An extension is a great way to make your home bigger and better, as long as you don’t make your garden too small in the process.

While building an extension will cost tens of thousands of pounds and take many weeks, it’s often a more attractive option than having to move home when you’ve outgrown your current one.

Depending on your home’s layout and as long as the new layout complies with building regulations, a single-storey extension can be turned into pretty much any sort of room or rooms, typically a kitchen-diner, especially in a side return, but also an extra living area, a den, a home office or even a ground-floor bedroom and en suite, perfect as a granny or nanny annex.

If you can run to a two-storey extension, you’ll be able to increase both your living and sleeping space, or add a dressing room or extra bathroom upstairs, whatever you need.

Instead of applying for planning permission, the easiest option is to make use of your home’s permitted development rights. If it doesn’t have these rights, or you want an extension that can’t be done under permitted development, you’ll have to go through the planning process, which can be lengthy, expensive and frustrating.

To be done under permitted development, your extension must conform to certain conditions. You’ll find full details at www.planningportal.gov.uk (the information applies to houses, not flats, maisonettes or other buildings), but one of the main conditions is that extensions and other buildings shouldn’t account for more than 50% of the land around the original house.

There are also constraints on the width and height of extensions. For example, the width of a side extension mustn’t be more than half the width of the original house.

There are different rules for single and two-storey extensions and for rear and side ones (for example, side extensions on ‘designated land’, which includes conservation areas, are not permitted development), so it can be quite complicated.

The only way to be sure which rules apply to your home is to ask your local council.

You should also check the terms of the lease if your home’s leasehold, because you may need the permission of the freeholder to carry out a major alteration like an extension.

If the extension will be along a shared boundary with a neighbour, you’ll need a party wall agreement with them to comply with the Party Wall Act, which, again, can be a long, expensive and frustrating process if there’s any dispute.

As well as special conditions for designated land, there are different rules for listed buildings. If you live in one of these, you’ll have to apply for listed building consent from your local council before building an extension.

The council’s building control department will need to inspect your extension (for which they’ll charge a set fee) as it’s built, to ensure that it complies with building regulations.

You’ll also need a completion certificate from them when the work’s done, which the buyer’s solicitor may ask for when you sell your home.

While you might want to decorate your extension yourself, you probably won’t want to build it.

You could get an architect to design it and then a builder to construct it, or get the architect to manage the project (they’ll usually charge a percentage of the build cost for doing this) and the contractors. They’ll have tradespeople that they regularly use, so you’ll (hopefully) have less to do and worry about.

As well as time to build the shell, you’ll need to factor in fitting-out time. A kitchen will take longer than other rooms and will also, of course, be more expensive.

Like any other big home-improvement project, an extension can easily go over budget, so keep a careful eye on the numbers and always have a contingency fund for unexpected problems.

Product of the week

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If you’re holding a street or garden party over the long weekend, this is the perfect tape for putting up bunting and flags. It can even become part of the display – use it to turn plain table and garden decorations into jubilee-themed ones.

Union Jack Duck Tape costs from £5.99. Call 01442 275 311 for stockists.

How-to tip

If you’re painting white on white, make things easier for yourself by using paint that goes on pink but dries white, so you can see which bits you’ve done and which you haven’t.

Try Dulux Magic White Silk Emulsion Paint, £16.98 for 2.5ltr, BQ.