cost of extension

How Much Does An Extension Cost?

Are you planning on getting a home extension? But how much does an extension cost? It is essential to get an estimate so you can arrange finances. No matter, you are getting a conservatory extension, rear extension, or flat roof extension, various factors affect the cost such as materials, structures, utilities etc.

Typically, we do not consider our future requirements when buying a new home. The main concern for us is the budget, condition, design and home location. But at some point, our family get bigger, and we need more living space for the family. In such a situation, we have only two ways to get more living space: moving to a new big house, getting a house extension. In this article, we will only discuss the costs of different types of extensions.

Costs of Different Types of Extensions

The cost varies from one extension to another extension. Hence, having a plan in place will help you complete the job in your budget. For choosing an extension type, you first need to consider the architecture of your home and your requirements. Architecture is essential, especially if you are adding another floor to your home.

Single-Storey Extensions

Cost of Single Storey Extensions can range between £1000 per square meter to £1500 square meter. The cost of expansion depends on the type of material and design you choose.

Two Storey Extensions

In case of a two-storey extension, you need to add an extra 50% to the cost of single-storey expansion. For example, if the cost of a single-storey extension is £1500 per square meter, then you need an extra £750 per m2 to add another storey. However, the actual cost can get even higher than £1500 depending on the material you choose.

Loft Conversion

The cost of loft conversion is higher than adding a single-storey extension Because you need to insulate the space and need to make a few other alterations. In most of the cases, the cost of loft conversion range between £700 to £1750 per square meter depending on your requirements and amount of work.


Conservatory extensions consist of glass roofs, windows and other such attachments. These kinds of accessories can increase the cost of extension. Hence, it is essential to choose materials carefully that can protect you from the UK cold environment. Like any other extension, the cost of the conservatory also depends on the materials you use, and you can expect the cost of conservatory anywhere between £8000 – £9000. Furthermore, its design depends on the surroundings, so you need to get a detailed quote to get an accurate estimate of the cost.

Basement Conversion

Converting the basement into a comfortable living space can also be expensive. On average the cost of basement conversion can be anywhere between £1500- £2000 per square meter depending on the material and design. The builders need to be very careful with such conversion to make sure the property above is protected. That is one of the reasons that these types of conversions are pricey.

Garage Conversion

It is an affordable way to get some extra living space in the home. A garage already has a roof, walls, foundation and floor, so it costs less than other types of extension. You just need to insulate the walls and need to install a heating system to make it comfortable.

A standard garage conversion should cost between £5000 and £7500. Various factors affect the cost, such as repairs, modifications, materials, etc. If you have a complicated design, then expect to pay more than the standard conversion cost.

Cellar Conversion

A cellar conversion is also expensive and complicated as basement conversion. If you are converting an existing cellar, then it will cost you between £750 – £1400 per square meter. Because an existing cellar already have basic things like excavation and hence cost lower than creating a new one.

If you just need some minor changes to turn it into a room, then it will cost you less than the average cost. You should keep in mind that these cost estimates are averages. The actual cost of an extension depends on your requirements and the design. We are sharing this information to help you work on your budget. We always recommend our clients to have a 10% bugger for unexpected expenses.

Things to Consider

No matter what type of extension you want, there are some things that you need to consider. The first thing is a heating system, and insulation keeps the living space comfortable. So, keep in mind the cost of a heating system and insulation with every project. Another thing to consider is the cost of gas and piping. The quantity and quality of the materials can also affect the overall cost of the project. Last but not the least planning and building requires your time and effort. An architectural services provider considers certain variables while designing an extension. Furthermore, you need the approval of these plans from the local council.