CAN I BUILD A HOUSE IN MY GARDEN?
Planning permission for building a new home in a garden
If you have a large garden or unused land beside your home, you may be wondering whether you could build another house in your garden.
In many cases, the answer is potentially yes.
Garden land can sometimes provide an opportunity for one or more new homes, but having enough physical space for a house does not automatically mean planning permission will be granted.
The local planning authority will consider the principle of development, the character of the surrounding area, access, neighbouring properties, trees, ecology, parking and the design of the proposed home.
The first step is therefore to establish whether the garden represents a credible development opportunity before spending significant money preparing a planning application.
DO I NEED PLANNING PERMISSION TO BUILD A HOUSE IN MY GARDEN?
Yes. Creating a separate new dwelling will normally require planning permission.
This is very different from constructing a normal domestic extension or certain outbuildings associated with an existing house.
A new independent home is a separate planning unit and needs to be considered as a residential development proposal.
The planning authority will assess both whether development is acceptable in principle and whether the proposed house is appropriate for the particular site.
IS MY GARDEN BIG ENOUGH TO BUILD A HOUSE?
There is no single garden size that determines whether another house can be built.
The shape and arrangement of the land can be just as important as its overall area.
A relatively compact but well-proportioned side garden may provide a straightforward opportunity, while a much larger rear garden may be difficult to develop because of access or its relationship with neighbouring properties.
An initial assessment should consider whether there is sufficient space for:
The proposed house
Suitable access
Parking where required
Private amenity space
Refuse and cycle storage
Landscaping
Appropriate separation from existing homes
Trees and other site constraints
It is also important to consider the amount and quality of garden remaining for the existing house.
The relevant question is therefore not simply “Is my garden big enough?”, but “Can an appropriate development be accommodated on it?”
WHAT IS GARDEN DEVELOPMENT?
Garden development involves constructing one or more new homes on land forming part of an existing residential property.
This could involve:
Side garden development – a new house alongside an existing property.
Rear garden development – development within a large rear garden.
Backland development – development behind existing properties, often using a separate access.
Infill development – filling a suitable gap within an established pattern of buildings.
The planning considerations can be quite different depending on which type of site you have.
A side plot with direct road frontage may, for example, present fewer access issues than a rear garden requiring a new driveway between existing houses.
DOES MY GARDEN NEED ROAD FRONTAGE?
Not necessarily.
A site with direct frontage onto an existing road can make access relatively straightforward, but backland development can sometimes be possible behind existing houses.
In these cases, the ability to create a suitable access becomes particularly important.
The planning and highway implications may include:
Access width
Visibility
Pedestrian safety
Vehicle movements
Turning space
Emergency access
Refuse collection
Noise and disturbance to existing properties
A narrow driveway beside an existing house does not automatically rule out development, but it can influence both the number and type of homes that might be appropriate.
WILL MY NEIGHBOURS STOP ME BUILDING A HOUSE?
Neighbours can comment or object to a planning application, but an objection does not itself determine whether planning permission will be granted.
The planning authority will consider the relevant planning issues raised.
For garden development, these commonly include:
Overlooking
Loss of privacy
Outlook
Daylight and sunlight
Noise
Increased vehicle movements
The scale and position of the proposed building
The relationship between new and existing gardens
Good design can make a significant difference.
Changing the position, orientation, height or window arrangement of a proposed house can sometimes overcome issues that would otherwise make development difficult.
DOES THE CHARACTER OF THE AREA MATTER?
Yes.
Planning authorities will normally consider how a new dwelling relates to the established pattern and character of development around it.
Relevant characteristics can include:
Plot widths
Building lines
Spacing between houses
Building heights
House types
Garden sizes
Density
Landscape character
A new house does not necessarily need to copy neighbouring properties, but it should normally have an appropriate relationship with its context.
Existing examples of garden, infill or backland development nearby can also be useful when assessing the opportunity.
CAN I BUILD BEHIND MY EXISTING HOUSE?
Potentially.
Large rear gardens can sometimes accommodate backland development, particularly where suitable access can be achieved.
However, rear garden development can raise issues that do not arise with a conventional street-fronting plot.
A new house may be closer to neighbouring gardens and existing homes, while its access may pass alongside an existing property.
The layout therefore needs to consider both the new dwelling and the effect of introducing residential activity into an area previously occupied by gardens.
Some locations already contain established backland development, which can provide useful context when considering whether further development may be appropriate.
CAN I BUILD MORE THAN ONE HOUSE IN MY GARDEN?
Potentially.
Larger plots may be capable of accommodating two or more homes.
However, development capacity should not simply be determined by how many building footprints can physically fit onto the land.
As the number of homes increases, greater consideration may need to be given to access, parking, gardens, refuse, landscaping, drainage and relationships between both new and existing properties.
A capacity study or indicative site layout can help test different options before committing to detailed design.
Sometimes one larger home may provide a stronger development proposition than two smaller houses.
On other sites, several homes may represent an entirely appropriate use of the land.
CAN TREES PREVENT GARDEN DEVELOPMENT?
Trees can significantly influence what can be built, particularly where mature trees occupy or surround the potential development area.
Some trees may be protected by a Tree Preservation Order, while additional controls can apply within Conservation Areas.
Even where a tree is not formally protected, its quality and contribution to the character of the site can still be relevant.
The roots and canopies of retained trees can also affect where buildings, roads and drainage infrastructure can be positioned.
Where significant trees are present, understanding their implications early can prevent a scheme being designed around an unrealistic developable area.
WHAT ABOUT ECOLOGY AND BIODIVERSITY?
Ecology can be relevant even on relatively small residential sites.
Established gardens may contain trees, hedges, ponds, buildings or other habitats with ecological value.
Depending on the characteristics of the site and the proposal, ecological surveys or other information may be required.
Biodiversity requirements can also influence how development is designed and landscaped.
This does not necessarily prevent development, but it should form part of the feasibility assessment rather than being considered only after a scheme has been designed.
WHAT HAPPENS TO MY EXISTING HOUSE?
This is easy to overlook.
Creating a new building plot changes the existing property as well as creating a new one.
The remaining house still needs an appropriate:
Garden
Access
Parking arrangement where required
Relationship with the proposed development
Level of privacy and amenity
A scheme that provides a good new house but leaves the existing property with an unacceptable arrangement may struggle to obtain permission.
It can also affect the value of the existing house.
The potential value created by the new building plot should therefore be considered alongside any reduction in the value or amenity of the original property.
HOW MUCH COULD A GARDEN BUILDING PLOT BE WORTH?
There is no standard value.
The value of a potential building plot depends on what can be developed and the economics of delivering it.
Factors can include:
Location
Planning status
Size and type of house
Local house values
Construction costs
Access
Site conditions
Planning requirements
Demand from developers and self-builders
Land with planning permission will generally present a more certain proposition than land where the principle of development remains unresolved.
However, formal valuation advice should be obtained where an accurate value is required.
SHOULD I GET PLANNING PERMISSION BEFORE SELLING PART OF MY GARDEN?
It can be worth considering.
Selling part of a garden without planning permission transfers much of the planning risk to the purchaser.
Establishing planning permission yourself may create greater certainty about what can be developed and could affect the value of the land.
But obtaining permission also involves cost and risk.
It can therefore be sensible to assess the planning opportunity first and decide how far to progress it before marketing the land.
WHAT SHOULD I DO FIRST?
Don't start by commissioning detailed architectural drawings for a house simply because it appears to fit.
A more proportionate first step is usually to establish:
Is the principle of another dwelling realistic?
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What are the main planning and site constraints?
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Where could access be provided?
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What form and scale of house might be appropriate?
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Would one or more homes represent the strongest option?
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What is the most appropriate planning route?
Once those questions have been considered, detailed design work can be targeted at a much better-defined development opportunity.
SWAP VIEW
Garden sites can look deceptively simple.
There may be a large area of apparently unused land, but the real development opportunity is determined by the relationship between planning, access, neighbours and design.
We would therefore normally assess the planning position and constraints before designing a detailed house.
The objective is to determine whether there is a credible building plot, what type of development suits it and the most proportionate way of establishing planning certainty.
Sometimes the result is one house.
Sometimes a larger site can accommodate several.
And sometimes identifying a fundamental constraint early can save the landowner from spending thousands of pounds pursuing an unrealistic proposal.
THINKING ABOUT BUILDING A HOUSE IN YOUR GARDEN?
If you have a large garden, side plot or land behind your home, SWAP can assess whether it may have development potential.
We combine planning, architecture and development experience to consider the planning position, potential access, site constraints and what form of development might realistically be achievable.
Send us the property address, a plan if you have one, and a brief description of the part of the garden you're considering.