Bespoke Garden Annexes for Independent Living
Planning permission is one of the most common questions families ask us before starting a project — and with good reason. Planning rules for granny annexes in the UK can seem complicated at first, but the process is often more straightforward than you might expect.
The short answer is that not every granny annexe requires full planning permission. Depending on the design, size, location and intended use, an annexe may qualify for an alternative planning route, such as a Certificate of Lawful Development or the Caravan Act 1968.
Most importantly, The Green Room can handle the planning process on your behalf, from assessing the most appropriate route through to preparing and submitting the relevant application — so you don’t need to become a planning expert.
This guide explains everything you need to know.
There are two main routes we consider for a self-contained granny annexe: the Caravan Act/Lawful Development route and Full Planning Permission. The most appropriate option depends on the size, construction, location and intended use of your annexe.
A granny annexe may not require full planning permission where the structure meets the statutory definition of a caravan and its siting and use remain lawful and ancillary to the main house.
Where appropriate, a Lawful Development Certificate (LDC) can provide formal confirmation from the local planning authority that the proposed siting and use are lawful.
Where an annexe falls outside the statutory caravan definition, exceeds the permitted dimensions or the circumstances of the site or proposed use require planning permission, we can follow the full planning application route instead.
This allows the local planning authority to assess matters such as the annexe’s size, design, location and impact on the surrounding area.
What is commonly referred to as the “Caravan Act route” comes from the legal definition of a caravan contained in the Caravan Sites and Control of Development Act 1960, as extended by the Caravan Sites Act 1968.
A qualifying structure can provide fully self-contained residential accommodation while still meeting the legal definition of a caravan.
However, meeting the caravan definition does not, by itself, grant planning permission. The location and use of the annexe are equally important when establishing whether it can lawfully remain within the garden of the main house without full planning permission.
For a qualifying twin-unit caravan, the assembled structure must not exceed:
In addition, the structure must consist of no more than two sections, separately constructed and designed to assemble on site using bolts, clamps or similar fixings.
Once assembled, it must remain physically capable of being moved from one place to another, whether by towing or transportation on a suitable vehicle.
Not necessarily.
The important test is whether the assembled structure remains physically capable of being moved.
Therefore, a high-quality residential annexe does not have to look like a traditional touring caravan. Modern modular construction can create a comfortable, highly insulated and fully fitted home while still meeting the statutory caravan definition where the design satisfies all the necessary criteria.
Not necessarily.
Where a qualifying caravan sits within the residential curtilage of a house and its use remains genuinely ancillary to the main dwelling, full planning permission may not be required.
However, we recommend establishing the planning position before installation. Where appropriate, this can involve applying for a Certificate of Lawful Development to obtain formal confirmation from the local planning authority.
Importantly, a Lawful Development Certificate is not planning permission. Instead, it provides formal confirmation that the proposed development or use is lawful for planning purposes.
In simple terms, the granny annexe should form part of the use of the main family home rather than operate as a completely separate dwelling.
For example, a granny annexe occupied by a parent or another family member can still provide its own bedroom, kitchen, bathroom and living space while remaining closely associated with the main household.
The exact circumstances matter, so we assess how you intend to use the annexe as part of determining the most appropriate planning route.
You should not assume that an annexe approved on the basis of ancillary residential use can later operate as an independent rental property.
Using the annexe as a separate dwelling could represent a material change in its planning use and may require a separate planning application.
Therefore, if rental use forms part of your plans, it is important to discuss this at the beginning of the project.
Full planning permission may provide the appropriate route where:
We assess these factors before recommending the most suitable route for your project.
Neither route is necessarily better. Instead, the right choice depends on your garden, requirements, annexe design and intended use.
This route may suit annexes that:
Where appropriate, obtaining a Lawful Development Certificate can provide valuable formal confirmation of the planning position.
This route may suit:
Full planning permission can also provide greater design freedom where reducing the size of an annexe simply to meet the caravan dimensions would compromise the layout.
A garden room, office or other incidental outbuilding may fall within permitted development rights if it meets all the relevant requirements.
However, sleeping accommodation changes the considerations, particularly where a building includes facilities such as an en-suite bathroom or is specifically designed for overnight accommodation.
For this reason, we recommend checking the planning and Building Regulations position rather than assuming a garden guest room automatically qualifies under permitted development.
Not automatically.
The planning status of an annexe and its VAT treatment are separate issues. Simply meeting the statutory definition of a caravan does not automatically make every annexe zero-rated for VAT.
The applicable VAT treatment depends on factors including the dimensions, construction and relevant residential standards of the particular unit.
Therefore, we assess VAT according to the individual project and apply it where applicable, rather than assuming every Caravan Act annexe automatically qualifies for zero VAT.
Sometimes.
If your original design sits close to the 6.8 metre width or 20 metre length limit, for example, we can explore whether adjusting the layout would allow it to meet the statutory caravan dimensions.
Alternatively, if you would prefer a larger annexe, full planning permission may give you greater freedom to create the layout you want.
The best approach is to establish this at the design stage, before committing to a particular planning route.
Read our complete guide to the caravan act.
We always recommend applying for a Lawful Development Certificate (LDC) from your local council, even when planning permission isn’t required. An LDC is a formal written confirmation from your council that your annexe is lawful. It protects you in the event of any future dispute — for example, when you come to sell your home. The Green Room manages this application on your behalf as part of our service.
Permitted development should not be confused with the Caravan Act or Lawful Development Certificate route.
Permitted development rights can allow certain garden outbuildings without a full planning application, provided they meet specific conditions. However, these rights apply to buildings used for purposes incidental to the enjoyment of the dwellinghouse and do not provide a general route for creating separate, self-contained living accommodation.
Therefore, we would not normally describe permitted development as the standard route for a fully self-contained granny annexe with a kitchen, bathroom, bedroom and living space.
Our two-bedroom granny annexe in Maidstone measures approximately 7 metres at its widest point.
Under the statutory definition applying to twin-unit caravans, the assembled structure must not exceed 6.8 metres in width.
As the Maidstone annexe exceeded this limit, it could not qualify under the twin-unit caravan definition. Therefore, we designed the project as a permanent garden annexe and successfully followed the full planning permission route.
This allowed the customer to have the larger layout they wanted without compromising the design simply to remain within the Caravan Act dimensions.
Every garden and every family are different. Consequently, there isn’t a single planning route that works for every granny annexe.
At The Green Room, we consider your available space, required layout, intended use and the construction of the annexe before recommending the most appropriate route.
Whether your project proceeds through a Lawful Development Certificate or full planning permission, our aim is the same: to create a high-quality, legally compliant granny annexe that meets your family’s needs now and in the future.
If you’re considering a one-bedroom, two-bedroom or larger granny annexe, speak to The Green Room about your garden and requirements. We can assess the project, discuss the available planning options and design an annexe around the space you have available.
Regardless of which planning route applies, all our granny annexes comply with Building Regulations. This covers structural safety, insulation standards, fire safety, electrical installation, plumbing and drainage, ventilation, and energy efficiency.
Every Green Room annexe is designed and built to fully comply with current Building Regulations as standard.
A self-contained granny annexe may have its own Council Tax band. However, depending on who lives in the annexe and how it is used, a 50% discount or full exemption may apply.
Read our granny annexe Council Tax guide to learn how banding, discounts and exemptions work.
Planning can feel daunting, but you don’t have to navigate it alone. For every project we undertake, The Green Room will:
– Confirm which planning route applies to your property
– Manage the Lawful Development Certificate application on your behalf
– Handle full planning applications where required, working with specialist consultants
– Ensure your annexe is designed and built to comply with all Building Regulations
– Provide all documentation you need for your records
Our customers rarely need to deal directly with their council at all.
We install granny annexes across the UK and provide a complete service, from initial design and planning through to manufacture and installation..
Explore our range of granny annexes to find out more about our designs, specifications and services.
Book your free site survey or get in touch today to begin your project the easy way.
Council Tax will depend on how the granny annexe is used and who lives in it.
A granny annexe may qualify for a full Council Tax exemption if it is the sole or main home of a dependant relative who meets the qualifying criteria. In some other circumstances, a Council Tax discount may be available.
As the position depends on the individual circumstances, we recommend checking with your local council to confirm whether an exemption or discount applies.
Read our granny annexe Council Tax guide for a full explanation of the current rules.
A Lawful Development Certificate (LDC) provides formal confirmation from your local council that the proposed use or development is lawful. Although an LDC is not always a legal requirement, we strongly recommend obtaining one before installing your annexe.
It provides clear evidence of the annexe’s lawful status, which can also be useful if you sell your property in the future. We manage the LDC application and council correspondence on your behalf.
A Caravan Act annexe is intended to remain ancillary to the main house, rather than operate as a separate, independent dwelling. Using it as a separate rental property or holiday let could change its planning status and may require further planning approval.
If you are considering renting out an annexe, you should check the proposed use with your local planning authority before proceeding.
Being in a conservation area does not necessarily prevent you from having a garden annexe, but additional planning considerations may apply. The appropriate route will depend on the annexe, its proposed use and the individual property.
We assess these factors as part of the planning process and can advise on the most suitable route for your project.
Not automatically. Meeting the Caravan Act requirements does not by itself mean that a garden annexe or lodge qualifies for zero-rated VAT. HMRC applies separate VAT rules, including conditions relating to the size and construction of the building.
Some items and parts of the project may also have different VAT treatment. We assess each project individually and clearly show any applicable VAT within your quotation.
For more information, see the Government guidance on VAT treatment of caravans and houseboats.
Some granny annexes are designed to meet the legal definition of a caravan under the Caravan Act, which means they must be capable of being moved. However, relocating an annexe is a specialist operation that would usually require professional lifting equipment and transport.
In practice, most homeowners install their granny annexe as a long-term addition to their property.
If an annexe does not meet the relevant Caravan Act requirements, a different planning route may apply, which can include full planning permission. We assess this at the start of your project and advise on the appropriate route for your proposed annexe.
Not every granny annexe requires full planning permission. Depending on the design, siting and intended use, your project may require a full planning application or it may be appropriate to obtain a Lawful Development Certificate (LDC).
Where a granny annexe meets the relevant Caravan Act requirements and is used in connection with the main house, full planning permission may not be required. However, we recommend obtaining an LDC to formally confirm that the proposed use is lawful.
We’ll assess the appropriate planning route for your project and manage the application and local authority correspondence on your behalf.
For more information, see our granny annexe planning guide.
Still unsure which planning route applies to your property? Our team surveys hundreds of sites every year across the UK and can give you a clear, honest answer within minutes.
Book your free site survey today — we’ll handle the planning so you don’t have to.
If the local planning authority is satisfied that the appropriate legal tests have been met, it will grant a lawful development certificate. Read more on https://www.gov.uk/guidance/lawful-development-certificates
A Lawful Development Certificate (LDC) is a legal document stating the lawfulness of past, present or future building use, operations, or other matters. For technical information https://www.planningportal.co.uk/planning/planning-applications/consent-types/lawful-development-certificate
This article on The Home Owner Alliance website is an interesting read. The expense of later life care, increasing property prices, and the fact grown children are coming home (or never leaving), have all contributed to the rise in “granny” annexes in recent years.
Our team of down-to-earth experts genuinely care about great garden spaces and excellent customer service. Whether you’re just starting to explore your options or ready to move forward with your project, we’re here to help.