What are infill plots?

Mike Dade explains how you can tell whether an infill plot is suitable for self-build
by Mike Dade
25th November 2012

There’s no formal definition of what makes an infill plot, although one frequently adopted by councils for countryside locations is ‘the infilling of a small gap within an otherwise built-up frontage or group of houses.’

A ‘small gap’ would usually be big enough for only one, or at most two, houses set in plots of a broadly similar width to those next door.

The word ‘within’ indicates that the site should normally have houses on either side and not be an add-on to a row of houses.

An ‘otherwise built-up frontage’ suggests a pretty dense and uniform pattern of development, rather than a loose grouping of houses with lots of gaps and spaces in between, so ‘group of houses’ must apply to situations where there is development in depth, such as a tight-knit cluster of housing.

So, it would seem that an infill plot has a fairly broad definition, could typically be a large side garden, an area of outbuildings between two houses, or maybe an access way and some redundant garages.

Where can you find suitable infill plots?

Whether you can build on an infill plot depends very much on its location and the policies that apply there, to be found in the council’s local development framework (LDF) or old-style Local Plan.

If you spot a promising infill plot, look at the plans attached to the Local Plan or LDF, to be found on the council’s website or at their offices, which will include a document of policies together with maps showing where those policies apply.

The maps showlines drawn around built-up areas, known variously as development boundary, settlement boundary, built-up-area boundary and so on.

The lines are usually drawn fairly tightly around the main built-up areas of towns and villages and often exclude peipheral areas of low-density housing. Which side of such a line an infill plot lies has a big influence on whether you can build on it.

Read more: Complete guide to finding a plot

Within development boundaries

Arts and crafts brick house in Lonodn

The Orchard is a new two-storey family house in the London Borough of Lambeth, which was built to fit into a narrow infill plot along a terrace of five architecturally distinct houses.

The vision was to build a contemporary interpretation of the Arts & Crafts house combining 21st century energy and environmental performance with a commitment to traditional craftsmanship.

more about this project

Inside towns’ and villages’ development boundaries, most councils’ policies allow for infilling and small-scale development. Some define categories of settlements, from larger towns down to small hamlets, with differing rules for each.

Contrary to the political and media hype, there generally remains encouragement to build at higher densities, despite recent ‘anti-garden grabbing’ measures.

Government planning policy still allows for building in gardens in built-up areas, and most councils still allow infill development, including in side gardens.

There are, however, areas in towns and villages where infill is restricted. These might be conservation areas or areas with some special character, which the council wants to preserve.

This doesn’t necessarily mean you can’t build, but permission is going to be harder to come by and there are likely to be design constraints as well, particularly in conservation areas.

Read more: 10 expert tips to win planning permission on a garden plot

Outside development boundaries

Outside the boundaries, on the edges of towns and villages and in hamlets and small settlements, there’s no general rule on how infill is treated.

Some councils have specific policies allowing infill where there are more than a certain number of houses in a row. Others specify areas on their Local Plan maps where infill might be allowed, such as built-up road frontages and ribbons of development.

Many councils elect to keep life simple and allow no new housing at all, infill or not, outside development boundaries.

This means it’s essential to check the policy status of a plot, before making assumptions about whether you can build on it. Always look at the Local Plan or LDF first.

Assessing an infill plot

Assuming you’ve found a potential infill plot in an area where infill development is allowed, how do you know what you can build on it?

The things to look at are the types of houses on either side of the site and in the area generally, the pattern of development, whether there will be privacy between the plot and neighbouring properties, whether the new house will be excessively overbearing or cause overshadowing, access, and finally any particular features of the site such as a slope, trees, existing buildings and so on.

Read more: Land appraisal – infill plot in Buckinghamshire 

Neighbouring houses

You can get a good idea of what can be built on an infill plot by looking at its two neighbouring properties.

If they’re bungalows, the likelihood is you’ll have to build a bungalow, although you might be able to stretch to a chalet with the first-floor rooms in the roof. If the neighbours are houses, then another house would probably fit in best.

There are no hard and fast rules, but an infill house must fit in with its neighbours to a reasonable degree.

Read more: Council politics and planning permission

Pattern of development

This refers to the sizes of plots and the position of houses within those plots.

If the pattern is close-knit, you might be able to squeeze an infill plot in a gap of little more than 10 metres between houses.

If the pattern is more spacious, a house that was too crammed in might look out of character and would be resisted by the council.

The same goes for position in the plot. If all the houses in the road are set well back, then your infill house should be too.

Sometimes, if an infill plot is narrow, the garage has to be set in front of the house. In many situations this would be quite in keeping but in some the garage might appear to intrude forward of a perceived building line, and so be refused.


The key questions here are: would the plot have adequate privacy; and, most importantly, would a new house on the plot affect the privacy of neighbours?

Hedges and fences usually protect privacy at ground floor level, so the issues tend to arise from upstairs windows either looking into neighbours’ windows or down into their private garden space.

Privacy issues rarely affect whether a plot can be built on, but they do affect how.

Windows must be carefully positioned to avoid overlooking. Often this means putting obscured glazing in landing or bathroom windows on the sides of the house, with the main bedroom windows facing to the front and rear.

Read more: Planning solutions to overlooking issues

Overbearing and overshadowing

An infill house is bound to have some effect on its neighbours in reducing the light to their windows and perhaps to their gardens.

There’s a fine line between what’s a reasonable level of overshadowing and what’s not. Look at the neighbouring houses carefully to see where the windows of the main rooms are.

If the main living room or kitchen windows are on the side of the house, you might have to site the new house a little farther from the boundary to ensure it won’t restrict light too much.

In the same way, a new house could be regarded as overbearing if it’s too close to another. Although no one has a right to a ‘view’, planners do get concerned about the more nebulous concept of ‘outlook’.

Where a house enjoys an open outlook, hemming it in with a new house might be seen as being harmful to the amenities of the occupants.


Infill sites are often narrow, making it difficult to provide adequate access, on-site turning (where necessary) and parking.

An integral garage can save space, and sometimes it’s possible to share a drive with a neighbour, if they are the ones selling the plot.

Parking requirements are less onerous these days and in central areas of towns, where there’s good public transport available, on a really small plot it might be possible to build without any on-site parking at all.

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