Residential Extensions in Enfield: The Planning Checklist
Expanding your home is a great way to unlock potential value and create the living space you’ve always dreamed of. However, in the London Borough of Enfield, achieving planning approval requires navigating a specific set of rules designed to protect the character of our neighbourhoods.
If you are planning a project, you will need to align with two key documents: the Development Management Document (DMD), specifically Section 2.5, and Core Policy 4 of the Core Strategy.
Core Policy 4 is the borough's overarching policy on Housing Quality. It demands that all residential developments adhere to high standards of design and sustainability. This means your extension shouldn't just be "big enough"; it must be safe, accessible, environmentally sustainable, and visually integrated with the existing architecture.
Below is our technical checklist for the four main types of residential extensions permitted in Enfield.
1. Rear Extensions (Policy DMD 11)
Rear extensions are the most common project type, but they can easily impact a neighbour's light or privacy. The Council uses specific geometric rules to prevent this.
The Checklist:
Single Storey Depth:
Terraced & Semi-Detached: Maximum depth of 3 metres beyond the original rear wall.
Detached: Maximum depth of 4 metres beyond the original rear wall.
Single Storey Height:
Flat Roof: Maximum height of 3 metres from ground level to the eaves (allowance of 3.3m–3.5m to the top of a parapet wall).
Pitched Roof: Maximum height of 4 metres at the ridge and 3 metres at the eaves.
The 45-Degree Rule (Single Storey): The extension must not cross a line drawn at a 45-degree angle from the midpoint of the neighbour's nearest original ground-floor window.
The 30-Degree Rule (First Floor): Extensions at the first-floor level must not cross a line drawn at a 30-degree angle from the midpoint of the neighbour's nearest original first-floor window.
Alignment: You may be required to secure a "common alignment" of rear extensions with your neighbours to maintain a consistent building line.
Amenities: The design must ensure no negative impact on the amenities (light, outlook, privacy) of the original building or neighbours.
Parking & Garden: You must retain adequate garden amenity space and satisfactory access to existing garages or parking spaces.
2. Outbuildings (Policy DMD 12)
Garden rooms, home offices, and gyms fall under this category. They must remain subordinate to the main house.
The Checklist:
Usage: The building must be strictly ancillary (secondary) to the residential use of the dwelling.
Position: It should not project forward of the front building line.
Distance: Adequate distance must be maintained from the main dwelling.
Topography: The design must respect the natural lay of the land (topography).
Impact: The size, height, and bulk must not adversely impact the character of the local area or the amenities of neighbours.
Core Policy 4 Alignment: Ensure the design quality and sustainability of the outbuilding matches the high standards expected for the main dwelling.
3. Roof Extensions and Dormers (Policy DMD 13)
Loft conversions are excellent for adding bedrooms, but bulky "box" dormers are generally resisted. The policy focuses on keeping additions "subordinate" to the original roof.
The Checklist:
Inset Dimensions: Dormers must be inset from the eaves, ridge, and edges of the roof. The required inset is typically between 500mm and 750mm.
Scale: The extension must be of an appropriate size and located strictly within the roof plane.
Character: The design must not appear dominant from the surrounding area and should align with the character of the property.
Side Dormers: These must not disrupt the balance of the property or the group of properties (e.g., upsetting the symmetry of a semi-detached pair).
Front Dormers: These are generally not permitted unless they do not materially affect the character of the area and are not dominant or intrusive.
4. Side Extensions (Policy DMD 14)
Side extensions allow for widening a home but carry the risk of the "terracing effect"—where gaps between semi-detached homes are filled, creating a solid wall of buildings along a street.
The Checklist:
Separation Distance: You must maintain a minimum distance of 1 metre from the boundary with the adjoining property to prevent the terracing effect. A greater distance may be required depending on the plot size and local character.
Façade Continuity: The extension must not result in a continuous façade that is out of character with the locality.
Corner Plots: If your home is on a corner, you must maintain a distance from the back edge of the pavement on the return frontage. This is assessed based on:
Established building lines and vistas to the rear.
The need for adequate visibility splays for traffic safety.
The bulk and dominance of the structure (it must remain subordinate).
Retention of adequate amenity space.
Core Policy 4: The Golden Thread
While the checklists above give you the parameters, Core Policy 4 provides the philosophy. It dictates that high quality design and sustainability are required for all housing developments.
When designing your conversion or extension, consider:
Sustainability: Are you using energy-efficient materials and construction methods (exceeding Code for Sustainable Homes Level 3 standards where applicable)?
Accessibility: Does the design support the principles of Lifetime Homes? Even for extensions, considering adaptability for future needs (e.g., wheelchair access) is encouraged and supports the borough-wide target of making 10% of new homes wheelchair accessible.
Visual Quality: Does the extension preserve the architectural integrity of the original house?
This guide is based on the Enfield Development Management Document (2014) and Core Strategy (2010). Planning policy is subject to change and interpretation by planning officers. Always seek professional advice for your specific project.
