Types of House Extension | Complete Guide to Extension Types

Types of House Extension in the UK

A house extension is one of the most effective ways to add valuable living space to your home without the expense and disruption of moving. Whether you need an extra bedroom, a larger kitchen, or a dedicated home office, there is an extension type to suit every property and budget. At Fixiz Ltd, we deliver all types of house extensions across North London, from rear extensions to full double-storey builds.

Rear Extension

A rear extension is the most common type of house extension in the UK. It extends the back of your property to create additional ground-floor living space. Rear extensions are particularly popular for enlarging kitchens, creating open-plan kitchen-diners, or adding a utility room or downstairs bathroom.

Key Features of Rear Extensions

Extends from the back of the property into the garden
Can be single-storey or double-storey
Single-storey rear extensions up to 6 metres (detached) or 3 metres (other property types) may fall under permitted development
Ideal for creating open-plan living and kitchen-diner layouts
Typical cost ranges from £30,000 to £60,000 for a single-storey rear extension

Rear extensions are especially popular across North London boroughs such as Barnet, Enfield, and Haringey, where Victorian and Edwardian terraced houses benefit greatly from additional ground-floor space.

Side Return Extension

A side return extension utilises the narrow alleyway that runs along the side of many terraced and semi-detached properties. This often-wasted strip of land, typically between 0.9 metres and 1.5 metres wide, can be incorporated into the existing ground floor to create a significantly wider living area.

Key Features of Side Return Extensions

Makes use of the narrow side passage alongside the property
Creates a noticeably wider kitchen or living room
Often combined with a rear extension for maximum impact
Usually falls under permitted development rights
Typical cost ranges from £20,000 to £40,000

Side return extensions are particularly popular in areas like Islington and Camden, where narrow Victorian terraced houses have significant unused side passages that can be transformed into additional living space.

Wrap-Around Extension

A wrap-around extension combines a rear extension with a side return extension, creating an L-shaped addition that wraps around the corner of your property. This type of extension delivers the maximum amount of ground-floor space and is ideal for creating large, open-plan kitchen-living areas.

Key Features of Wrap-Around Extensions

Combines rear and side return extensions into one project
Creates the maximum ground-floor living space
Perfect for open-plan kitchen, dining, and living areas
May require planning permission depending on size
Typical cost ranges from £40,000 to £70,000

Double-Storey Extension

A double-storey extension adds living space on two levels, providing significantly more floor area than a single-storey extension. This type is ideal for families who need both additional living space on the ground floor and extra bedrooms or bathrooms on the first floor.

Key Features of Double-Storey Extensions

Adds living space on two levels simultaneously
More cost-effective per square metre than two separate single-storey extensions
Typically adds one to two additional bedrooms plus ground-floor space
Almost always requires planning permission
Typical cost ranges from £50,000 to £100,000 or more

Double-storey extensions are common in areas like Barnet and Brent, where detached and semi-detached properties have sufficient garden space and structural capability to support two-storey additions.

Over-Structure Extension (First-Floor Extension)

An over-structure extension, also known as a first-floor extension, builds above an existing single-storey ground-floor structure such as a garage, kitchen extension, or flat-roofed outbuilding. This is an efficient way to add first-floor space without requiring additional foundations.

Key Features of Over-Structure Extensions

Builds above an existing single-storey structure
No additional ground-floor footprint required
Structural survey needed to confirm existing structure can support the additional storey
Planning permission usually required
Typical cost ranges from £25,000 to £50,000

Orangery or Garden Room Extension

An orangery is a brick-built extension with a lantern-style roof that floods the interior with natural light. Unlike a conservatory, which is predominantly glazed, an orangery has solid brick walls with large windows and a partially glazed roof. This makes orangeries suitable for year-round use as they offer better thermal performance.

Key Features of Orangery Extensions

Brick walls with large windows and a lantern roof
Better insulation and temperature control than a conservatory
Suitable for year-round use as a living room, dining room, or home office
Adds significant aesthetic appeal and property value
Typical cost ranges from £25,000 to £55,000

Which Type of House Extension Is Right for Your Home?

The best type of house extension depends on your property layout, available garden space, budget, and what you want to achieve. Here is a quick comparison:

Best for budget: Side return extension (from £20,000)
Best for maximum space: Double-storey extension
Most popular: Rear extension (versatile and cost-effective)
Best for terraced houses: Side return or wrap-around extension
Best for natural light: Orangery or garden room extension
Best value per sqm: Double-storey extension

Planning Permission and Building Regulations

Many single-storey rear extensions fall under permitted development rights, meaning you may not need to apply for planning permission. However, the permitted development limits vary depending on your property type, and there are restrictions in conservation areas and on listed buildings. Double-storey extensions, front extensions, and large wrap-around extensions almost always require a full planning application.

All house extensions must comply with Building Regulations regardless of whether planning permission is needed. Building Regulations cover structural integrity, fire safety, energy efficiency, drainage, and accessibility. At Fixiz Ltd, we manage the entire Building Regulations process on your behalf, including applications and all necessary inspections.

Get a Free House Extension Quote

If you are considering a house extension in North London, Fixiz Ltd can help you choose the right type of extension for your property and budget. We offer free site surveys, detailed quotes, and expert advice on planning requirements. Contact us today to discuss your project.

Call us: 020 XXXX XXXX | Email: info@fixiz.co.uk