Homeowners in Hillingdon are often taken by surprise when their application for an extension is suddenly refused. They thought their proposal to be small in size and similar to other extensions along the street, and had confidently assumed it would sail through.
Yet refusals are common. This is not always because an extension is unacceptable and should never be approved, but because of the way planning decisions are made in Hillingdon. The council has very strict local policies and the planners can be surprisingly reluctant to allow changes to individual houses.
A focus on design and character
Just Planning assesses hundreds of planning refusals in Hillingdon each year and, in our experience, most householder applications are refused on the basis of design and character. The council judges that the proposed extensions do not fit in with the local area. Most often it is about size – homeowners reasonably want extra space and the council is not keen to allow it.
Sometimes the council’s assessment can be frustratingly vague – officer reports describe proposals as being overly bulky, dominant or out of keeping with their surroundings, without clearly identifying what the practical harm would be.
In many cases, these judgements are finely balanced. Small differences in width, depth or roof form can make the difference between approval and refusal, even where the overall scale of development is relatively modest.
We have had a number of recent appeal successes in Hillingdon where the main issue was character. In this case in Uxbridge, we obtained permission at appeal for a new dwelling, for example, demonstrating to the inspector that the house would fit in well with the streetscene.
In the same week, we won an appeal for side and rear extensions to this house in Ickenham, where the council was mainly worried about harm to a conservation area.
The council’s Local Plan
When assessing planning applications for extensions, Hillingdon case officers start with their Local Plan policies. The key policy is DMHD 1, which sets out a list of requirements for domestic extensions.
It requires, for example, that ‘single storey rear extensions to detached houses with a plot width
of 5 metres or more should not exceed 4.0 metres in depth’ that ground floor extensions should be no more than 3 metres in height and that side extensions should be no wider than half the width of the main house.
The council’s policies are the starting point when it comes to assessing a proposal and it is obviously much easier to get permission if you comply with the policy requirements.
However, policies do not have to be followed in each and every case, as long as you have a clear justification. For example, you might argue that your side extension may be wider than half of the rest of the house on the basis that you are demolishing an existing garage in the same location that is wider than this limit.
The difficulty is that Hillingdon’s case officers are inclined to apply their policies quite rigidly, reluctant to make exceptions to their rules. IN such cases, it is often best to consider submitting an appeal.
Suburban spacing and the issue of subordination
Concerns about spacing between buildings and whether an extension appears subordinate to the original house are particularly common in Hillingdon. Side extensions, wrap-around extensions and proposals close to boundaries are frequently scrutinised on this basis.
What is often less clear from refusal decisions is how these judgements have been reached. Assertions that an extension would erode spacing or appear visually dominant are not always supported by a detailed explanation of the actual effect on the street scene.
At appeal, inspectors tend to examine these matters more closely, looking at the precise dimensions of the proposal, its relationship to the existing dwelling, and how it compares with the pattern of development that already exists in the area.
The impact on neighbouring properties
Impact on neighbouring properties is another frequent reason for refusal. In Hillingdon, this often relates to concerns about outlook, light or a sense of enclosure, particularly where houses are relatively close together.
While such impacts are relevant planning considerations, they need to be assessed objectively. The fact that a development would be noticeable, or that a neighbour objects to it, does not necessarily mean that it would cause material planning harm.
A common issue in refusals is that these impacts are described in general terms, without clear evidence that they would be unacceptable in planning terms.
Cumulative impact and previous extensions
Refusal decisions in Hillingdon often refer to the cumulative impact of extensions and alterations over time. Even where an individual proposal might appear acceptable in isolation, earlier additions to a property are sometimes relied upon to justify refusal.
This can be confusing for homeowners, particularly where previous works were permitted development or approved by the council. At appeal, however, inspectors will usually consider whether the cumulative effect of development genuinely results in harm, rather than relying on the existence of earlier alterations alone.
We recently won an appeal at Copthall Road East, in Ickenham, in which the council has refused planning permission for a single-storey rear extension, but they were mainly actually concerned about other extensions that had already been built at the house using permitted development rights.
Similar extensions nearby are not always decisive
A common frustration for applicants is the presence of similar extensions on the same street or in the immediate area. While these can be relevant, they are not automatically decisive.
The council may distinguish between developments approved under different circumstances or at different times, or may consider that earlier decisions no longer reflect its current approach. At appeal, the issue is usually whether those distinctions are meaningful when assessed objectively.
Simply pointing to neighbouring extensions is rarely sufficient on its own. What matters is how a proposal sits within the wider pattern of development and whether it causes planning harm in its own right.
Why an appeal can provide a more balanced review
Planning appeals are decided by the Planning Inspectorate rather than by the council that refused the application. Inspectors will consider the development plan and other material considerations, but they will also assess the actual effects of a proposal on its surroundings.
In cases where refusals rely on broad or generalised concerns, an appeal can provide an opportunity for those concerns to be tested more rigorously. Inspectors often look closely at whether alleged harm is supported by evidence and whether it is sufficient to justify refusal.
That does not mean that appeals will always succeed. Some proposals do cause genuine harm and are unlikely to be approved. The key issue is whether the council’s reasons for refusal are proportionate to the actual impact of the development.
When an appeal may not be the right approach
Not every refusal is worth appealing. Where a proposal clearly conflicts with fundamental planning principles, or where the impacts are obvious and significant, an appeal may simply confirm the council’s decision.
In some cases, revising the design or exploring alternative options may be a more sensible route. Honest advice at an early stage is important, particularly given the time and cost involved in the appeal process.
Next steps if your extension has been refused in Hillingdon
If your planning application for an extension has been refused by the London Borough of Hillingdon, it is often worth taking stock before deciding how to proceed. Understanding why the decision was made, and whether those reasons are likely to withstand independent scrutiny, is key.
If you are unsure whether an appeal is worth pursuing, we are happy to give an initial view.
For more information about planning appeals in Hillingdon, see our page on planning appeals in Hillingdon and this article on when it is worth appealing against Hillingdon Council.
For more on how to get planning permission for extensions, check out Martin Gaine’s bestselling book, How to Get Planning Permission: An Insider’s Guide.
