CAN I BUILD TWO HOUSES IN MY GARDEN?
Understanding whether a large garden could accommodate more than one new home
If you have a large garden, you may be wondering whether it could accommodate two houses rather than a single new dwelling.
Potentially, yes.
Some residential plots have enough space to accommodate two or more additional homes, but the number of houses that can physically fit is only part of the planning assessment.
The local planning authority will also consider whether the proposed development represents an appropriate use of the site, how it relates to surrounding development, whether suitable access can be achieved and the effect on both neighbouring properties and the existing house.
The best starting point is therefore to establish the realistic development capacity of the garden before designing a detailed scheme.
HOW BIG DOES MY GARDEN NEED TO BE FOR TWO HOUSES?
There is no universal minimum garden size for building two houses.
A site's development capacity depends on its dimensions, shape, location and surroundings as well as its overall area.
For example, a wide garden with direct road frontage might accommodate two houses relatively efficiently.
A larger but narrow rear garden may be more difficult because development needs to be reached through an access beside the existing house.
An initial assessment should consider whether the site can comfortably accommodate:
Two appropriately sized homes
Suitable access
Parking where required
Private gardens or amenity space
Refuse and cycle storage
Landscaping
Drainage
Appropriate relationships between the new homes
Appropriate relationships with existing neighbours
The amount and quality of garden remaining with the existing property also needs to be considered.
IS TWO HOUSES CONSIDERED OVERDEVELOPMENT?
Not automatically.
Overdevelopment is not simply determined by the number of homes proposed.
A two-house scheme on one site might appear cramped and inappropriate, while another garden could comfortably accommodate several homes.
The planning authority is likely to consider the overall quality of the development, including:
Building scale
Plot sizes
Spacing
Garden provision
Parking
Access
Landscaping
Relationship with neighbours
Local character
The important question is whether the site can accommodate two homes without the development appearing cramped or creating unacceptable impacts.
DOES THE EXISTING PATTERN OF DEVELOPMENT MATTER?
Yes.
The surrounding area can provide an important indication of what form of development may be appropriate.
For example, a street characterised by detached houses on wide plots may require a different approach from an area containing smaller plots, terraces or established infill development.
Useful characteristics to consider include:
Typical plot widths
Building lines
House types
Building heights
Spacing between buildings
Garden sizes
Density
Existing infill and backland development
The objective is not necessarily to replicate neighbouring buildings, but the proposal should normally respond appropriately to the established context.
CAN I BUILD TWO HOUSES BEHIND MY EXISTING HOUSE?
Potentially.
This would normally be a form of backland development.
Large rear gardens can sometimes provide sufficient space for more than one dwelling, but access and the relationship with surrounding homes become particularly important.
The proposed houses may need to share an access running alongside the existing property.
Consideration may therefore need to be given to:
Access width
Highway visibility
Pedestrian movement
Vehicle turning
Emergency access
Refuse collection
Noise from vehicles
Headlights
The proximity of the access to existing windows and gardens
As the number of homes increases, vehicle and pedestrian movements may also increase.
An access that may be appropriate for one additional dwelling is not necessarily suitable for several.
CAN I BUILD TWO HOUSES BESIDE MY EXISTING HOUSE?
Side gardens can sometimes provide particularly interesting development opportunities.
Where the land has direct road frontage, access may be easier to resolve than on a rear garden site.
The key question is often whether two additional houses would sit comfortably within the existing street.
This can depend on the width of the site, established building line, spacing between properties and the scale of neighbouring homes.
Different forms of housing can also use the land differently.
For example, two smaller semi-detached or terraced homes might sometimes provide a more coherent response than two detached houses squeezed into narrow plots.
The appropriate solution should emerge from the site rather than deciding the house type before assessing it.
DO BOTH NEW HOUSES NEED THEIR OWN GARDENS?
New houses will normally need appropriate private amenity space, although the amount and form will depend on the development and relevant local requirements.
This needs to be considered alongside the garden retained by the existing house.
A plan showing three houses fitting within the site can therefore be misleading if there is insufficient space left for usable gardens, access, parking and landscaping.
Amenity space should form part of the capacity assessment from the beginning rather than being whatever land remains once the buildings have been positioned.
HOW MUCH PARKING WILL TWO HOUSES NEED?
This depends on the location, type of homes proposed and relevant local requirements.
Some locations may require more on-site parking than others.
Parking can have a significant effect on garden development because cars, turning areas and access can consume a substantial proportion of a relatively small site.
A scheme should also avoid allowing parking to dominate the development or produce poor relationships between vehicles and private gardens.
For some sites, testing different housing types can help achieve a better balance between buildings, parking and landscaping.
WILL BUILDING TWO HOUSES AFFECT MY NEIGHBOURS?
Potentially, which is why the layout matters.
The proposal may need to consider:
Privacy
Overlooking
Outlook
Daylight and sunlight
Noise
Vehicle movements
Building height
Separation between properties
The position of windows
The relationship between new and existing gardens
These issues can become more complicated where several homes are introduced into an area previously occupied by a single garden.
However, careful positioning and design can sometimes resolve concerns that initially appear difficult.
CAN TREES REDUCE THE NUMBER OF HOUSES I CAN BUILD?
Yes.
Large gardens often contain mature trees and established landscaping.
Important trees can influence where houses, gardens, roads and drainage can be located.
A site that appears large enough for two or three homes on an aerial photograph may have a considerably smaller developable area once trees and their root protection areas are understood.
Where significant trees are present, it can therefore be sensible to understand their quality and constraints before progressing detailed architectural design.
WHAT ABOUT FLOOD RISK, DRAINAGE AND ECOLOGY?
These can all affect development capacity.
Even relatively small garden developments may need to consider how surface water will be managed and whether the development could increase flood risk elsewhere.
Established gardens can also provide habitats for wildlife, particularly where they contain mature trees, hedges, ponds or older buildings.
The presence of these constraints does not necessarily mean two houses cannot be developed, but they may influence the layout and supporting information required.
WOULD ONE HOUSE BE BETTER THAN TWO?
Possibly.
The objective should not automatically be to maximise the number of houses.
For some sites, two houses will clearly make better use of the land than one.
For others, a single larger dwelling may:
Have a stronger planning case
Require less infrastructure
Reduce impact on neighbours
Provide better gardens
Create a higher-quality development
Be easier or cheaper to deliver
The commercial outcome also matters.
Two smaller houses do not necessarily create more land value than one larger house once construction costs, planning requirements and infrastructure are taken into account.
This is why it is useful to consider planning, design and development value together.
COULD MY GARDEN ACCOMMODATE THREE OR MORE HOUSES?
Potentially.
If the site is sufficiently large, it may be worth testing more than two dwellings.
At this point, however, the proposal increasingly becomes a small residential development rather than simply creating an additional garden plot.
The requirements for access, drainage, landscaping, parking, biodiversity and other infrastructure can become more significant as the number of homes increases.
An indicative capacity study can compare several scenarios.
For example:
Option A — one larger house
Option B — two houses
Option C — three or more smaller homes
This can help identify which option represents the strongest planning and development proposition.
HOW DO I WORK OUT HOW MANY HOUSES MY GARDEN COULD ACCOMMODATE?
Rather than immediately commissioning detailed designs for two houses, start by understanding the site.
A useful initial assessment might consider:
1. Planning policy
Is additional residential development acceptable in principle?
2. Site context
What type and density of development surrounds the property?
3. Access
Can the proposed number of homes be safely and appropriately accessed?
4. Constraints
Are there trees, flooding, ecology, heritage or other issues?
5. Neighbouring properties
How much developable space remains once appropriate relationships are considered?
6. Capacity
What combination of houses, gardens, access, parking and landscaping can actually be accommodated?
7. Planning strategy
What is the most proportionate way of testing the development opportunity?
This provides a much stronger basis for deciding whether to pursue one house, two houses or a larger development.
SWAP VIEW
With larger gardens, we would normally test more than one development scenario.
The question is not simply:
“Can two houses fit?”
It is:
“What is the optimum development for this site?”
Sometimes that might be two detached houses.
Elsewhere it could be a pair of semi-detached homes, three smaller houses or a single high-quality dwelling.
By considering planning, architecture and development together, the aim is to find the option that makes effective use of the land while maintaining a credible planning case and sensible development proposition.
THINKING ABOUT BUILDING TWO OR MORE HOUSES IN YOUR GARDEN?
If you have a large garden, side plot or land behind your property, SWAP can assess how many homes the site may realistically be capable of accommodating.
We can review the planning position and site constraints and, where appropriate, test different development options before significant money is committed to a planning application.
Send us the property address, a plan if you have one, and a brief description of what you're considering.