The Caravan Act for Granny Annexes & Mobile Structures in Gardens

So, you may have heard that you can just put an annex in your garden using The Caravan Act, yes?

Well, first take a few minutes to familiarise yourself with what this means and then you can make an educated decision.

Spoiler - it's not that simple... 

Our team is often asked about the Caravan act use to allow a garden annex. Because there are so many different interpretations of planning laws by different councils across the country, it is important that:

1. You are fully aware of what the Caravan Act allows
   
   
2. If you decide to use this, that you properly back this up, by contacting your local council to get something in writing. 

Often, councils may still cast doubt and insist on some sort of planning application and this is why Blue Bee uses independent, experienced granny annex planning consultants.

If you need help with this:

Please ask and we can put you in touch with a independent specialist garden annexe planning consultant.

Definition of a ‘Caravan’ (Mobile Home):

An alternative route to create a granny annexe is to use a structure that meets the legal definition of a “caravan” or mobile home.

Under the Caravan Sites and Control of Development Act 1960 (as amended by the Caravan Sites Act 1968 and later regulations), a “caravan” is defined as

This definition includes not only traditional touring caravans, but also larger static caravans or mobile chalets – even if assembled on site – as long as they satisfy certain size and construction limits.

Specifically, a twin-unit mobile home can still count as a caravan if:

• (a) it is composed of no more than two sections that are assembled on site (e.g. delivered in halves and bolted together), and
  
  
• (b) once assembled, it is physically capable of being moved as a single unit by road.

There are maximum size dimensions:
in England, a caravan (mobile home) may be up to 20 metres in length, 6.8 metres in width, and with an internal ceiling height up to 3.05 metres.

Anything larger or constructed in more sections would not legally be a “caravan.” Importantly, a structure fixed permanently to foundations (like a brick building) is not a caravan – it must be a mobile unit, typically resting on its own frame or wheels, even if it’s skirted around the base for appearance.

If you need help with this:

Please ask and we can put you in touch with a independent specialist garden annexe planning consultant.

Why Caravans Matter for Planning:

Placing a caravan within the curtilage of your house for use ancillary to that house can be done without needing separate planning permission in many cases. The key distinction is between operational development (building work) and use of land.

1. A caravan is not a building; it’s a chattel (movable property).
   
   
2. So putting a caravan on your land isn’t building a structure, it’s changing the use of the land slightly.

Planning law generally allows the use of land within a home’s curtilage for purposes incidental to the dwelling without treating it as a separate “development,” as long as it remains part of the same planning unit.

In plain English: if the caravan is used only as extra accommodation for the people living in the main house (family members, etc.), with no separation in household, then “there would be no development taking place” in the eyes of the law – no material change of land use – and thus no planning permission required.

Provided the caravan is within the residential curtilage and used for ancillary residential purposes (not as an independent dwelling), “planning permission is not required” because it doesn’t create a new planning unit. The use is considered part of the normal use of the dwellinghouse.

Keep reading, though... it's not that simple...

The Caravan Act requires buildings to meet certain definitions

However, this scenario rests on the caravan meeting the legal definition and the use remaining ancillary.

If those conditions aren’t met, the council can argue a material change of use has occurred (for example, turning your garden into a separate dwelling site). Although a well-known appeal case established that using a mobile home as ancillary accommodation for relatives did not require planning permission since it did not amount to a separate planning unit (the family still functioned as one household), as noted below, you still need to check with your local council, and get proper confirmation in writing to cover yourself. But if you were to rent the caravan to a stranger or use it as an entirely independent residence, that would not be ancillary and would definitely need permission.

If you need help with this:

Please ask and we can put you in touch with a independent specialist garden annexe planning consultant.

Ancillary Use vs. Separate Dwelling:

Councils can be wary of caravan annexes because if the unit has all the facilities (kitchen, bathroom, etc.), it looks like a separate dwelling. The test is how it’s used in practice.

1. If it’s a family member who takes some meals in the main house, shares utility bills, and isn’t living “separately” in a broader sense, it can be ancillary.
   
   
2. To avoid doubt, some authorities say an ancillary mobile home should ideally rely on the main house for some facilities (for instance, not have a full kitchen) - but this isn’t a hard rule in law, just one way to reinforce the ancillary nature.

In fact, it’s possible for a fully self-contained mobile unit to be ancillary if occupied by dependent relatives as part of one household. The presence of a second front door or kitchen does not automatically create a new planning unit – it’s about the relationship and intention.

This is a grey area and often comes down to “fact and degree” on a case-by-case basis.

Practical Approach to The Carvan Act:

Many annexe suppliers build units to caravan specifications and advise using the Caravan Act route.

The typical process is: ensure your design falls within caravan size limits; site it within the curtilage (usually as close to the main house as reasonable); and use it for a family member.

However, it’s highly advisable to then apply for a Certificate of Lawfulness (LDC) for use of the land for an ancillary mobile home, to get the council’s formal sign-off that no permission is needed.

If the LDC is granted, you have permission in principle to station the caravan indefinitely as ancillary accommodation. If the council refuses the LDC (disagreeing on the facts or use), you might fall back to needing full planning permission after all.


Important: You are responsible for making sure that you follow all rules pertaining to your own property and the area you are in and that you obtain the relevant permissions. 

If you need help with this:

Please ask and we can put you in touch with a independent specialist garden annexe planning consultant.

Pros & Cons of Using the Caravan Act for a Granny Annexe

If you need help with this:

Please ask and we can put you in touch with a independent specialist garden annexe planning consultant.