Are Loft Conversions Permitted Development?




are loft conversions permitted development

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In most cases converting your loft is considered to be permitted development because the impact of the works on neighbours is considered to be small. This means you don’t have to go through the planning process when you build a loft conversion.

There are however some caveats to this. The dormer can’t be front facing, cannot exceed the height of the existing ridgeline, and you can’t add a balcony. If your plans include any of these things, you must apply for planning permission.

We’ll go into what is and what isn’t allowed under permitted development in more depth shortly. But first.

What is permitted development?

It’s basically an easier and more convenient version of the planning regulations. The intent of permitted development is to make it easier for homeowners to make improvements to their property without having to navigate through the tortuous planning laws.

Permitted development covers most home improvement projects including loft conversions, but also includes other extensions, windows, and solar panels. But it’s important to realise that if you live in a listed property, area of outstanding natural beauty etc then permitted development does not apply.

How does permitted development affect loft conversions?

It’s meant that most homeowners no longer must worry about the planning laws when they convert the loft. This has made the whole project easier for many homeowners who are planning a loft conversion.

As we mentioned at the top of the page there are some loft conversions which will fall outside permitted development. When this is the case the homeowner will have to apply for planning permission.

But let’s clarify exactly what is and what isn’t allowed for loft conversions under the permitted development guidelines.

When is a loft conversion not permitted development?

As we’ve said, the good news is that most loft conversions will fall under permitted development, and you won’t have to worry about obtaining planning permission. But let’s clarify what is and is not required under the permitted development rules.

1 – In order to prevent the addition of overbearing dormers, volume caps remain in place for loft conversions. Up to 50 cubic metres can be added to the roof space of a detached or semi-detached house falling to 40 cubic metres on terraced properties.

Something to consider is that these volume caps apply to the property as a whole, not just the loft conversion. And they apply in relation to the original property.

If you (or a previous owner) have previously built an extension for example – that will be added to the loft conversion. If the combined volume of the extensions is more than the permitted development limits (above) then you will need to go down the planning route.

2 – Dormers will not be permitted to the elevation of any roof that fronts onto a highway.

3 – Any extension should be no higher than the ridge line of the existing property

4 – Dormers should be set back from the eaves by a minimum of 20 cm.

5 – Verandas, balconies or raised platforms will not be permitted.

6 – You must obscure any side-facing windows and be unable to be opened – unless they are 1.7 metres above the floor level.

7 – Any building materials used must be the same or like those used on the rest of the property.

If a proposed conversion falls outside of these guidelines it will not necessarily be refused permission but a full planning application will be required.

The changes mean that most loft conversions now fall within permitted development.

Is permitted development the same as building regulations?

No, they are not the same thing. Permitted development is a simplified and more accessible version of the planning laws which determines whether your loft conversion can be built but the building regulations lay down the standards which your project must comply with when built.

You cannot build a loft conversion (legally anyway) without adhering to the building regs and obtaining building regulations approval from the local authorities building control officer.

The building regulations lay down criteria for the actual build itself and mainly cover:

Structural changes.
Fire safety.
Ventilation and windows.

You can discover more about the loft conversion building regulations in this article.

So, red tape wise when we are thinking about converting the loft, we have to take into account the permitted development rules, planning permission, and the building regulations. Anything else?

Well. As a matter of fact. Yes, there is. We need to throw the Party Wall Act into the mix.

Party wall agreement

Even if your loft conversion falls under permitted development rights you will still need a party wall agreement should you be in a semi-detached or terraced property and share a party wall with a neighbour.

Although this does seem like another big obstacle to overcome it’s really not too much of an issue.

Read this article on the Party Wall Act for a detailed explanation, but basically you need to give your neighbours two months’ notice before the work begins. Your neighbours must respond within 14 days.

Usually, party wall agreements are plain sailing but if your neighbour believes your loft conversion will negatively affect their property, they can apply for an injunction preventing the work. And yes, they can do this even if you have permitted development rights.

How did permitted development come about?

Up to 80,000 more householders will be removed from the planning process each year following changes to the planning laws that first came into force way back in 2008.

The number of families wishing to add space to their home has grown year on year since the last property boom took off in the mid-1990s.

As a result Local authorities have been struggling to deal with the volume of planning applications within the allotted 8-week period.

The Government’s answer has been to change the rules so that the majority of domestic extensions will not now require an application for planning permission.

The most significant change is the removal of any tie-in between the volume of the original house and the permitted volume of the proposed extension.

The criteria will now be a set of guidelines governing the dimensions of the extension. We’ve discussed the main guidelines for loft conversion permitted development but what about other home improvement projects?

Here’s a quick summary.


  • Single storey rear extensions to detached properties can be up to four metres deep and four metres high.
  • For attached properties, and all extensions with two or more storeys, the maximum depth is reduced to three metres.
  • Multi storey extensions should be no higher than the roofline of the existing property.
  • Side extensions to be single storey only, no more than four metres high and no wider than half the width of the original property

Volume caps on rear and side extensions have been removed.

All the measurements should be taken from the ‘Original Property’ which for the purposes of planning matters is taken to mean the property when it was first built or on 1st July 1948 if it was built prior to that date.

If a property is listed or is located within a designated Conservation Area further restrictions will apply. In addition, Local Authorities can change the rules at a local level using either Development Orders of Article 4 Directions

Regardless of whether an application for planning permission is required all domestic extensions require building regulations approval and if the work will affect a wall that is shared with a neighbour it will fall within the scope of the Party Wall Act 1996. The Act requires householders planning to carry out alterations to notify any affected neighbours.

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