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Building

Expert advice on structural work, home extensions, renovations and understanding building regulations.

Building

Home Extensions: A Comprehensive Guide

As your needs change, it can be easy to start looking at property sites and dreaming of a new home. Whether you dream of going bigger, smaller, more modern, more period, or you just want a change, there are plenty of properties out there with amazing specifications and, often, price tags to match. Moving home doesn’t just involve the upheaval of packing and unpacking your life; stamp duty, legal fees and other costs can make it prohibitively expensive.

As your needs change, it can be easy to start looking at property sites and dreaming of a new home. Whether you dream of going bigger, smaller, more modern, more period, or you just want a change, there are plenty of properties out there with amazing specifications and, often, price tags to match. Moving home doesn’t just involve the upheaval of packing and unpacking your life; stamp duty, legal fees and other costs can make it prohibitively expensive.

When it comes to making your home work for your ever-changing family and growing needs, as well as optimising your property’s value, extensions may be a wiser choice than moving home. In this series we talk through everything you need to know, from thinking about extensions to choosing the right architect and builder.

Consider your options

When considering an extension, there are a range of routes that you can go.

Out: making your kitchen or downstairs living area bigger, or adding an accessible downstairs bedroom or bathroom.

Into your garage: If you have a garage that could be better used as a snug, bedroom, office space or utility area, this can be a relatively cheap and paperwork-free option.

Up: attic space can offer much more value as an additional bedroom or office rather than the traditional storage area.

Out and up: if you have the footprint and the budget, a double extension could completely transform your home, adding additional space upstairs and downstairs.

Things to consider

The main motivation for building an extension is to improve the space for you and your growing (or shrinking) family. However, it is important to consider resale, too; few homeowners have disposable cash that they are happy to lose money on an extension. Before you decide what to do to your home, take a good look at property sites and see how much homes similar to yours are, and how much more extended properties are marketed for. You can also get in touch with a local estate agent to provide a valuation for your property now and once extended. The agent may even be able to advise you on the most sought-after extensions, to help you to make sure that you invest your money wisely.

Property prices in your area are likely to be capped; check with the agent what the current upper limit is likely to be, as this can help you to determine your budget. Once you know roughly what you want to do and what budget you are likely to want to work with, you need to look at permissions to make sure that you are going to be able to do the work that you want to do.

Follow us on Facebook or X for the next instalment, where we talk about building regulations and planning permission.

Looking for more building advice?

Find clear, practical answers to common building questions, helping homeowners understand everyday issues, know what checks they can carry out safely, and when it is best to contact a qualified professional.

  • Do I need planning permission for a home extension?

    Plenty of extensions don't need planning permission - they fall under Permitted Development. Whether yours qualifies depends on the size, location, and type of build. Single-storey rear extensions up to four metres on a detached house often get the green light, but side extensions, two-storey builds, and properties in conservation areas usually do need permission. Always check with your local planning authority before you start - building without the right approvals can mean being made to undo it all.

  • What is involved in building a conservatory?

    You're looking at groundworks and foundations, the frame and glazing, the roof, and then the internal fit-out - flooring, heating, electrics. Most conservatories under a certain size fall under Permitted Development, but they still need to comply with Building Regulations, especially if you want to use the space as a proper room year-round. On the roof: solid or tiled options make a huge difference to usability - traditional polycarbonate can be unbearably hot in summer and freezing in winter. Most projects take two to six weeks.

  • Do I need a structural engineer for my home renovation?

    Not for everything - but if structural changes are involved, yes. Removing a load-bearing wall, putting in a steel beam, touching the roof structure, or adding a sizeable extension all need a structural engineer to design the solution and produce the calculations for Building Regulations approval. A builder might tell you whether a wall is load-bearing, but only a structural engineer can specify the right beam and carry professional liability for that advice.

  • Do I need planning permission to install patio doors?

    Usually not, if you're replacing an existing door or window in the same opening - that typically falls under Permitted Development. But if you're making the opening larger or creating a new one in an external wall, you may need planning permission or Building Regulations approval. Conservation areas, listed buildings, and properties with an Article 4 Direction have tighter rules, so check before assuming. Any structural work to the opening, like fitting a new lintel, needs Building Regs sign-off regardless.

  • Does my extension need Building Regulations approval even without planning permission?

    Almost always, yes. Planning permission and Building Regulations are two separate things. Extensions need to meet regulations covering structural integrity, fire safety, insulation, ventilation, and drainage - regardless of whether you needed planning approval. Your local authority's building control team can confirm exactly what's required. And don't skip it - missing Building Regs sign-off can cause real headaches when you come to sell.

  • How long does a typical home extension take?

    A small single-storey extension usually takes eight to twelve weeks from groundworks to completion. Add several months if planning permission is needed before work can even begin. Bigger builds - two-storey additions or anything needing significant structural work - can take four to six months or more. Get a realistic timeline from your builder upfront, and factor in a buffer for the unexpected.

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