Your Complete Guide to Planning Rules, Exceptions and Support

Not sure if your garden room project needs planning permission? You're not alone. It’s one of the most common questions homeowners ask us – right after “How big can I go without it?”

At Luna Spaces, we’ll tell you quickly and clearly if planning applies to you and what steps are needed. For most of our builds, the answer is simple: no, you don't need it. But for some, it’s essential.

We’re here to guide you through every step so there are no surprises before, during or after your build.

What is Planning Permission?

Planning permission is formal approval from your local planning authority to build something that changes how a property or plot is used or looks. It ensures that your new structure fits local development plans and does not negatively affect the surrounding area.

While most small, detached garden rooms fall under Permitted Development Rights, there are important exceptions based on size, placement, use case, and location.

When You Do Not Need Planning Permission

Garden rooms are typically allowed under Permitted Development, which grants homeowners the right to build certain structures without applying for full planning.

Your garden room should qualify for Permitted Development if it:

• Is single storey and under 2.5 metres high (flat roof) from ground to eaves

• Has a pitched roof up to 4 metres high, but with eaves under 2.5 metres

• Is placed behind your home (not in front)

• Is not closer than 2 metres to any boundary (if over 2.5 metres high)

• Does not take up more than 50% of your garden area

• Is not used for overnight stays or as a separate home

• Complies with flood zone or heritage site guidelines if relevant

In these cases, you’re legally allowed to build without formal planning consent.

When Planning Permission Is Required

You will need planning approval if:

• You live in a conservation area, AONB, National Park or listed property

• Your structure is built in front of your house

• Your garden room is over 2.5m high and within 2m of a boundary

• You are creating a self-contained residential unit or anything with sleeping accommodation

• You propose decking or steps over 30cm in height

• Your total outbuildings exceed 50% of your plot (including sheds, garages, and other structures)

If any of these apply, we will advise you clearly and help guide or manage the application process on your behalf.

Not sure about your situation? Ask us. We will check your postcode and provide a straight answer.

What’s the Difference Between Planning and Building Regulations?

Planning PermissionBuilding RegulationsControls what can be built and whereControls how something is builtManaged by the Planning DepartmentManaged by Building ControlAssesses visual and environmental impactAssesses safety, structure and energy performanceMay not apply if within Permitted DevelopmentMay still apply depending on usage and plumbing

Learn more about Building Regulations here.

How We Help at Luna Spaces

We offer full support before, during and after the planning stage. Our approach includes:

1. Site Review and Design Guidance

We’ll check your layout, location and local restrictions to determine if permission is needed.

2. Permitted Development Checks

We confirm whether your build falls under national permitted development rules.

3. Planning Application Support

If needed, we prepare drawings, submit forms, and communicate with your Local Planning Authority. This includes:

• Planning portal applications

• Certificate of Lawfulness submissions

• Heritage statements (for conservation areas)

4. Trusted Partner Network

We have planning consultants and architects on hand to assist with more complex cases or full design and access statements if required.

Who Decides?

Planning outcomes are issued by your Local Planning Authority (LPA), usually within your Borough or District Council. Each one has slightly different policies and timeframes.

Most decisions take 8 weeks from submission to approval. We manage these timelines within your project planning to avoid delays.

Common Local Authorities We Work With

• Brighton & Hove City Council

• Lewes District Council

• Mid Sussex District Council

• Wealden District Council

• Arun District Council

• Tunbridge Wells Borough Council

• Guildford Borough Council

• Sevenoaks District Council

• Horsham District Council

We are familiar with their processes and can help navigate online systems such as the Planning Portal.

Real Examples from Luna Clients

• Home office near Hove: No planning required under Permitted Development

• Guest annexe with ensuite in Shoreham: Required planning due to sleeping space and tree preservation orders

• Garden bar and kitchen in Tunbridge Wells: Needed planning due to use and decking elevation

• Studio in a Lewes conservation area: Required full permission with design considerations

• Golf simulator room in Mid Sussex: Permitted as long as height and boundary rules were observed

Free Guidance? Yes

At Luna, we include planning checks as part of your consultation. You don’t need to worry whether it’s allowed or not — that’s our job.

If it needs submission, we’ll tell you upfront and take care of it professionally.

Start With Confidence

Planning decisions can affect timings, design and price. That’s why we include it at the start of every project — not halfway in.

Want to check your situation?
Reach out for a free design consultation and we’ll guide you clearly.

• Book your consultation

• Call us on 01273 020327

• Or email hello@lunaspaces.co.uk

Let’s make it simple, from design through to delivery.