Amalgamating flats into a single dwelling in the Royal Borough of Kensington and Chelsea is one of the most common enquiries we receive in the borough. On the surface, it often appears straightforward. In reality, RBKC applies a strict policy framework, and outcomes depend heavily on floorspace, planning history, and how the proposal is positioned.
This blog guide explains whether amalgamations are likely to be accepted, how to assess your own property against policy, and when alternative routes such as lawful development may offer a better strategy. It also draws on recent decisions across the borough to show how RBKC is currently determining these applications.
The starting point is Policy CH1 of the RBKC Local Plan 2019, which seeks to resist the net loss of residential units. However, there is a key exception under part (b).
RBKC will generally accept the amalgamation of 2 units into 1 where:
This 170m2 threshold is the single most important factor in determining whether an application is likely to succeed.
RBKC has a strong policy position on protecting housing stock. The borough is under pressure to retain smaller units, particularly flats, to meet housing demand.
Amalgamations are therefore only supported where they are modest in scale and do not significantly reduce the overall number of homes.
If your combined floorspace is below 170m2, the position is generally favourable.
Recent approvals in RBKC clearly demonstrate this:
23 Ifield Road was approved because the combined floorspace fell within the threshold, making the loss of 1 unit acceptable
43 Mary Place at 126.5m2 was approved with no external changes and no impact on the conservation area
76 Ifield Road at 131.64m2 was approved comfortably within policy limits
124 Lexham Gardens was approved at exactly 170m2, showing the threshold is applied precisely
These cases confirm that where the proposal sits within the policy limit, approval is highly likely provided there are no design or amenity issues.
RBKC strongly favours amalgamations that involve internal works only.
Many successful schemes share the same characteristics:
Examples include:
This reinforces a key point. The more discreet the proposal, the stronger the application.
Another strong route is where the proposal restores a property back to its original use as a single dwelling.
For example:
This approach aligns well with both local and national policy, particularly where historic subdivision is being reversed.
Once the combined floorspace exceeds 170m2, the position changes significantly.
The clearest example is:
The refusal was based on:
This case is important because it shows that policy is applied strictly, even where there are arguments around use.
RBKC does not generally support large-scale amalgamations because they reduce housing supply, they create large single dwellings in areas where smaller units are needed & they conflict with strategic housing objectives. As a result, proposals above 170m2 require a different strategy.
Where a property has already been used as a single dwelling for a continuous period, planning permission may not be required.
Under section 171B of the Town and Country Planning Act 1990, a use becomes lawful after 4 years if no enforcement action is taken.
This route has been successful in RBKC:
This is a key alternative where:
A lawful development application does not assess policy compliance in the same way as a full planning application.
Instead, it focuses on:
This allows applicants to bypass the 170m2 restriction where the use is already established.
One of the more interesting decisions is:
This exceeds the policy threshold, yet was granted permission.
The key difference was how the case was presented. The application argued that:
This suggests that in certain circumstances, RBKC may accept larger schemes where they are framed as existing use rather than new development.
However, this should not be relied upon as a standard approach.
Another consistent theme is the acceptance of returning properties to a single house format.
For example:
This reinforces the idea that policy is more flexible where the proposal aligns with the original building form.
Most properties in RBKC fall within conservation areas, which adds another layer of assessment.
In practice, this rarely prevents approval where:
Many of the approvals referenced were within conservation areas, including:
This confirms that conservation constraints are manageable in most amalgamation cases.
Measure the total Gross Internal Area of both units.
Check whether:
This can significantly influence the approach.
If the units have been used together as a single home:
This may avoid the need for planning permission altogether.
Ensure that:
This reduces risk and simplifies the application.
The most effective approach depends on your specific circumstances.
Submit a full planning application under Policy CH1(b). These are typically successful where well prepared.
Consider whether:
Avoid relying solely on planning policy in these cases.
Pursue a Certificate of Lawful Existing Use. This can be the most straightforward route where evidence is strong.
Amalgamations in RBKC are not difficult in principle, but they are tightly controlled.
The key lessons learned are simple:
Recent decisions show that RBKC applies policy consistently, but also that there is room for alternative approaches where the facts support it.
Understanding where your property sits within this framework is the first step towards a successful outcome. If you would like a consultation with our planning consultants, send us an email with your property address and a quick summary of the situation, and we will be happy to advise on the best approach, type of application and chances of success.
Call Us Today for a consultation: 02031500183 or email: enquiries@4dplanning.com
Please fill in the following form and one of our consultants will be in touch shortly...
Message Us