Planning permission – everything you need to know

Whether you want to convert, extend or build new, make sure you have permission first

The planning process can be daunting, but the good news is that there are a number of projects that can be built under Permitted Development (PD), without needing to apply for planning permission. Going down the PD route saves time, money and hassle, while adding value to your home.

1. What are the easy ways to extend?

red brick wall house with bifold door and plants pot

(Image credit: Future PLC/ Veronica Rodriguez)

While PD does allow you to make changes to your home without obtaining planning permission, you are required to adhere to guidelines relating to size and appearance.

There are still procedures to follow and regulations differ between England, Scotland, Wales and Northern Ireland. Building Regulations need to be met and if you live in a conservation area, PD rights are likely to be more restricted, so check with your local authority.

There are also different requirements for listed buildings. Visit for full details of what’s allowed. In general, provided your property hasn’t been extended in the past, you can extend by fifty per cent of the total area of land around your house, but remember outbuildings and sheds count towards this percentage.

2. How to plan for ground-floor extensions

brown brick wall building grey bifold door dinning table and chairs in open

(Image credit: Future PLC/ Paul Raeside)

A rear extension is an obvious way to add space and will often turn a cramped kitchen into a spacious, open-plan living area. For single-storey extensions, you can build up to 3m from the back of an attached house and 4m from a detached house, and in England a temporary change to PD guidelines mean this has doubled to 6m and 8m respectively until 30 May 2019.

If you want to extend under the temporary changes, you’ll have to go through the free neighbour consultation scheme to gain prior approval.

Side extensions can only be single-storey up to 4m high and no more than half the width of the original house. Side returns might only add a few metres, but will transform an interior and have no impact on the size or layout of the garden. There are additional rules for ground-floor extensions regarding height, eaves and proximity to the boundary, which can also be found on the government’s planning portal.

3. What else can I build?

living room with blue wall white shelves pink sofa and wooden flooring

(Image credit: Future PLC/ Simon Whitmore)

Loft conversions are one of the most affordable additions. A local loft company will know what’s permissible under PD, but as a guide it must not exceed 40 cubic metres for a terraced house or 50 cubic metres for a detached or semi-detached house. This gives scope for rear dormers to make space for a bedroom and en suite.

Digging down and converting an existing cellar or basement into a living space is possible under PD. It’s an expensive and lengthy process, however, and you’ll need a specialist company to excavate and make it waterproof. Provided you don’t alter the footprint, garage conversions fall under PD, as does building a garden room as a home office, art studio or teenagers’ hangout.

To remain within PD, outbuildings should be no taller than 2.5m if they are within 2m of the garden boundary. Usage is a further issue: outbuildings built under PD can’t be used as self-contained accommodation, you’ll need planning permission for this.

4. What next?

dinning area with dinning table and chairs and flower pot on table

(Image credit: Future PLC/ David Merewether)

Apply for a Lawful Development Certificate, which proves work was permitted. If you decide to sell your property, buyers will want to see evidence that an extension or loft conversion was carried out legally.

5. How to get planning permission

roof space attic with white wall and wooden flooring

(Image credit: Future PLC/ David Giles)

For multi-storey projects or when the level of PD rights remaining on your property is not enough, you’ll need to apply for planning consent. It can take up to eight weeks for the planning office to consider an application and a fee is payable.

Loft conversions with a balcony or where the roof space needs to be altered, will also require permission, as will stand alone garage conversions and basements where a light well is added. Your local authority may also have a specific policy regulating construction that you have to comply with.

6. What is a party wall agreement?

If you’re building up to the boundary wall or excavating near one, you’ll need a Party Wall agreement as well as written consent from your neighbours. If they object, you’ll need to employ a surveyor to oversee the process. Find one via the Royal Institution of Chartered Surveyors (

Want more planning and extension advice? READ: Kitchen extensions – how to design, plan and cost your dream space

7. How to navigate the planning process

kitchen connected to gallery with glass door white and brown kitchen cabinet and white flooring

(Image credit: TBC)

Jude Tugman, co-founder of Architect Your Home, shares her advice for navigating the planning application process.

Invest in a professionally-produced plan

Planners always respond better to professionally-produced plans as they clearly show intentions and include all the relevant information.

How to deal with refusal

If your application is refused, you need to understand the reasoning behind it. If you only need to make a few minor changes, do so and then resubmit. But if the reasons are substantial, you can either rethink your plans or go to appeal.

What about building regulation?

As well as planning permission, you will also have to ensure your build adheres to Building Regulations.

Don’t forget part L

It is a Building Regulations requirement for the conservation of fuel and power to increase energy efficiency. As with most Building Regulations requirements they are generally based on good practice and your architect will know how to comply.

bedroom with white wooden wall white bed with designed cushion white drawer and white flooring

(Image credit: Future PLC/ Carolyn Barber)

Related: How to convert a garage – to make your room work for you

Are you in the process of applying for planning permission for your home extension project? We hope this handy guide helps you go about it the right way!

Deputy Editor

Jennifer is the Deputy Editor (Digital) for Homes & Gardens online. Prior to her current position, she completed various short courses a KLC Design School, and wrote across sister brands Ideal Home, LivingEtc, 25 Beautiful Homes, Country Homes & Interiors, and Style at Home.