Various factors can impact the cost of a property extension in London. For instance, it’s important to note that the cost can change depending on where your home is located. A home extension in London is not going to cost the same as a home extension in the North of England. If you are thinking about changing your property such as adding an extension, then it is important that, as a starting point, you understand the type of costs that you’re going to be working with. 

Without knowing the exact details of your project, it’s difficult to predict the exact cost of an extension, but It’s worth noting that the average cost of an extension in London can be as low as £40,000 but can stretch upwards of £60,000. An average cost like this won’t be enough when planning your budget. Instead, you need to make sure that you are considering a wide list of other factors as well. 

You need to think about the type of extension that you want to build and add to your home in London. If you do this, you will be able to form an accurate and realistic picture of the type of costs involved. 

What Type Of Extension Do You Want?

It’s easy to treat all extensions as the same, but this isn’t the case. They can vary dramatically in a lot of ways. For instance, you could add an extension that is 5sqm or 100 sqm depending on how much space you have to work with and how much space you want to add. 

You might also be adding the extension to different areas of your home. For instance, you could choose to add an extension to the side of your home or think about building an extra storey on top of your home. This decision will often be determined by the space you have available and these key decisions are going to impact the price. 

The Starting Point In Your Budget

To get started with the costs of an extension in London, you must be aware that a basic extension will cost about £2000 for each square meter you want to add. That’s the average cost but it doesn’t take into account various other factors and variables. 

For instance, your design or idea for the extension might be quite complex. If that’s the case then it will take longer to build which could push up the price. You should think about the materials you are using too.

The main factor is always going to be the size. But even this can be impacted by other variables. As you work with a contractor on your extension, the size may increase, depending on the answers that you get from an expert. Or, it may decrease due to limitations on planning permission. 

Do You Need To Change The Rest Of The Home?

You might think it’s best to avoid completing any additional work on a property. However, some homeowners are always going to see an extension as an opportunity for bigger changes to their property. As well as this, it’s possible that more changes to your home will be necessary to ensure that the new extension and space fits as a seamless part of your living area. 

For instance, if you are building a conservatory, you might want to consider how this is going to blend in and fit as part of the rest of your home. 

Planning, Permissions And Approval

Once you have a basic understanding of how large your London home extension is going to be and the type of extension you want, it’s time to start thinking about planning it out with a professional. Remember, you must make sure that your extension does meet the right planning regulations. 

Smaller extensions are easier to get approval for. Larger extensions can be more complicated, particularly if your home is in a built up area. Any extension that is larger than 3 metres will need to be approved by the council and they will consult with your neighbors. 

If your extension is larger than six metres then you will have to ensure that you complete a planning application. This will cost just over £200. It’s not a massive addition to your overall bill, but it’s still worth keeping in mind. 

In total, you might need to put away up to £6,000 to ensure that you do have enough money for the planning stages of an extension on your London property. Particularly, if you want the best architect and contractors for a complex design concept. 

If you’re looking for more accurate costs bespoke to your extension in London, get in touch with Lucanu Construction builders in West London today. We specialise in building projects such as extensions, refurbishments, roofing and loft conversions in West London. 


We hope this helps you understand some of the key factors that you should be keeping in mind when working out the cost of your London home extension. If you’re looking for an extension in the West London area, get in touch with us today and we can discuss your expected project costs in more detail. 

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