House Extensions Guide: Costs, Planning Permission & More

As our lives progress and families grow, the need for additional space in our homes becomes important. Whether you want to accommodate a growing family, add value to your property or create specific, functional rooms, extensions allow you to expand your home however you see fit. However, starting an extension project in the UK can feel like a momentous task.

Thankfully, with a touch of planning and foresight, the difficulties around this subject can be mitigated. This comprehensive guide aims to provide you with valuable insights into the world of house extensions. We’re going to explore everything from the reason why you might choose a house extension to planning permission considerations and cost breakdowns.

Why choose a house extension?

1. Create a new space

One of the main reasons homeowners choose house extensions is to address their growing space needs. Perhaps you want to accommodate a larger family, set up a home office or create a dedicated playroom for the kids. By making the most of your available space, a well-planned extension can transform your home for the better.

2. Extend instead of moving

We all know how stressful moving can be, not to mention expensive! House extensions offer a suitable alternative, allowing you to stay in the home you love whilst increasing your living space. This will not only save you the costs that come with moving but will also allow you to stay in a familiar setting.

3. Create specific rooms

Do you daydream about having a roomier kitchen, a luxurious master suite or a sunlit drawing room? House extensions are the perfect chance for you to bring these visions to life! By planning a customised extension project, you can design specific rooms that fit your lifestyle and preferences.

4. Adding value to the property

Investing in a well-designed and professionally executed house extension can massively increase the value of your property. The benefit here is twofold. Not only will this allow you to make use of the space while you live there, but it will also allow you to entice potential buyers when you do decide to move.

House extension cost breakdown

Before getting started with a house extension project, it’s important to have a clear understanding of the costs involved. The complete expenses of a project can vary depending on a few factors. Consider the size of your planned extension, the complexity of the room you want to create, the chosen materials and the location of your property. In the following sections, we’re going to look at some of the main costs to consider.

1. Design and planning costs

To get started, you’re going to need to hire an architect or a professional designer who can draw up plans for your house extension. The cost of this is usually somewhere around 5% to 15% of your total budget.

2. Construction costs

The construction costs of your extension will be a large percentage of your budget. This is because you must cover materials, labour and any specialised equipment that you’ll need for the build. You should know that on average, construction costs for a given room can range anywhere from £1,800 to £2,600 per square meter, depending on the complexity of the project.

3. Planning permission and building regulations

We’re going to go into more detail about Planning Permission in a later section of this post, but you should know that fees associated with this process will come into play. Getting planning permission and complying with UK building regulations is a vital step in any project and it usually costs £206 for a house extension application.

4. Contingency fund

You should consider setting aside 10% of your budget as a contingency fund. This will give you a safety harness in case anything goes wrong. In any extension project, there can be unforeseen issues or challenges during the construction process.

5. Fixtures and fittings

When it comes to house extensions, the choice of fixtures and fittings can significantly impact the overall cost. Luxurious touches, such as bespoke flooring, fitted joinery, or intricate tiling, undoubtedly add a touch of elegance and uniqueness to your extension, but they also come with a higher price tag. If you are working with a limited budget, opting for more basic designs like simply painted walls, standard lighting, and engineered wood floors can help keep costs in check without compromising on functionality and aesthetics.

Moreover, when planning to install additional features like a new bathroom or extended kitchen, it's essential to be prepared for the potential hike in costs. The required fittings and modifications for these extra amenities can add to the overall expenses of your extension project. Striking a balance between your desired fixtures and fittings and your budget will ultimately determine the success and satisfaction of your house extension endeavour.

House extension planning permission

Before you go ahead with your house extension, you must check whether you need planning permission or if you can proceed under permitted development rights. Permitted development allows you to undertake certain types of small-scale extensions without the need for formal planning permission. You should note, however, that there are requirements for size, location and appearance, including:

  • The extension and other outbuildings mustn’t cover more than half the area around the original house.
  • There should be no extension forward of the principal elevation or side elevation fronting a highway.
  • Side extensions must be a single storey with a maximum height of 4m and width no more than half the original house.
  • Rear extensions must be no more than 4m in height and not extend beyond the original house’s rear wall by more than 4m.
  • Upper floor windows must be obscure glazed on a side-elevation.
  • Materials should be similar to the appearance of the existing house.

For larger-scale extensions, there’s a good chance you will need planning permission. To do this, you’ll have to submit the details of your project (including detailed plans and documents) to your local planning authority. This can be a lengthy process, so it’s important to begin it as early as you can.

This process can get especially complex if you are looking to extend a listed or high-grade building. Getting your planned extension approved can be made easier by having detailed, extensive plans that cover everything your building authority needs to know. This is where you’ll need professional help from an architect or designer – more on this below.

How can an architect help with a house extension project?

Finding the right help for your house extension project is vital for its success. You need reliable experts who will help turn your dream into a reality. As well as hands-on contractors, an architect can add so much value to your project, including:

  • Making the most of the space you have available.
  • Turning your vision into a reality.
  • Obtaining planning permission as quickly as possible without compromising on your plans.
  • Sourcing skilled contractors from an already established network.
  • Project management to keep everything running smoothly.

Build your dream home with CODA Bespoke

Adding an extension to your house can feel like a big challenge, but with help from experts and a realistic quote, you’ll be much closer. CODA Bespoke is an award-winning architecture practice in Sheffield with a mission to make your dream house become a reality. With a focus on quality, innovation and forging a positive customer experience, we can help you with each stage of your extension project.

Contact CODA Bespoke to speak with our friendly, experienced team, or check out our extensive online portfolio to see the previous extensions we have turned into a reality.

© CODA Bespoke 151 Arundel Street, Sheffield S1 2NU