Garden Room Planning Permission

Installing a garden room can be a fantastic way to add extra space....

Installing a garden room can be a fantastic way to add extra space to your home without the disruption or cost of a full extension. Many people are looking for an extended living space – whether that be somewhere to work, to chill out, to work out, to entertain, to indulge in a hobby or even to house adult children or elderly parents.

Taking on a building project of any size can often seem somewhat daunting – particularly when it comes to planning permission.  This guide explains the planning rules for garden rooms in the UK in a clear and simple way, helping you understand when you need permission, when you don’t, and what your options are.

Before we dive into the details, it is worth noting that planning regulations do change from time to time, so the information in this guide is correct as at August 2025.  Please feel free to get in touch for any latest updates.

Do I Need Planning Permission for a Garden Room?

In many cases, no – garden rooms can fall under Permitted Development (PD) rights, meaning you don’t need to apply for full planning permission. PD rights are a set of national rules that allow homeowners to carry out certain building works – including the construction of outbuildings like garden rooms – without needing planning permission.

There are various criteria that such works need to meet in order to qualify for PD rights:

General Permitted Development Rules:

• Not used for sleeping accommodation (no bedrooms).
• Single-storey structures only.
• No verandas, balconies or raised platforms where they are over 300mm above ground level. This is to avoid any overlooking/privacy issues with neighbours.
• Must be for incidental use (e.g. home office, gym, studio and so on).

What Size Garden Room without Planning Permission?

Size and Height Limits:

• Maximum eaves height: 2.5 metres
• Maximum overall height:
  • 4 metres with a dual-pitched roof
  • 3 metres with a flat or single-pitched roof

• If within 2 metres of a boundary: maximum height is 2.5 metres
• Must not cover more than 50% of the “curtilage” – i.e. all outdoor space, so includes front and back garden, plus any area to the sides of the property, (including any existing outbuildings).  This excludes the house itself
• Internal size of the garden room must be no larger than 30 square metres – even if it falls within the 50% of the area rule.

Location Rules:

• Cannot be built forward of the principal elevation (i.e. not in front of the house)
• If in a conservation area, National Park, or AONB (Area of Natural Beauty), more restrictions apply (see below).

Special Cases: Conservation Areas, Listed Buildings, and Article 4 Directions

In designated areas (like conservation areas or if your home is listed), PD rights may be restricted or removed by the council. This is known as an Article 4 Direction. If your home falls under this, you will likely need to apply for planning permission even for small garden rooms.

Key tip: Always check with your Local Planning Authority if you live in a special area.

Certificate of Lawfulness (COL)

Even if your garden room falls outside of Permitted Development, you do not necessarily need to go down the route of requiring full planning permission.  Very often, applying for a Certificate of Lawfulness (also sometimes known as a Lawful Development Certificate, LDC) will suffice. This is a legal document issued by your local planning authority confirming that a proposed or existing development is lawful — meaning it does not require planning permission.

Benefits of a COL:

• Much quicker, simpler and cheaper process than full planning permission
• Peace of mind
• Prevents disputes with neighbours or enforcement
• Proof for buyers, mortgage lenders, or solicitors that the development is legal.  This can speed up the process of a property sale in the future, as well as removing potential extra costs at that point.
• Protects you from future enforcement action if you’re relying on Permitted Development rights.

The process to apply for a COL usually includes the following steps:

• You apply through your local council’s planning portal.
• As part of the application you need to submit:
  • Site plan & location plan
  • Elevation drawings
  • A description of the works
• There is a small fee to pay of around £103 for a proposed development.
• The council issues the certificate if the proposal complies with PD rules
• This process usually takes around 8-12 weeks

As with all other areas regarding planning permission, Urban Spaces will be happy to guide you and submit a COL application on your behalf.

When You DO Need Full Planning Permission

You’ll need to submit a full planning application if:

• The garden room doesn’t meet PD rules (e.g. too tall, too large, too close to boundaries)
• It will be used as self-contained living accommodation (an annexe)
• You’re in a conservation area with an Article 4 Direction
• Your property is listed or on designated land

Planning applications can currently take several months and local authority fees typically cost around £206 (2025 rates). Your council will assess the visual impact, privacy concerns, and how the garden room fits with the area.  Any architects’ fees are not included in this – again we highly recommend speaking to us on this as we can produce the required architectural drawings on your behalf at a fraction of the usual cost.

Your Local Planning Authority

It is important to note that the guidelines documented here can vary depending on where you live, as each local council or planning authority may have different rules on the criteria that apply.  Some councils take a much stricter approach than others so please do get in touch with us so we can advise further.  Having been through this process multiple times, we do have a very successful track record in helping our clients secure all the necessary permissions for their garden room.

What About the Caravan Act?

The Caravan Sites and Control of Development Act 1960 and the Caravan Sites Act 1968 define a caravan as a moveable structure used for human habitation. Under certain conditions, a garden room could be classed as a caravan, especially if it:

• Is built off-site and delivered in one or two parts
• Is not fixed permanently to the ground
• Is used as living accommodation (e.g. annexe)

If your garden room meets this definition and is within your garden, it may be exempt from planning as long as it remains ancillary to the main house (e.g. not rented out).

Note: Even if it meets the Caravan Act, you may still need permission in conservation areas or if Article 4 applies.

How Garden Rooms Can Avoid Planning Permission

So, in summary, to keep your build under PD and avoid needing full planning, the following conditions apply:

• Keep the height under 2.5m if close to a boundary
• Don’t use it as a bedroom or holiday let
• Use non-permanent foundations (like ground screws or pads)
• Ensure it’s for personal use only (e.g. office, gym, studio)
• Keep it within the 50% garden coverage limit

Here’s a quick checklist on the key criteria:

Question	If “Yes” = Planning Likely Required
Will it be used as living/sleeping space?	❌ Yes
Is it higher than 2.5m near a boundary?	❌ Yes
Is your property in a conservation area or listed?	❌ Possibly
Are you in an Article 4 area?	❌ Possibly
Is the building forward of the front wall of the house?	❌ Yes
Will it take up more than 50% of your garden?	❌ Yes
Will it have raised decking over 300mm?	❌ Yes

 

If you answered No to all, you’re likely within PD rights.  If you are looking for a larger garden room (above 30 square metres) then you may still not need full planning permission and a Certificate of Lawfulness will suffice.

Final Thoughts

Garden rooms are one of the most flexible, valuable additions you can make to your home – but only if you stay within the rules. At Urban Spaces we help homeowners across the UK design garden rooms that are fully compliant, stylish, and stress-free.

If you’re unsure whether you need planning or want help applying for a Certificate of Lawfulness, we’re here to help.

Need advice? Contact us today for a free consultation.