Those looking to build their own home probably know that one of the main hurdles for self build projects is typically the availability of land, particularly in the south east where much of the land is designated green belt — one of the strongest barriers of development within the planning system.

As a consequence, one of the most popular methods for building a home of your own is via the replacement dwelling method: finding a house or bungalow in a poor state or a property with potential and applying for a replacement dwelling on the site.

Benefits of Replacement Dwellings

The main benefit of this approach in planning permission terms is that the principle of development is already established. Therefore, there can be no policy arguments about the suitability of the site for residential development and ‘all’ that is to be agreed with the local planning authority (LPA) – whether that’s a district council, borough council, city council, unitary authority or national park – is design.

This upfront understanding that the principle of residential development is acceptable comes with a number of benefits:

1. You can guarantee you will get planning permission to build something

If you purchase a property with a view to building a replacement dwelling you can be sure that you will get permission for something. Therefore, it leaves just the details such as design, scale, siting and access. However, these are not necessarily straightforward to agree with any LPA and there are many additional complexities involved.

2. It is a way to build in areas where planning for a new build on a new plot would be unlikely

A further and significant benefit is that this mechanism can be used to gain planning permission for a dwelling in an area that might not normally be allowed. For example, sustainability is considered the ‘golden thread’ running through the National Planning Policy Framework (NPPF).

In planning terms, ‘sustainability’ relates primarily to the location of the development — would future residents of the dwelling be reliant on their car to go about their day-to-day business or could they walk, cycle or get public transport to work, to school, to the shops and so on?

As you might imagine, the principle of sustainable development puts quite a restriction on the potential for development in rural areas, and indeed many locations outside established settlement boundaries. It is such restrictions that keep the countryside open and prevent rural areas being inundated by individual dwellings.

However, the replacement dwelling proposal in an isolated or rural area would not be subject to the same restrictions, since the principle of residential use has already been established by the existing dwelling. As far as planning is concerned, a proposed replacement dwelling would not increase the number of car trips and so does not add to the ‘unsustainability’ of an area.

Replacement Dwelling Case Study

bungalow before it was replaced with a new build home


Planning Success: Karen Fairholme and Nigel Brookes demolished a 1920s bungalow in Derbyshire (above), replacing it with a five-bed contemporary property (top). Planning permission had originally been granted for an extension to the original bungalow, but when it became apparent that it would be more cost-effective to demolish and rebuild, the couple had to reapply for planning permission.

“The constraints of the plot also required us to build within the same footprint of the old bungalow, and the height of the new building was limited as it had to be lower than the neighbouring houses,” says Nigel.

Local Circumstances

Despite replacement dwellings being acceptable in principle across England, the extent of what can be achieved can still vary wildly from place to place and from each local planning authority. This is because planning policy varies locally and local circumstances, such as the context and character of the area, will vary.

While all LPAs must adhere to the NPPF, they must also implement their own local development plan. This document is often typically known as the local plan, development plan or core strategy.

Each LPA’s local development plan adds policy meat to the NPPF’s bones and determines the number of houses and amount of employment land to be built in a district over the plan period. It will usually allocate specific sites for such development, as well as including development control policies against which future planning applications in the district will be judged.

The types of policies that a LPA will include in its local plan will vary depending on a number of factors. For example, an urban district will have more of an emphasis on growth, providing employment and places to live than a very rural district, where the emphasis might be more on preservation of the openness and the area’s bucolic character. Policies contained within the local plan will reflect these needs.

How Local Policy can Affect a Replacement Dwelling Project

When it comes to a replacement dwelling proposal, although national policy dictates that the principle is acceptable nationwide, the exact extent of what can be achieved will differ from location to location.

Local policy is a significant factor — some LPAs work to strict guidelines regarding how much larger than the original a replacement dwelling can be. A figure of 130 per cent is not uncommon, meaning that the new dwelling can only be the size of the original dwelling plus an extra 30 per cent floorspace, whereas others are more pragmatic and will consider a proposal against the local context.

The exact guidelines to which a LPA will work is very seldom published in policy form. It is usually best to speak to the LPA, which may be via a pre-application enquiry, to determine their approach.

In green belt areas a policy of 30 per cent increase is not common. However, some LPAs are even more restrictive about what can be achieved in the green belt. Sevenoaks District Council, for instance, only permits replacement dwellings in the green belt where: ‘the volume of the proposed replacement dwelling, including any new or retained extensions or outbuildings, would not exceed the volume of the ‘original’ dwelling by more than 30 per cent (measured externally)’.

So, Sevenoaks does not allow more than a 30 per cent increase on the size of the original dwelling — either as it was built or as it was in 1948. If a property had been extended, the extensions cannot be counted when calculating the allowed 30 per cent increase in floorspace.

There are other variations of replacement dwelling policy. The South Worcestershire authorities, for example, apply the 30 per cent rule to all replacement dwellings in the open countryside, but are more relaxed about what can be achieved within an existing settlement. While Herefordshire only allows replacement dwellings in countryside ‘that [are] comparable in size and scale with … the existing dwelling’.

Outside green belt areas, unless a LPA works to strict guidelines, the pragmatic approach outlined above will usually be employed. Thus factors such as the street scene, the pattern and grain of development, the proximity of and potential on neighbouring properties, and the local vernacular will be the most important factors. So a bungalow could be replaced by a much larger property if the proposed dwelling would fit the local context and would not impact greatly upon the street scene.

However, it is unlikely that a two-storey dwelling would be permitted where the neighbouring properties were bungalows, as the proposed dwelling would be out of keeping with the street scene, look incongruous in the local context and likely be overbearing to immediate neighbours.

Using Permitted Development to add Floorspace to a Replacement Dwelling

Where replacement dwelling policy or local context is restrictive in terms of the increased floorspace of a replacement dwelling, there are other methods that can sometimes be employed to gain additional floorspace. For example, Permitted Development rights still apply in the green belt. Under current Permitted Development regulations, it is possible, depending on circumstances, to extend a dwelling by more than 50 per cent, sometimes up to 100 per cent.

Where this is viable, it can be possible to approach the LPA and ‘negotiate’ a higher increase in allowed floorspace than the 30 per cent normally deemed appropriate in the green belt for a replacement, in return for not extending the existing property to the full extent of the Permitted Development allowance.

If you can make the argument that the replacement dwelling will have less of a negative impact on the character of the local area than what may be achieved under Permitted Development, particularly at its maximum threshold, then some LPAs will be inclined to consider the proposal. For replacement dwellings where height is a restrictive factor due to the local vernacular, a basement may be a way of achieving extra floorspace without negatively impacting on the street scene.

So, while the NPPF sets out planning policy for the entirety of England to which all English LPAs must abide, there are still significant variations on what can be achieved on a place-by-place basis. But one fact remains: a replacement dwelling can deliver the sort of self build opportunity that might not otherwise be achievable in the area.

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