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Planning Permission Loft Conversion

Do you need planning permission for a loft conversion?

By Heather · 12 May '22  · 

3 min read


Short answer: maybe.

Loft conversions come in all sorts of shapes and sizes, and whether or not you need planning permission will depend on these factors:

  • The type of loft conversion
  • The size
  • What type of house you live in
  • Where you live in the UK

To help you navigate these planning hoops, our planning team have prepared this helpful guide…

Permitted Development Rights

A Government scheme designed to get more homeowners expanding their properties, permitted development rights let some loft conversions go ahead without the need for planning permission.

In order to quality, your conversion must fit within these guidelines…

  • A volume allowance of 50 cubic metres additional roof space for detached and semi-detached houses
  • Uses similar building materials to the existing house
  • The development must not include a window in any wall or roof slope forming a side elevation of the dwelling house
  • The roof pitch of the principal part of the dwelling must be the same as the roof pitch of the existing house
  • A dormer wall that is set back at least 20cm from the existing wall face
  • Has windows that are non-opening if less than 1.7m from the floor level
  • Has side windows that are obscured/frosted

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It’s worth noting, these allowances include anything added to the original house ("original" being the latest of when the property was built or if it was built before 1948, then as it stood on 1st July 1948). So if your loft has already been extended by a previous occupant that counts towards your cubic metres.

Naturally, these rules can be quite confusing, especially if this is your first conversion. To make sure things run smoothly, we recommend getting an architect by your side, to make sure your permitted development rights are used… well, right.

Lawful Development Certificate

If you do opt to use your permitted development rights, we highly recommend obtaining a lawful development certificate.

It essentially proves to both your local authority and future buyers that your home project was legal at the point of construction. This protects you in the event the rules around permitted development right change, and ensures all the guidelines have been met.

If your project is found to be in violation of the rules, you can face both some hefty fines, and even the prospect of demolishing your conversion. Risks no homeowner should be taking!

Homes that need planning permission

While permitted development rights are great, they don’t apply to all house types.

  • Flats
  • Maisonettes
  • Listed buildings
  • Homes in conservation areas

These homes are all excluded from the scheme, and will require planning permission.

Types of loft conversions

When it comes to expanding your loft space, there are three traditional options homeowners often go for - each with its own planning considerations.

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Two Storey

Roof light loft conversion

A roof light or room in loft conversion is where you don’t alter or expand the existing space at all, but simply add in windows and reinforce the floor to transform an attic into a comfortable living space.

Rarely needs planning permission.

Dormer loft conversion

The most popular type of loft conversion is a simple flat roof dormer. This is a structural extension which projects vertically from the slope of the existing roof, creating a box shape. This loft extension generally requires no dramatic changes, and allows for the installation of conventional windows.

Planning permission is often not required.

Hip to gable loft conversion

Ideal for end of terrace and detached homes, a hip to gable loft conversion straightens an inwardly slanted end roof to create a vertical wall. This small change can make a huge difference to the feel of the living space inside, and is becoming an increasingly popular option for homeowners.

Planning permission might be needed.

Mansard loft conversion

Constructed by raising the party wall (the wall shared with your neighbours). The roof remains flat, while one outer wall slopes gently inwards. Mansards are typically found at the rear of the house, and although they are suitable for many property types, they are most popular in terraced houses.

Often requires planning permission.

How Resi can help...

Are you ready to begin your home transformation journey? Then this is the place to start.

Through our online Dashboard, we’ll guide you through each step of the process, as your designer packages up your ideas into a set of architectural drawings. We’ll then pass you over to our planning team, who will act as your agent, and give you the best chance of first time approval.

At Resi, we’ve helped over 1000 homeowners secure planning approval. Whether through a full planning application, or by using your permitted development rights, we’ve got all the expertise you’ll need!

Discover your home’s potential by book in a free consultation with our team.

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