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House Extension Cost London and Hertfordshire United Kingdom

Updated: Mar 18

If you are planning or considering a house extension in 2024 one of the factors you are probably wondering about is what your house extension project will cost in 2024? Here we will look at costs associated with building an extension. In this article we will take a look at the cost of a house extension in 2024. This article will cover, average costs of a house extension in 2024. factors that can affect the cost of a house extension, costs per sqm of a house extension, different types of house extensions and illustrations of what they can cost. There are also links to many completed house extension projects by LCCL Construction.


House Extension Cost London and Hertfordshire
House Extension Cost London and Hertfordshire

What is the cost of building a house extension in London and Hertfordshire?


There are many factors that can affect the end cost of an extension build, such as location, size, required finish, type of extension and layout of the existing house. Generally speaking homeowners can expect to pay £1800-£3000 per square metre for a house extension in 2024. For most house extension projects this means the cost could be between £45,000 and £75,000. Factors that will have a big influence include variables such as how much space you intend to add to your home. Most extensions are calculated on a cost per square mere basis so planning to add a 30m2 extension is going to cost more than a more modest 18m2 extension. Other influencers that will come into play can include how open plan you want the space to be, what alterations you would like to make to the structure of the existing house and what the new space is to be used for, the type, quantity and specification of glazing.


For instant cost on various types of house extension projects including rear house extensions, kitchen extensions, side return extensions, wrap around house extensions or loft and house extensions instant cost calculator



Will a house extension add value to my home?


Another frequently asked question by home owners considering an extension project is whether the new space will add value to their property. To find out more information on this topic see our blog post on the topic: Will a house extension add value to my home?


Types of house extension and what they cost


 Our handy 3D illustrations of the various types of house extensions could help you to identify the type of house extension that would be best suited to your property. There's also a guide to what they can cost to build in 2024. You will gain an understanding of the different types of design and build construction projects that we offer at LCCL Construction. If you are looking for more in depth information on the of different types of house extension projects that can be found on the following links rear house extensions, kitchen extensions, side return extensions, wraparound extensions, ground floor extensions, rear and side house extension and loft conversions and house extensions project as a whole.


Rear House Extension or Kitchen Extension
Rear House Extension or Kitchen Extension

Design and Build rear house extension or kitchen 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

  • Open plan 2 to 7 meters




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

  • Open plan 2 to 7 meters





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

  • Open plan 2 to 7 meters





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

  • Open plan 2 to 7 meters




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

  • Open plan 2 to 7 meters




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

  • Open plan 2 to 7 meters





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

  • Open plan 2 to 7 meters




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





Factors that can affect the cost of your extension


There are many factors that can affect the end cost, here are some to consider when budgeting for your extension project:

  • Project location - there are likely to be regional variations to the cost of your extension. Everything from the cost of materials, labour, premises and fuel may be subject to regional variations.

  • Size - extensions can vary greatly, from a small addition of just a couple of metres to a full two storey wraparound adding 60+ square metres of space.

  • Layout of existing house - are you planning to make substantial changes to the original house such as removing a galley kitchen and supporting walls to achieve an open plan layout with the new extension.

  • Condition of existing services - will you be looking to replace the electrics and plumbing such as the boiler during the extension build.

  • Glazing - The size and specification of glazing can vary greatly in price depending on what you choose, there are many options for all budgets though.

  • Kitchen - Typically a new kitchen is purchased and fitted during the extension build, the size, brand and design of the kitchen, type of counter tops and splash backs, from bespoke handmade kitchens to high street brands to budget friendly options there is a wide selection available to choose from.

  • Adding bathrooms - A popular add on during an extension is to include a new bathroom/downstairs toilet.



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 17 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.


Where would you like to go next?


Get started or get to know us better, we are sure we will be able to help you..

check out our knowledge base 

Telephone: 020 8037 7332

Email: info@lcclconstruction.co.uk


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