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House Extension Types

Updated: Feb 7

Everything you need to know about house extensions in London and the United Kingdom, including the different types of rear extensions there are, what are the planning rules, costs associated when building a house extension and questions to bare in mind before starting your project.


House Extension Types London, United Kingdom
House Extension Types London, United Kingdom

What is a house extension?


House extension is really an umbrella term encompassing multiple different types of extensions but generally it just means an extension for the purpose of creating a larger kitchen/dining/living space or extra bedrooms at the rear or side of the property. It can be single storey or include scope to add addititional space to multiple storeys of the existing home. The way we use our homes currently is very different to how they were intended to be used when constructed. Everything from modern appliances to working arrangements to the way we socialise and the age at which children leave home has affected the way we desire our homes to be arranged. Typically kitchens in older homes were one of the smallest rooms of the house used solely for the purpose of food preparation, out of sight from any visitors, a cramped and drab space for a solitary cook hidden away from the rest of the family. This dull utilitarian picture could not be further from how we use our kitchens now. Galley kitchens are out and large social spaces where friends and families can cook, socialise, do homework, relax and even work from home are in. We have also seen a trend for removing the laundry elements from the kitchen and adding a utility room where space allows or a utility pod where space is limited. This reduces noise levels in the kitchen and allows for great storage utilisation in the kitchen area. This has obviously had a big impact on the way kitchens and extensions are designed. Adding open plan spaces to properties that were built with multiple smaller rooms at the rear requires careful architectural design and critically this design must be supported by accurate structural drawings and calculations. At LCCL Construction we deliver all of these services efficiently and expertly as part of our design and build package.


House extensions are often considered to be the best way forward for home owners in the United Kingdom who don't want to move but are in need of extra space for their kitchen, dinning, living or socialising areas. It is no surprise that we have seen a high demand especially in London areas for rear house extension and people seeking to add additional space to their property.


In the United Kingdom there are many different types of house extensions that can be designed and built. In London where there are many different types of properties the architecture can be tailored to maximise the space and efficiency of the layout for each individual property creating truly unique spaces.


If for you it is a priority to have open plan, larger kitchen or dining areas, or additional downstairs rooms such as a utility then extending your home would be an excellent choice. The house extension can easily create additional space in the back and/or side of your house.


The house extension can be created on terraced houses, end of terraced houses, semi detached houses or detached houses including Period style properties, Edwardian, Victorian or modern homes.


What are the benefits of a house extension?


Whether your aim is to increase the kitchen size, add an extra bedroom and bathroom upstairs, add living space, a utility room or create a ground floor bedroom to meet the needs of your family the advantages of a house extension are numerous:

  • Utilise otherwise unused space to increase the size of the home.

  • Improved saturation of natural light in the downstairs areas through addition of skylights/lanterns

  • Added flexibility to the layout of the home

  • Increase the number of bedrooms

  • Create space for a large open plan kitchen diner and casual living space where everyone can spend time together

  • Add a study space to work from home

  • Increase the number of bathrooms in the home

  • A generously sized utility room can be added to free up space in the kitchen and reduce noise from washing machines/dryers

  • Add a boot room to reduce dirt and clutter cominh into the house

  • Create much needed extra storage space

  • A new patio at the rear or private courtyard can be created at the side

  • Extra 16m2 to 100m2 of additional space

  • Improve the layout efficiency and flow of the home to suit everyday life

  • Potential for additional space to be added to the first floor too in some circumstances

  • Extra storage and usable space for everyone in the home to enjoy


What type of space can I add to my home?


There are many layout options available to homeowners looking to add a house extension to their home. Several factors come into play when settling on the final layout


The size and layout of the existing home

  • Whether you want to make moderate or substantial adjustments to the structure of the existing house or alternatavely add space with minimal structural and or layout alterations to the existing house

  • How much budget you have available for the project

  • If the desired extension is single storey or multiple storeys

  • If you are looking to achieve an open plan layout/partially open plan or to add multiple rooms


Do I need planning permission for my House Extension?


In many cases it is possible to build a house extension as a permitted development project, subject to specific criteria being met. This is not always the case though depending on the size and scale of the extension and in some cases a full planning application will need to be made to your local planning authority. At LCCL Construction our expert team will be able to help guide you through the process.

Rules, known as ‘permitted development’ rights, allow you to extend a house without needing to apply for planning permission if specific limitations and conditions are met.


For all extensions:

  • Only half the area of land around the "original house"* can be covered by extensions or other buildings.

  • Extensions cannot be higher than the highest part of the existing roof; or higher at the eaves than the existing eaves.

  • Where the extension comes within two metres of the boundary* the height at the eaves cannot exceed three metres.

  • Extension cannot be built forward of the ‘principal elevation’ or, where it fronts a highway, the ‘side elevation’.

  • The work cannot include:

  • verandas, balconies or raised platforms.

  • a microwave antenna (e.g. TV aerial or satellite dish).

  • a chimney, flue or soil and vent pipe.

  • any alteration to the roof of the existing house.

  • On Article 2(3) designated land* the work cannot include cladding of the exterior.

  • The materials used in any exterior work must be of a similar appearance to those on the exterior of the existing house.


For single storey extensions:

  • Single-storey rear extensions cannot extend beyond the rear wall of the original house* by more than four metres if a detached house; or more than three metres for any other house.

  • Where not on Article 2(3) designated land* or a Site of Special Scientific Interest; and subject to ‘prior approval’, the limit for single-storey rear extensions is increased to eight metres if a detached house; or six metres for any other house.

  • This requires that the relevant Local Planning Authority is informed of the proposed work via a prior approval application.

  • Single-storey rear extensions cannot exceed four metres in height.


For Extensions more then one storey:

  • Extensions of more than one storey must not extend beyond the rear wall of the original house* by more than three metres or be within seven metres of any boundary* opposite the rear wall of the house.

  • Roof pitch must match existing house as far as practicable (note that this also applies to any upper storey built on an existing extension).

  • Any upper-floor window located in a ‘side elevation’ must be obscure-glazed; and non-opening (unless the openable part is more than 1.7 metres above the floor).

  • All side extensions of more than one storey will require householder planning permission.

  • On Article 2(3) designated land* all rear extensions of more than one storey will require householder planning permission.


Below are some of the different types of house extensions, you can click on the links to find out more about each types of house extension, planning implications and costs involved:



House extension with pitched roof features - the pitched roof would be covered in roof tiles such as clay, concrete of slate tiles, velux lights can be installed to the pitched roof, at the rear of the wall there can be various types of glazing but the most common are bi-fold doors, sliding doors, crittall or french doors. The finish of the exterior walls comes in render, brick finish or cladding such as zinc clad. In addition the patio towards the rear of the property can be added. Open plan internally for open plan living, WC underneath the stairs and utility area for your laundry.


House extension with flat roof features- the features include same as above except the flat roof would have flat roof skylight or lantern added instead of velux windows. The flat roof waterproofing systems would be either out of GRP waterproofing systems or roofing felt.

Internally the house extension can have a large kitchen with the kitchen island, underfloor heating, upgraded electrical and plumbing solution.


The most common house extensions in London and the Hertfordshire area and rest of the United Kingdom are as follows. Below are some of 3d examples of the house extensions costs and the costs associated with the design and build of the house extensions:



Flat Roof Rear House Extension
Flat Roof Rear House Extension

Design and Build 3 x 3 meter rear house extension at rear of the property.


Estimated cost: from - £45,000.00


Optional Extras:

  • Skylight or small lantern

  • Bi-fold doors

  • Kitchen

  • Floor finishing

  • Patio at rear of the property

  • Downstairs Bathroom





Small Side Extension Pitched Roof
Small Side Extension Pitched Roof

Design and Build Small Side Extension Pitched Roof.


Estimated cost: from - £48,000.00


Optional Extras:

  • 2 x Velux

  • Bi-fold doors

  • Kitchen

  • Floor finishing

  • Patio at rear of the property

  • Downstairs Bathroom





Small Side Extension Pitched Roof
Small Side Extension Pitched Roof

Design and Build Small Side Extension Flat Roof.


Estimated cost: from - £49,500.00


Optional Extras:

  • Skylight or small lantern

  • Bi-fold doors

  • Kitchen

  • Floor finishing

  • Patio at rear of the property

  • Downstairs Bathroom





Small Rear Extension Flat Roof
Small Rear Extension Flat Roof

Design and Build Small Rear Extension Flat Roof.


Estimated cost: from - £48,000.00


Optional Extras:

  • Skylight or small lantern

  • Windows

  • Bi-fold doors

  • Kitchen

  • Floor finishing

  • Patio at rear of the property

  • Downstairs Bathroom





Medium Side Extension Pitched Roof
Medium Side Extension Pitched Roof

Design and Build Medium Side Extension Pitched Roof.


Estimated cost: from - £55,500.00


Optional Extras:

  • 3 x Velux

  • Bi-fold doors

  • Kitchen

  • Floor finishing

  • Patio at rear of the property

  • Downstairs Bathroom





Medium Side Extension Flat Roof
Medium Side Extension Flat Roof

Design and Build Medium Side Extension Flat Roof.


Estimated cost: from - £54,000.00


Optional Extras:

  • Skylight or medium lantern

  • Bi-fold doors

  • Kitchen

  • Floor finishing

  • Patio at rear of the property

  • Downstairs Bathroom






Large Side Extension Flat or Pitched Roof
Large Side Extension Flat or Pitched Roof

Design and Build Large Side Extension Flat or Pitched Roof.


Estimated cost: from - £63,000.00


Optional Extras:

  • 3 x Skylights on flat roof or 4 x Velux on Pitched Roof

  • Bi-fold doors

  • Kitchen

  • Floor finishing

  • Patio at rear of the property

  • Downstairs Bathroom




3 meter rear house extension with flat roof at rear of the property
3 meter rear house extension with flat roof at rear of the property

Design and Build Terraced 3 meter rear house extension with flat roof at rear of the property.


Estimated cost: from - £47,800.00


Optional Extras:

  • Skylight or small lantern

  • Bi-fold doors

  • Kitchen

  • Floor finishing

  • Patio at rear of the property

  • Downstairs Bathroom




3 Meters Crown Roof Rear Extension
3 Meters Crown Roof Rear Extension

Design and Build Terraced 3 meter rear house extension with crown roof.


Estimated cost: from - £59,500.00


Optional Extras:

  • 4 x Velux

  • Bi-fold doors

  • Kitchen

  • Floor finishing

  • Patio at rear of the property

  • Downstairs Bathroom




Flat Roof Small Wrap a Round Extension
Flat Roof Small Wrap a Round Extension

Design and Build Flat Roof Small Wrap a Round Extension.


Estimated cost: from - £64,000.00


Optional Extras:

  • 1 x Skylights or Lantern on flat roof

  • Bi-fold doors

  • Kitchen

  • Floor finishing

  • Patio at rear of the property

  • Downstairs Bathroom





Pitched Hip Roof Small Wrap a Round Extension
Pitched Hip Roof Small Wrap a Round Extension

Design and Build Pitched Hip Roof Small Wrap a Round Extension.


Estimated cost: from - £65,000.00


Optional Extras:

  • 2 x Velux Windows

  • Bi-fold doors

  • Kitchen

  • Floor finishing

  • Patio at rear of the property

  • Downstairs Bathroom





What is the cost of the loft conversion and house extension?

You can use our "instant quote calculator" and find out the cost in seconds! for both design and build, architecture services or just construction services depend what stage you are in and what you have so far completed.


We have experience of over 15 years in design and construction of loft conversions and home extensions in London and Hertfordshire areas and have worked out a unique calculation formula that you can find out to what your house extension and loft conversion will cost in seconds.


How can Lccl Construction be of help?


Do you require a loft conversion and house extension to add extra space?

Then look no further get in touch with us for a detailed free no obligation quote. We can accommodate a very quick turnaround. Our loft conversions and house extensions come with 10 year guarantee and 12 month workmanship guarantee.


Use our instant quote calculator for a quote about your project whether construction only or design and build.


Use our Free consultation call booking system to schedule a call at the time and date that suits you best.

Telephone: 020 8037 7332

Email: info@lcclconstruction.co.uk

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