A garden caravan appeal has succeeded in Isleworth after a Planning Inspector accepted that a proposed mobile home could be moved as a single unit and would remain part of the household’s existing residential use. Hounslow Council had refused a certificate of lawful proposed use, but the Inspector found that planning permission was not needed for the particular arrangement described.
Inspector Siobhán Watson issued her decision on 30 October 2026 in appeal APP/F5540/X/25/3365649. The proposal concerned a mobile home in a rear garden at Eve Road, to be occupied by a close family member. The ruling is about the legal status of the proposed structure and its use, not whether the Inspector thought the building looked attractive.
The garden caravan appeal is especially useful alongside an Ealing decision published the previous week, where a similar claim failed because the applicant could not establish how the completed structure could be lifted intact. Together, the cases show why technical evidence and the household’s actual relationship with the accommodation both matter.
Why the garden caravan appeal succeeded
The appeal followed the refusal of application P/2025/0644, submitted on 3 March 2025 and refused by Hounslow on 28 April. The applicant, Sylwia Kopica of Your Extra Space Limited, sought a certificate under section 192 of the Town and Country Planning Act 1990. An application of this kind asks whether the development described would be lawful, rather than asking the council to grant discretionary planning permission.
Two legal questions controlled the outcome. First, would the completed mobile home qualify as a caravan, or would its construction amount to building operations? Secondly, would occupation by a family member create a separate residential planning unit, meaning a material change in the use of the garden? The Inspector answered both questions in the appellant’s favour, on the evidence provided.
The caravan had to be physically movable
The proposed unit measured 11 metres long and 3.6 metres wide, with an internal height of 2.4 metres. Its dimensions were not disputed. It was to be assembled on site around a steel frame, incorporating lifting points, and supported on ground screws by its own weight rather than permanently anchored to them. Services were designed to be disconnected.
Crucially, the appellant supplied technical information about lifting the assembled structure by crane onto a suitable lorry. In this garden caravan appeal, that was stronger evidence than a bare assertion that the structure was designed to move. The question was whether the whole completed unit had the physical characteristics needed for transport, not whether the owner was actually planning to relocate it.
Hounslow argued that the surrounding road was too narrow to move the unit away once assembled. The Inspector rejected that objection to its caravan status. She explained that “a lack of intention to move is not relevant”, and neither was the absence of a suitable route or access for a transport vehicle. This is an extract from the official Planning Inspectorate decision, reproduced under the Open Government Licence.
The important distinction is between a structure capable of being moved as a whole and the practical inconvenience of doing so. The caravan definition in section 29 of the Caravan Sites and Control of Development Act 1960, together with the 1968 Act, focuses on the structure’s characteristics. This was not a finding that any object described as a mobile home necessarily qualifies.
Why the family arrangement remained one dwelling
The second issue was the proposed use. The mobile home would contain normal living facilities, but would have no separate postal address, letterbox, entrance, utility meters or private garden. Its intended occupier was a close family member living in association with the main house. The Inspector regarded those characteristics as pointing to one continuing residential planning unit, not the creation of a second self-contained home.
That finding is central to the garden caravan appeal. A relative sleeping or living in an annexe does not automatically create a new dwelling, even where the accommodation includes facilities for day-to-day living. The relevant question is whether the arrangement remains part and parcel of one household, viewed as a matter of fact and degree. A physically separate unit occupied independently by a different household can present a very different planning position.
Readers considering similar arrangements should distinguish a caravan used as an annexe in a domestic garden from a separate residential letting. Living accommodation is not normally an incidental use in the same sense as garden storage or hobbies. It can instead be ancillary to the existing dwelling because it remains within the same overall residential use. That difference matters when identifying the relevant legal route.
The court decisions behind the caravan test
In considering whether the structure would be a building, Inspector Watson referred to Cardiff Rating Authority v Guest Keen Baldwin and the Court of Appeal decision in Skerritts of Nottingham. The familiar factors are size, permanence and physical attachment, considered together. Neither the overall dimensions nor the absence of conventional foundations determines the answer on its own.
The garden caravan appeal does not abolish those tests. The unit’s frame, support, lifting capacity and lack of fixed anchoring mattered because they demonstrated that this particular proposal was a movable structure rather than a permanent building. Our existing guide, is a caravan a building?, explains why a structure’s label or commercial description does not settle its status in planning law.
The more difficult question often concerns the evidence. Engineers’ drawings, connections, lifting points, structural information and a credible means of loading may be material where a council doubts that a structure can survive movement. The relevant test should be applied to the completed unit, rather than to components before assembly. The Inspector considered the information sufficient in this case.
A different result from the Ealing mobile home appeal
On 22 October 2026 a separate garden mobile home appeal in Ealing was dismissed. There, the proposed two-section structure lacked adequate evidence that the completed assembly could be lifted and transported without damage. The Inspector also found that the Class E outbuilding right could not authorise the scheme, both because of its height near boundaries and because the use was primary living accommodation rather than incidental to the dwelling.
Comparing the two decisions makes the successful Isleworth garden caravan appeal more informative. A mobile home can be too poorly evidenced to qualify as a caravan even where its dimensions are acceptable. Conversely, proof of mobility does not alone settle whether the proposed occupation creates an independent dwelling. Applicants need to demonstrate the structure’s status and the character of the proposed use as two separate questions.
A certificate is not blanket permission for future uses
The certificate granted on appeal identifies the siting of a caravan in the rear garden for occupation by a family member as part and parcel of the main C3 dwelling. It relates to the precise scheme and relevant date considered. It does not authorise a different construction method, permanent foundations, independent residential letting or a new planning unit that the Inspector never assessed.
The garden caravan appeal is also different from an enforcement appeal resolved on planning merits. In another Hounslow decision issued the same day, appeal APP/F5540/C/25/3360814, Inspector Watson rejected an immunity argument for a separately occupied garden outbuilding because the occupation evidence conflicted, but nevertheless allowed the ground (a) appeal and granted permission after finding the use acceptable on its merits. That was a different legal route and a different site.
Anyone considering the certificate route can read our guide to caravan lawful development certificates. The most useful approach is to specify exactly what will be built or stationed, who will use it, whether facilities and access are shared, and what evidence proves the relevant structure is movable. Trying to obtain a broad certificate with an incomplete description is likely to create uncertainty rather than resolve it.
Why this decision matters for garden accommodation
The result is encouraging for households seeking additional accommodation for a relative without creating a separate home. But it is a fact-specific certificate decision, not an exemption for all garden rooms or a general right to build detached residential accommodation. The same physical unit, used independently or built in a different way, might need planning permission.
For councils, the decision also shows why a narrow road or an apparent intention to keep a mobile home permanently in place does not by itself defeat the statutory caravan definition. The Inspector examined the structural evidence and the proposed use instead. For applicants, the practical lesson is to make that evidence clear at the outset, rather than relying on the words ‘mobile home’ in an application description.
The appeal decision and sources
Inspector Siobhán Watson allowed appeal APP/F5540/X/25/3365649 on 30 October 2026, overturning Hounslow’s refusal of the certificate application. The decision is also available on AppealBase. The separate Hounslow enforcement decision APP/F5540/C/25/3360814 is cited only as a contrast between a finding of lawfulness and a grant of planning permission on appeal.
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