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6/9/2020

How much does a house extension cost? How long does it take to build a house extension?

16 Comments

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House extension cost guide

​Rule of thumb, extension prices can start from £1,100 per square meter (plus VAT) and rise well over 2600 per square meter (plus VAT) depending on factors such as quality of the house extension (basic, good, excellent) and complexity of construction, specification, features, shape, size, number of storeys, drainage, layout,  site (trees, soil type, access, slope), location etc.  For example a narrow and small extension will be more expensive than a square and big extension. The same extension in London will cost more than somewhere else. Kitchen cabinets, sanitary, appliances will add to price as they will vary depending on quality and your taste. 

You may also need to consider if you can live in the house during the construction and if not, how this would increase the cost. 

The following costs can be added additionally to a house extension costs:
  • Drawings and structural calculations for planning and building regulations (start from £800)
  • Party wall agreement (around £1000 if it is agreed surveyor)
  • Insurance cost
  • Any internal alterations, rewiring, asbestos removal, new boiler system, decorations etc

Example 1: A single storey house extension or kitchen extension cost:
18 square meter (6m*3m) Single storey rear extension fully integrated with main house to provide open-plan living space, with bi-fold doors, roof lantern, and flat roof: Around £27000 plus VAT (20%), plus kitchen cabinets and sanitary. 
The house extension work can take around 2 months depending on site and weather situations. 

Example 2: A double storey house extension cost:
A double storey extension per square meter will be cheaper than a single storey extension as roofing and foundation cost can be similar. (Scaffolding will need to be added)
36 sqm (6m*3m) double storey rear extension: Around £50000 plus VAT (20%), plus kitchen cabinets and sanitary. 
The house extension work can take around 3 months depending on site and weather situations. 

​
These are for only guidance. 
Remember, it's important to get multiple quotes for house extensions!

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16 Comments
James Morrow link
6/14/2021 04:51:07 am

Great article! Thank you for sharing this informative post, and looking forward to the latest one.

Reply
Ratu Knight link
7/28/2021 06:45:23 am

What an exquisite article! Your post is very helpful right now. Thank you for sharing this informative one.

Reply
home extension builders link
5/17/2022 05:40:55 am

When choosing the rooms for your house addition, it's crucial to think about their function first and then match the layout design to those goals. Size is crucial, but form may be just as vital. An L-shaped arrangement, for example, may be ideal for a bathroom but not so much for a bedroom. It's also a good idea to think about furniture selections and how they could alter the room's form. If you already have clear ideas about the contents of a space, you'll need to change the form to accommodate them.

Reply
Residential Elevators South Carolina link
10/24/2022 09:03:25 pm

Thankk you for sharing this

Reply
https://pbcpainters.com/ link
10/12/2023 06:36:37 pm

I think you ve made some truly interesting points. Not too many people would actually think about this the way you just did.

Reply
ASPHALT & BITUMEN SURFACING IN CANBERRA link
12/6/2024 07:48:20 am

Informative post! It's useful to be aware of how living arrangements during construction can impact the total cost.

Reply
ASPHALT SURFACING LITHGOW link
12/9/2024 05:30:46 am

The additional costs and time estimates are crucial for anyone considering a home extension project.

Reply
Spray & Seal Bitumen Cowra link
12/31/2024 01:51:38 am

The breakdown of costs and considerations is incredibly helpful for planning an extension.

Reply
Pothole & Grading Surfacing Hornsby link
1/2/2025 02:03:01 am

I appreciate the clear examples and additional costs to consider. This makes planning an extension much easier.

Reply
ROAD CONSTRUCTION Canberra link
1/20/2025 02:31:23 am

Appreciate the advice on getting multiple quotes. The additional cost considerations are also very useful.

Reply
HARDSTANDS SURFACING Gundagai link
1/20/2025 03:13:29 am

Appreciate the thorough explanation of single and double storey extension costs. The practical tips on living arrangements during construction are very useful.

Reply
Spray & Seal Bitumen Griffith link
2/19/2025 07:47:16 am

Appreciate the detailed guide! Knowing how elements like size, shape, and location impact extension costs can save time and avoid surprises

Reply
Driveway Resurfacing Hitchin link
3/4/2025 10:09:36 am

Thank you for this informative breakdown of extension costs! It’s helpful to see all the factors that can influence pricing. Planning ahead for additional expenses like party wall agreements and structural calculations is definitely a smart move. If you're also considering upgrading your driveway to complement your new extension, feel free to visit our site—we’d love to help!

Reply
Spray & Seal Bitumen Blayney link
3/24/2025 05:39:58 am

Very informative! The variation in cost based on location and complexity really helps set expectations. I’ll definitely be considering these details when planning my own extension.

Reply
Tar & Chip Surfacing Letchworth Garden City link
4/4/2025 09:42:39 am

Thank you for this insightful breakdown of house extension costs! It’s helpful to understand the various factors that can influence the price, from location to the quality of finishes and the complexity of the project. Knowing these details allows homeowners to make more informed decisions when planning an extension. If you happen to need a driveway to complement your new space, feel free to visit our site for expert driveway services!

Reply
Driveway Contractor Near Me link
4/17/2025 11:20:19 pm

Thank you for providing such a detailed breakdown of house extension costs! It’s incredibly helpful to have a clear understanding of how various factors, such as the size of the extension, materials, and location, can affect pricing. It’s also useful to consider the additional costs for things like drawings, structural calculations, and internal alterations. If you happen to need a driveway for your newly extended space, feel free to visit our site for more information!

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  • Home
  • Services
    • Building Regulations Applications
    • Build Over Agreements
    • Party Wall Agreements
    • Planning Applications
    • Permitted Development
  • Overheating
    • TM59 Overheating Assessment
    • The Simplified Method
    • TM52 Overheating Assessment
    • Energy Assessment
  • Commercial
    • Change of Use
    • Signage Applications
  • Residential
    • House Extensions
    • Loft Conversions
    • New Build House
    • Outbuildings
    • Garage Conversions
    • Flat Conversions
    • HMOs
  • Process
  • APPLICATIONS
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