Can you build in your garden? A guide to garden land and infill plots
Thinking of building a house in your garden or on a side, corner or backland plot? A plain guide to what the council will look at, the sums to run first and when to get advice.
PLANNING APPLICATIONS
Andrew Ransome
10/11/20266 min read
If you own a house on a generous plot, a corner site or a long back garden, you have probably wondered whether another home would fit, and whether the council would ever allow it.
This guide explains how these sites are judged, as the rules stand. It covers which sites qualify, what the council will look at, where schemes run into difficulty and which sites have more potential than you might expect.
The principle of development on garden land
Within a town or village, the principle is now favourable. The council is expected to approve a proposal within a settlement unless the adverse effects would substantially outweigh the benefits (NPPF Policy S4).
It must also give substantial weight to the benefit of creating additional homes within existing plots, including extra units within residential curtilages (NPPF Policy L2).
Outside settlements the position is tighter, and only certain forms of development are supported (NPPF Policy S5). Two of them matter here. The first is limited infilling within a group of houses. The second is the redevelopment of previously developed land.
Gardens in built-up areas are excluded from the definition of previously developed land. Gardens outside built-up areas are not, a point the courts have confirmed, so a house in large grounds in the countryside may qualify. However, different rules apply in the Green Belt.
In either location the support is conditional. The issues below are the conditions.
Character and street scene
The new development should be consistent with the overall street scene (NPPF Policy L2). In practice that means the building line, height and width, the gaps between buildings, plot widths and the treatment of the frontage.
National policy allows a departure from the street scene in three situations:
where a larger building is appropriate, for example on a street corner;
where the development would not be visible from the street frontage; and
where a design code in the development plan provides for specific changes.
This is the issue most open to judgement. Two planning officers can look at the same road and reach different views.
An application needs a clear analysis of the street as it stands, and drawings that show the new building in that context.
Backland development that cannot be seen from the street is not held to the street scene test. Its effect on neighbours and on the plot limits below still has to be addressed.
Access and highway safety
The scheme must maintain safe access and egress for occupiers and users (NPPF Policy L2). That covers cars, pedestrians, refuse collection and emergency vehicles, for the new home and for the existing one.
On backland plots this is often a critical issue.
A driveway running past the side of the existing house has to be wide enough, with adequate visibility where it meets the road. The noise and disturbance of vehicles passing close to the existing house and its neighbours is assessed as well.
Corner plots raise a different question: whether a new access can be formed safely close to the junction. Where a new access onto the road is proposed, the highway authority's comments tend to carry a lot of weight.
Neighbour amenity and living conditions
The scheme must maintain acceptable living standards for residents and neighbours, including daylight, sunlight, privacy and external amenity space (NPPF Policy L2).
Three sets of occupiers are considered:
the people next door,
whoever remains in the existing house and
whoever moves into the new one.
A scheme that protects the neighbours but leaves the existing house with a small, overlooked garden can still fail.
Window positions, separation distances and garden sizes do most of the work. Many councils publish their own standards for these, and they are applied alongside the national test.
Plot coverage: the footprint and open space limits
This issue is new in the 2026 NPPF policy, and it comes with numbers. Where development takes place within a residential curtilage, it should (NPPF Policy L2):
occupy no more than twice the footprint of all the existing buildings on the site; and
retain at least 50% of the non-developed area within the curtilage.
The existing buildings are measured as they stood when the policy was published in August 2026. Building an extension or outbuilding first, to raise the baseline, does not work.
The limits do not apply where additional development can be accommodated without harm to the overall character of the area, taking account of infrastructure and how sustainable the location is. The applicant should make and evidence the case; the council will not make it for you.
A substantial adverse impact measured against these curtilage tests is one of the situations where national policy says the benefits of a scheme are likely to be outweighed (NPPF Policy S4). The favourable starting point is then lost.
Density and efficient use of land
Within settlements, residential proposals should contribute to an increase in the density of the surrounding area, unless there is clear justification that this is inappropriate or not possible (NPPF Policy L3).
Existing character is still considered, but it should not prevent development that makes the most of an area's potential.
This cuts both ways. It supports two or three homes on a plot where the neighbours each have one. It counts against a single large house on a plot that could plainly take more, because proposals that do not make efficient use of land should be refused (NPPF Policy L3).
Sites near stations face a firmer test. Within about 800 metres of a well-connected station, housing schemes should reach at least 35 homes per hectare, or 45 where the service is at least twice the qualifying frequency.
Schemes of fewer than 10 homes can depart from these minimums where meeting them is shown to be inappropriate or not possible.
Local plan policies, design codes and site constraints
National policy is applied alongside the development plan for your area: the local plan, any neighbourhood plan and any design code.
These can pull in either direction.
A design code may provide for change that the street scene test would otherwise resist, and a local plan policy may set its own expectations on garden sizes, parking or character.
Site constraints carry their own policy tests, and any one of them can lead to refusal of a scheme that is acceptable on every issue above, for example:
protected trees;
conservation areas and the setting of listed buildings;
flood risk; and
Green Belt.
These need identifying before a layout is drawn, because they usually dictate where the building, the access and the gardens can go.
Garden land and infill development in the Green Belt
In the Green Belt the starting point is reversed. New building is inappropriate development unless it falls within a listed exception, and inappropriate development is approved only in very special circumstances (NPPF Policy GB6).
The first question is therefore whether an exception applies (NPPF Policy GB7). Five are relevant to garden land and infill plots:
Limited infilling in villages. This is the exception most garden and infill schemes rely on. Whether the place is a village, whether the site is a true infill plot and whether the scheme is limited are all matters of planning judgement. I cover each test in What is infill development in the Green Belt?
Redevelopment of previously developed land in the Green Belt, where it would not cause substantial harm to openness. A garden outside a built-up area may qualify.
Replacement or extension of an existing building. A replacement building must be in the same use and not materially larger, and an extension must not be disproportionate to the original building.
Grey belt land, where there is an evidenced unmet need for housing and the site is in a sustainable location.
Land within walking distance of a well-connected station, where the scheme is well related to the station or its settlement. This exception is new in the 2026 NPPF.
A scheme that fits an exception does not need very special circumstances, but the other issues in this article still apply.
A scheme that fits none faces a high bar: substantial weight is given to the harm to the Green Belt, and other considerations must clearly outweigh it.
Check first whether the village is “washed over” by the Green Belt or excluded from it. If it is excluded, Green Belt policy does not apply within the village boundary.
Get planning advice on your garden land or infill site
If you are considering a garden land or infill scheme, please get in touch. I can assess whether your site is eligible for development, identify the planning issues and advise on planning strategy and process.
Andrew Ransome MRTPI - Email: andrew@andrewransome.co.uk
About me
Andrew Ransome is a Planning Director and a Chartered Member of the Royal Town Planning Institute (RTPI), with more than two decades of experience in town planning.
He specialises in delivering strategic planning solutions for complex developments across both rural and urban environments, helping clients navigate planning challenges and unlock development opportunities. Connect with Andrew on Linkedin.
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