’ laws will allow for a loft conversion without planning permission.

However, there are some crucial caveats. Later on I’ll cover some of the criteria affecting when loft conversions don’t count as permitted development.

There are other important considerations beyond planning permission for loft conversion extensions too, including UK building regulations.

Permitted development

There have been plenty of changes to permitted development rights in the UK over the past few years.

After the government got the ball rolling in 2008, the next piece of legislation worth reviewing is The Town and Country Planning Order 2015. For an official interpretation, check the stance on loft conversions from Planning Portal, a joint venture including the Department for Levelling Up, Housing and Communities.

It confirms that a loft conversion counts as permitted development subject to a few specified limits and conditions, too many to list here in full. These include, but are not limited to, the following.

The extension must not:

• Exceed the original roof space by 40 cubic metres on terraced houses
• Change the eaves of the original roof
• Be set back less than 20cm from the original eaves
• Use materials differing in appearance from the original house
• Be for a property on designated land (more on this later)
• Overhang the outer face of the wall
• Add a veranda, balcony or raised platform

Any windows facing the side need obscure-glazing, which stops people from looking into the loft conversion. If they open, windows need to be 1.7m above the loft floor too.

For some technical guidance, this is the government guide to permitted development rights – the Class B section covers roof additions, including lofts. Also bear in mind that there is a limit to how many changes a property can go through under permitted development rights.

After further changes to permitted development rights in 2020, now it is easier to potentially fast-track the addition of one or two storeys on some buildings. As always, conditions apply. 

Building regulations

Any loft conversion must still comply with UK building regulations.

The building regulations help ensure that any construction work is safe in terms of structure, fire resistance and so on. A planning consultant or architect can advise on all the appropriate building regulations and how to meet them.

For a loft conversion, relevant building regulations cover but are not limited to:

• Support for the additional weight e.g. floor joists or beams
• Fire safety e.g. fire-resistant doors and smoke alarms
• Sound insulation
• Thermal insulation
• Stairs

The specific regulations you need to adhere to depend on the type of loft conversion you’re aiming for.

When planning permission is required for a loft conversion

In some circumstances, you will need planning permission for a loft conversion.

Earlier we looked at some of the permitted development rules. If your loft conversion plans do not follow the rules, then you will need planning permission.

For example – installing, altering or replacing a chimney above the loft does not count as a permitted development. Also, a mansard loft conversion often raises the walls and roof height – this type of work would require planning permission.

There are several specific restrictions to permitted development rights. And if you’re thinking about a loft conversion on top of a flat, the situation becomes very complicated.

This is due to matters like who owns the overall building, share of freehold versus leasehold considerations and if the roof space needs to be altered. Also take a look at our article covering flying freehold considerations.

The permitted development rules also mention ‘designated land’ – keep in mind that if you live in a conservation area, regulations around building work tend to be stricter.

This short guide from Historic England explains why, plus how to find out if you live in a conservation area and who to contact about making changes to your home.

Other permissions for a loft conversion

Speaking of conservation areas, watch out for protected species! If you think there are bats living in your loft, you’ll need to conduct a survey.

Ultimately, you may require a migration licence if your loft is housing bats or other protected species. Here is the government policy on planning decisions when there are bats on site.

Make sure you tell your home insurer before carrying out any changes affecting the structure of the house.

Don’t forget about your neighbours either. Recently we also wrote about the circumstances when you require a party wall agreement. 

A party wall is a shared property boundary on the land of two or more homes. If your loft conversion affects a wall between two houses, you must provide neighbours with a party wall notice in good time and seek their agreement before starting any work.

Summary: Planning permission for loft conversions

Loft conversions do not need planning permission in the UK if they comply with permitted development laws.

However, any loft conversion not meeting the requirements of permitted development rules will need planning permission.

And of course, all loft conversions must adhere to building regulations. You may also need a party wall agreement.

I hope you found this article useful. Elsewhere on our blog there are plenty of other articles that could help you as a property owner or occupier.

If you have any questions or would like to ask about a property in our portfolio, we are here for you! Please do not hesitate to get in touch.