If you’re considering adding a garden room or outdoor building in Cornwall, one of the first questions you’ll likely ask is whether planning permission is required. The good news is that in many cases, the answer is no – but it does depend on the size, height, and intended use of the building.
Understanding the rules around permitted development, mobile homes, and lawful use is essential before progressing with your project. At Garden Buildings Cornwall, we help customers design and install bespoke structures that comply with current regulations while still achieving the perfect space for their needs.
Do I need planning permission for a garden room in Cornwall?
In most cases, garden rooms fall under what is known as permitted development rights. This means you can build without applying for full planning permission, provided certain conditions are met.
Typically, a garden building will qualify if:
- The total footprint is under around 30m²
- The structure is single-storey
- The maximum height is generally 2.5 metres
- If placed more than 2 metres from the boundary, the height may increase to:
- Up to 3 metres for a flat or pent roof
- Up to 4 metres for a pitched or apex roof
- Up to 3 metres for a flat or pent roof
- It is used as an ancillary space (such as a home office, gym, studio, or hobby room)
These guidelines make it possible for many homeowners to create highly functional outdoor spaces without the delays and costs of a planning application.
However, the key factor is always use. As long as the building is not used as a separate living accommodation, it will usually remain within permitted development rules.
When a Garden Room Becomes a Home
The situation changes when a garden building is used for sleeping accommodation or self-contained living.
If the structure includes sleeping space, a bathroom, kitchen, and operates independently from the main house, it may be classed as a new dwelling. In these cases, planning permission is often required.
This is where many homeowners become interested in alternatives such as garden lodges or mobile homes, which can sometimes offer more flexibility under different regulations.
At Garden Buildings Cornwall, our bespoke timber frame mobile homes are built to comply with the 1968 Caravan Act and BS3632 Park Home Regulations. This distinction is important, as it can significantly influence whether planning permission is required.
Do I need planning permission for a mobile home in Cornwall?
In Cornwall, many garden buildings do not need full planning permission if they fall under permitted development rules. However, if you want certainty, you can apply for a Lawful Development Certificate (LDC) through Cornwall Council. This confirms your building is legal and helps avoid any future planning issues.
Despite the name, mobile homes and lodges that fall under 1968 Caravan Act do not need wheels, but they must be transportable and meet specific size limits (typically up to 20m x 6.8m).
To qualify under caravan rules, the building must:
- Be within the garden of the main house
- Be used as ancillary accommodation for family or guests
- Be built in a way that allows it to be transported in sections
- Not be a separate rental or independent dwelling
- Not change the use of the land
If these conditions are met, planning permission is often not required – but it is always best to confirm with Cornwall Council, or apply for an LDC for added reassurance.
Planning Advice and Peace of Mind
While many garden buildings fall under permitted development or caravan legislation, every site is slightly different. Factors such as location, land designation, and intended use can all influence whether permission is required.
That’s why we always recommend speaking with Cornwall Council early in the process. In many cases, applying for a Lawful Development Certificate is the simplest way to confirm everything is compliant before construction begins.
Ready to Plan Your Garden Room, Lodge or Mobile Home in Cornwall?
If you’re considering a garden room, lodge, or mobile home in Cornwall, the first step is understanding what you can build on your site and whether it falls under permitted development or requires planning permission.
At Garden Buildings Cornwall, we are a family-run business based at Goonhavern Garden Centre, specialising in bespoke timber frame garden buildings, lodges, and mobile homes.
From design to installation, we work with you to create a space that suits your lifestyle, budget, and long-term needs.
Get in touch with Garden Buildings Cornwall today to discuss your ideas, explore designs, and find out whether your project falls under permitted development or requires planning permission.
We’ll help you make the process simple, clear, and stress-free – so you can focus on creating your perfect space.
Please note: Planning regulations are subject to change, and guidance should always be confirmed with Cornwall Council or a qualified planning advisor before proceeding.