How to plan a home extension

Bright kitchen area with big flat roof windows that allow lots of sunshine in the room
Running out of space at home? Before you start scrolling property websites to find somewhere new, consider building an extension. It’s often the most cost and time-effective option, especially if you love living in your current neighbourhood. You can create more space, improve the quality of life for your family and boost your property’s value, without the hassle of a big move. There’s a lot to think about to make sure you end up with a space that ticks all the boxes for your growing family, so read on for our guide to planning a home extension.

Identify your vision

A successful home extension starts with a clear vision. You know you need more space, but what do you need that space to do? What works in existing rooms and what doesn’t? What problems does the extension need to solve? Perhaps you’re dreaming of an open-plan kitchen and living room for big family gatherings, desperate for a utility room or a playroom for the kids, or want a multi-functional space that can handle everything from home working to overnight guests. Get clear on your needs before you meet with an architect or builder so they can design a plan that meets your needs.

Get inspired

This is the time to dream big and make a wish list. Have fun diving into all things extensions in home magazines, renovation shows and on Instagram and Pinterest to get ideas and a feel for your style and taste. Visit friends who’ve done extensions to get a tour and their best tips for renovation success.

Create a budget

A carefully balanced budget will help make sure you end up with an extension that ticks all the boxes without costs spiralling. Take your wishlist and figure out what’s a must-have versus a nice-to-have feature. Now do costings for everything from a builder, architect, materials, planning fees and decoration - you may need to adjust your wishlist after this task! Don’t forget to allow for a contingency fund too. Get the lowdown on how to budget for a home extension in this article.

  • Consider daylight at the design stage - roof windows will make sure the extended space is filled with natural light
  • Thoroughly research and vet all contractors to make sure they will bring your vision to life. Personal recommendations are gold!
  • Investigate planning permission and building regulations to make sure your plans are compliant

Research contractors

Consider which experts you want to hire for your project. An architect or designer can be a significant cost but their experience and expertise can make all the difference, from advising on construction techniques to knowing how to make the most of the existing space in your home.

Whether you’re appointing an architect, builder or other professional, take your time researching candidates. Get multiple quotes, visit completed projects and speak to previous clients. Ask friends and family for recommendations, and make sure you feel confident in their skill and communication style as you may be working with them for quite a few months.

Think about natural light

It’s important to consider daylight in the design stage of a home extension. A home extension can sometimes cause the light source to be moved further away from the centre of the room, which creates darker areas. Adding roof windows to your extension means the natural light is brought deeper into the space, providing up to two times more light than a vertical window of the same size. Unlike vertical windows, roof windows allow daylight to reach every corner of the room throughout the day as they are not affected by orientation. Think about where you will need the light the most in your extension, such as a roof window over the kitchen to make sure you’ve got great light for cooking.

Investigate planning permission and other obligations

An important step is investigating what planning permission and building regulation standards would apply to your plans. Most extension plans will not require planning permission if they meet certain size, height and boundary limitations and conditions, known as Permitted Development, while others may require a planning application. Different rules also apply for listed properties or if you live in a Conservation Area.

Even if your extension is within Permitted Development, you will need to comply with Building Regulations to ensure the work meets a minimum standard. Additionally, if you share a wall with a neighbour you may need to give them two months' notice under the Party Wall Act. Even if you don’t, have a friendly chat with your neighbours to talk through your plans and help the build process go smoothly.

Check with your local planning office or a planning consultant to get advice for your project.

"A successful home extension starts with a clear vision. You know you need more space, but what do you need that space to do? What problems does the extension need to solve?"

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