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  1. Blog
  2. Do you need planning permission for a loft conversion?
Add value to your home
21 August 2023

Do you need planning permission for a loft conversion?

Kimberley Taylor
Writer & Researcher

Table of contents

  1. 1. What is planning permission?
  2. 2. Do you need planning permission for a loft conversion?
  3. 3. Permitted Development Rights
  4. 4. Permitted development rules for a loft conversion
  5. 5. Location limitations
  6. 6. Planning permission for a loft conversion
  7. 7. How much does planning permission cost?
  8. 8. Types of loft conversions
  9. 9. Summary: Your new living space is within reach!

If you're considering a new development project, it's really important to know what the rules and regulations are. Maybe you want to build a roof extension, add some roof windows to your attic room, create some sound insulation for a new (noise free!) playroom, or just build more storage space for your bits and bobs. A loft conversion is a really popular route for homeowners to take.

Loft conversions are a great way to add some personality to your home. Not only that, increasing your loft space has the potential to seriously rack up your property's value, which is great for future saleability.

Knowing your building rights is key to ensuring your new development project is all above board. Do you need building regulations approval? Have you considered fire safety? Is it a planning permitted development project, or do you need to make a planning application? Make sure you cover all the bases before going ahead with your new build.

What is planning permission?

Planning permission refers to the approval homeowners need for the extension, construction or demolition of a property.

Many homeowners who want to make structural changes to their home will need to make an application, though they don't always need planning permission for a loft conversion.

Do you need planning permission for a loft conversion?

In most areas of the UK you can design a loft conversion without planning permission, provided it meets permitted development rules. It's also highly recommended you apply for a Lawful Development Certificate from your local planning authority to double check your plans qualify.

Not only does this give you absolute certainty you don't need planning permission, but it's useful for any future mortgage lenders or prospective buyers who might want evidence in future.

Permitted Development Rights

Permitted development rights are a government scheme designed to enable more homeowners to expand their properties.

One of the biggest categories benefitting from this scheme is loft conversions. It meant in some cases, property owners wouldn't need full planning consent to go ahead with a loft conversion.

Permitted development rules for a loft conversion

If your loft conversion meets the following criteria, you're eligible for permitted development rights:

  • It uses similar building materials to the existing house.
  • The roof can't be higher than the existing house's highest current point.
  • Your loft extension or conversion mustn't exceed the volume allowance for permitted development. It mustn’t exceed 50 cubic metres of additional roof space for detached and semi-detached houses, and no more than 40 cubic metres for a terraced house.

When studying the permitted development rules, the original house refers to its state as it was built; any previous extensions from old owners will count toward your cubic metres.

Other criteria includes:

  • The development mustn't include a roof window in any wall or roof slope forming a side elevation of the dwelling house.
  • Any side facing windows must be obscure glazed or frosted, and any windows are non-opening if they're below 1.7 metres from the floor level.
  • The roof pitch of the main part of the conversion is the same as the roof pitch of the existing house.
  • The eaves have to be maintained.
  • The dormer wall is set back a minimum of 20 cm from the existing wall face.
  • You mustn't install, alter or replace chimneys, flues, soil and vent pipes.
  • The loft extension mustn't include any verandas, balconies or raised platforms.
  • The roof enlargement doesn't overhang the outer face of the wall of the original house.
  • Apart from hip to gable roof conversions, extensions must be set back at least 20 cm from the original eaves, as measured along the roof plane.

You'll also need to make sure permitted development rights are still valid in your area, otherwise you'll need to seek planning permission.

Adding a balcony to a loft conversion

A balcony is defined as a platform with a rail, balustrade or parapet that projects outside an upper story of a building. Usually, balconies need planning permission, but if it's a Juliet balcony (where there's no platform or and therefore no external access) this will fall under permitted development rights.

Conditions for the current house

Your current house will also need to meet certain conditions. It mustn't contain one or more flats, or be a contained flat within a building. The current house must also not have had any additional storeys added to it under permitted development rights.

The building must also not have been changed to be used as a house (when it was previously under non-residential use) under permitted development rights.

Location limitations

Areas of outstanding natural beauty may not allow permitted developments, including roof extensions and loft conversions. These areas include conservation areas, national parks, world heritage sites, listed buildings or other designated land where the local council has decided to formally withdraw permitted development rights.

If you're living in a national park or other protected area, it's always better to seek professional guidance if you're unsure about whether your area falls under this category.

It may be possible to apply for planning permission in a conservation area, so long as your planned development doesn't disrupt or ruin the existing environment. You'll need planning permission for a dormer loft conversion or roof extensions, and you must get the necessary consent before beginning any works.

Planning permission for a loft conversion

Though most loft conversions won't require planning permission, there may be some circumstances in which they do.

Flats or Maisonettes

If you're only carrying out internal works in your flat or maisonette, chances are you won't need planning permission. But if you're developing a roof extension or altering the dormer, planning permission is required.

How much does planning permission cost?

A loft conversion planning permission application is £234. You'll also need to think about other fees, such as planning consultant's advice, a possible structural survey, as well as design work and drawing production.

If you're using the permitted development route, you'll need to pay for a Lawful Development Certificate application which costs £128.

As we've mentioned before, it's always better to obtain a Lawful Development Certificate because it proves to your local authority and any future buyers that your development project was legal at the point of construction. This legally protects you if any permitted development rules change, and also avoids any risk of fines or demolition down the line.

Types of loft conversions

If you want to convert your loft into a usable room, you'll need building regulations approval even if you don't need planning permission. But whether you require planning permission or not will depend on the type of loft conversion and the shape of your roof.

Roof light loft conversion

A roof light loft conversion or room in loft conversion refers to when you don't alter to expand the roof space, but you just add in windows and reinforce the floor to make it a more liveable space. These types of conversion will rarely need planning permission.

Dormer loft conversions

A flat roof dormer loft conversion is the most popular type of loft conversion. This is a structural extension that projects vertically from the existing roof slope to create a box shape. Because this type of loft conversion doesn't usually require any huge changes and permits the installation of windows, planning permission isn't usually needed.

Hip to gable loft conversion

Becoming increasingly popular to homeowners, a hip to gable loft conversion is often good for end of terraced houses and detached homes. This type of loft conversion straightens an inwardly slanted end roof to create a vertical wall. You might need planning permission for a loft conversion if it's hip to gable.

Mansard loft conversion

Mansard loft conversions involve raising the side walls of your house and the ridge height of the roof. It changes the angle of the roof planes so they're much steeper at the sides and have a flat top section.

They're usually found at the back of a house and though they can be suitable for detached and semi detached houses, they're usually used in terraced houses. A mansard loft extension or conversion will nearly always require planning permission.

Summary: Your new living space is within reach!

Though there are some circumstances where you'll need to fill out a planning application, most loft extensions, conversions or other adjustments to attic space are considered permitted development projects. This means no planning application needed!

Of course, there are still building regulations to consider whenever you're making significant changes to a property, and it's always better to seek expert advice if you're unsure about anything. Make sure you know all your planning permission regulations before building to avoid breaching planning rules, otherwise you could end up with some hefty fines, or even the demolition of your project.

If you're exploring loft conversions or roof extensions to add value to your property, it's always good to know the number you're starting with. You can get an instant property valuation using our Online Valuation Tool. It's a great first step to get the ball rolling!

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