How much does a home extension cost?

As you’d expect, there is not a straightforward answer to the question: how much will your home extension cost, but, we’re here to help you to navigate the considerations and budget you need to create your dream home. If, after reading this guide, you’d like some free advice, please book a discovery call with us.

Consider the variables

Before you can understand the true costs of building an extension, you need to consider the vast number of variables that will impact the project. These include the size of the extension you’re building, whether it is single or double storey, the materials such as glazing you would like, roofing, electrical and plumbing work required, and fixtures and fittings such as a new kitchen. You will also usually have to pay VAT for all elements of your project.

Also remember that you’ll need to allow for any alterations, such as knocking through onto the existing house plus any other modifications and improvements to your existing home such as insulation or new wiring. For example, a kitchen extension will normally cost more than just adding a habitable room, but can add significant value to your home in the long term.

When we meet with you, we’ll talk through the numerous options for your extension footprint and discuss the decisions that will affect your budget so that you can make an informed decision once you receive our estimate.

Professional Fees

In addition to the actual building and materials costs, you’ll also need to reserve some budget (usually around 10% of your build cost) for the various specialists that will be involved throughout the different stages of your project. These could include an architect, structural engineer, surveys and permissions approvals. As a design and build home extension specialist, we can outline all that’s required for your specific circumstances to ensure your home is built to stand the test of time and meets all current regulations.

Is there a guide price I can use to help me budget?

As a very rough guide, it costs on average around £3,000 (excluding VAT) per square metre to build a traditional single storey kitchen extension. Remember to also add around 10% for professional fees. Every home we work on is different and although we provide a detailed estimate at the start of your project, it’s important to be aware that costs may change as the project progresses based on decisions made during the process. You’ll be kept informed throughout all phases so you’re fully aware of the cost implications and options available to you.

Does it cost more to build a two storey extension?

A two storey extension will often cost around 60% more than a single storey, so we recommend a rough budget figure of around £4,800 per footprint square metre of the area of ground covered (not the total floor area). You may require further home modifications such as an internal reconfiguration though if building a double storey and so this needs to be factored in.

In general, smaller extensions will have a higher cost per square metre than a larger one as apart from the extra interior fixtures and finishes, you are only adding walls and floor joists. Foundations and roofing are required whether you opt for a small single or double storey and so these costs are largely the same whatever the height of your build. However, this cost does depend heavily on your specifications and the larger the extension, the higher your overall build costs will be.

Is it cheaper to manage the build myself?

Yes and no! At the start of a home renovation, you may feel that you’ve been able to save cost by appointing different trades for the various stages of your build but this is a very risky, time consuming way to complete your project. Will your tradesperson be available at the right time? Are they competent? Is their quote detailed enough and does it cover all that you need? Are there any unforeseen costs? Will the various suppliers communicate with one another and you? Do you know the right questions to ask and how to check if everything is up to standard throughout the project?

Building an extension can be complex with lots of unseen issues and requires detailed knowledge. If you’re thinking of doing this for the first time, we strongly recommend you carry out some detailed research and consider appointing a specialist building contractor like Stubbs Homes who can manage the whole project from start to finish. In our experience, homeowners are often left disappointed, stressed, and end up over budget when trying to manage a large build themselves.

I’ve got the budget in place, what do I do first?

It’s a good idea to get a contractor in at the very early stage of thinking about your extension. This way, they can help inform you and generate ideas based on their experience before you even get to the design stage. A reputable building contractor will often have a long lead time as they are busy working on other projects so be prepared that your extension may not start straight away. However, there is a lot of preparation involved and so you can get the ball rolling by gathering estimates and deciding on the best building contractor for your needs. Be sure to check out testimonials and ask for references before appointing your contractor to hear real-life experiences.

What can Stubbs Home offer?

We work with you from the outset right through to the completion of your project, managing the build, all of the required stages, and the various suppliers. We are design and build specialists and so provide advice, support and have the attention to detail that will make your dream home a reality. Want some free advice, get in touch to book a discovery call.