How to Plan a Home Extension

Are you in need of extra space? Whether you’ve expanded your family, are sick of constant clutter or are struggling to find some peace and quiet, many of us could do with some extra room in our homes.

A home extension is one of the best ways to add extra space and increase the value of your property, but the task can seem daunting. However, an extension can be a great option with the right planning and preparation and it’s often less hassle than moving house. If you’ve been thinking about adding an extension to your home and want to know where to start, see below for our handy guide.

Do I need planning permission?

It depends; some extensions are covered by what’s known as permitted development rights, but rules and regulations apply. A detached house can be extended by up to eight metres at the rear (or three metres if it’s a double storey). Semi detached or terraced houses can add a rear extension of up to six metres without planning permission.

As a general rule, you will need planning permission under the following conditions:

  • If the extension covers half (or more) of the land surrounding your home
  • If you’re extending towards a road
  • If your single storey extension is taller than four metres
  • You’re increasing the overall height of the building
  • If you plan on adding a balcony
  • You plan on using different materials to the original house
  • If you live in a listed building or on a conservation site.

You can submit an application for planning permission yourself, or your chosen builder or architect can do it on your behalf.

Building regulations

You’ll also need to think about building regulations when planning a home extension. All extensions need to comply with regulations, which mostly cover a building’s structural stability.

Most homeowners choose to arrange a survey from a structural engineer. They’ll be able to assess your plans and the site of the extension to make sure it complies with all building regulations. These include aspects like the foundations, window and door openings, beams and roof structures. It’s important to make sure you comply with all regulations before the work starts, to avoid disrupting the project or add extra time and expenses.

How much does a home extension cost?

The cost of a home extension can vary greatly, depending on the size, the location and the design. Expect to pay around £1,000 to £2,000 per square metre for a single storey extension. Second storey extensions aren’t actually that much more expensive, as you’re only adding additional walls and floor joists. A roof and foundations are some of the most costly aspects and these are required for a one storey extension regardless.

Make a list of what you’d like included in your extension (e.g one or two storeys, size, materials) and source at least three quotes from different contractors before going ahead. Experts also recommend adding an extra 10% to your budget for any unexpected costs.

Funding options

Extensions can be expensive, but there are several finance options to consider if you don’t have a large cash sum upfront. Remortgaging your property is one way to release some extra funds for a home extension project. A remortgage allows you to borrow more money upfront and you can stick with your current provider or switch to a new lender.

You could also take out a second mortgage, although it’s likely that you’ll need to pay fees and there are long term repayments to consider. A home improvement loan is another popular option to finance an extension project and you can choose either a personal loan or a secured loan. You can find more detailed information about home improvement loans on the Money Supermarket website here.

Designing your extension

Designing an extension isn’t just about aesthetics, although decorating the interiors is a fun part of it. Your extension design needs to include a lot of practical elements, including the floor plan, roof height, window and door placement (and construction), the materials used and the foundations.

Many homeowners choose to work with an architect to help them design their extension and this is usually the best way to ensure your project is fully compliant. An architect can provide detailed drawings of your building and they’ll be able to turn your ideas into a practical reality. You may also want to consult a structural engineer for technical drawings and calculations. These can be used in your building regulations application and by your architect and builders during the project.

Things to consider when designing your extension include:

  • The footprint – how big do you want the floor area to be? Keep planning permission conditions in mind and consider how much space you’d like left in the garden.
  • Extension height – do you want a double or single storey extension? You’ll also need to think about the roof height and the materials you’ll use.
  • Building materials – do you want your extension to blend in with the rest of your house? Or will you choose modern materials to make it stand out? You may need planning permission if your extension contrasts with the design of the original building or if you plan on using completely different materials.
  • Interiors – ideally, the ceiling height between your original property and the extension should be the same. You’ll also need to make sure flooring is level to create a seamless, open space.

Building the extension

Once you have your extension plan and have acquired all the relevant planning permissions, it’s time for the fun bit – building the extension! You can expect a relatively simple, single storey extension to be completed in around three to four months. More complicated designs or double storey extensions take around five to seven months, but each time frame will depend on the individual project.

You can expect your extension to be built in the following stages:

  • Laying the foundations/groundwork
  • Installing gullies and soakaway to manage surface water
  • Construction of internal and external walls
  • Installation of electrical and plumbing facilities, guttering and piping
  • Plastering of the walls
  • Light fittings, switches and sockets
  • Installation of taps, connections and appliances
  • Fitting of carpets or flooring
  • Decoration!

Ideas for your extension

There are many exciting uses for your home extension depending on your needs. A kitchen is one very popular option for a home extension, especially if the area opens up into the garden. An open kitchen/dining room is a great addition to your home and it provides extra space for entertaining.

Many more people have been working at home over the past year, so perhaps you need space for a home office? A conservatory extension or a design with large glass windows is ideal for a home office and you can have some peace and quiet away from the main house.

If you’re feeling ambitious, then a two storey extension adds the maximum amount of space. You could create a designated bedroom and bathroom for guests, or add a luxury extra like a cinema room or playroom.

Domestic foundation construction from the experts at Below Ground

Are you a homeowner planning a home extension? If you’re in need of a reliable foundation and piling contractor, get in touch with the team at Below Ground. We’re proud to offer domestic foundation construction for homeowners in London, Bristol, Exeter and beyond.

We’ve got a wealth of experience in the conception, design and construction of foundations based on structural engineering designs. We’ll make sure that you’re always in compliance with building regulations and we can build entire foundations, or add piles and reinforced beams alone. We offer all of our clients a 12 year guarantee and pride ourselves on competitive prices, so give us a call today or contact us online to discuss your next project.