When planning an extension or renovation, it’s vital to grasp all the factors influencing the costs from the beginning. Understanding these elements helps avoid expensive errors later in the project.

Glorious Spaces can play a crucial role in helping you realise your dream space while staying within budget. Our extensive knowledge and experience will not only reveal what’s achievable but will also guide you through the expected financial implications, highlighting potential pitfalls to avoid.

How much does an extension cost in 2024?

Before you can get a clear idea of the costs involved in building an extension, you'll need to consider a number of variables. How big your extension is, for example, the materials you're using, the area of glazing, every choice will affect the final price when extending. However, it's important to be able to have a grasp on how much an extension costs to decide whether this is a viable project for you. With that in mind, we've created an easy reference which offers some ballpark figures you can use to begin forming your budget.

In short, building an extension is likely to cost around £1,500-£2,250/m² of new internal space (excluding VAT). So a 30m² kitchen extension could be estimated at somewhere between £45,500-£67,500, plus, VAT at 20%.

If that sounds rather general — that’s because it is. And that’s all you can expect when you have no detail or idea of what the extension looks like, or what materials you’re going to use, or how it is going to be built (and who’s going to do it). The £1,500-£2,250 price, however, is a good range of pricing based on averages.

And the good news is that there is huge scope to alter the overall cost significantly for the same-sized extension, depending on the choices you make for every element of the design, build and finish.

Use the estimated costs per square metre, plus the extra fees to calculate how much an extension will cost. You can also use our extension cost calculator to get a more detailed estimate of how much your extension will cost. Once you have this figure, more specific budgeting will assist to achieve a more accurate price, such as price per square metre of the interior fit out materials — like underfloor heating or flooring type, or windows.

For all extensions, you also need to allow for the cost of knocking through into the existing house and making good the connection, plus any other alterations or updates to improve the existing property, from rewiring and redecorating, to adding insulation or new doors and windows. Also, consider if you will be living inside the house during the building work, or if you need to rent a house elsewhere. These costs should all be carefully considered from the start.

SINGLE STOREY EXTENSION COSTS

If you're planning on building a fairly straightforward, box-shaped, then allow for around £1,500-£2,500/m² (excluding VAT). Do bear in mind that this price will fluctuate depending on where you are in the UK, the standard of build and the complexity of the design.

In certain parts of the South and high value areas of the UK – affected by higher cost of living – this you could easily be paying £1,700-£2,500/m², particularly on smaller single storey extension ideas. That makes an 8x4m kitchen extension a £43,000-£80,000 project.

• Standard quality: £1,500 to £1,750/m²

• Good quality: £1,700 to £2,100/m²

• Excellent quality: £1,800 to £2,500/m² or more.

For an excellent finish you can typically expect to pay 40% more than a standard finish.

To book your complimentary ‘In-Home’ Consultation, please follow the link below and our expert team will bring your ideas to life.