5 Things to think about when planning an extension

5 Things to think about when planning an extension

People choose to extend their homes for a variety of reasons – to add value, to make it more balanced or to simply give them more space for a growing family. Whatever your reason may be, you still need to make sure that you are properly prepared for the extension and that you have thought through the main considerations before you start. The following list of 5 things to think about before you get started on an extension will ensure that the project gets going without a hitch.

Planning permission

Before you even start you should consider whether your extension will require planning permission. The rules for planning in your area are detailed at the UK Planning Portal website and there, you can find out if your extension will come under permitted development or if you will need to go through the planning process. This could add as much as 3 months to the time it takes to complete your project, but it does ensure that your extension is legal and that your neighbours are aware of what is happening.

Building regulations

This is quite distinct from planning permission and most extensions will require building regulations approval, even if they do not need planning permission. Essentially, buildings regulations ensures that your extension is safe and that it meets the current legislation for the type of work you are having done. It is a simple process and probably won’t slow down the build too much. It usually involves one or two visits from an inspector to ensure the work is being carried out to their rules and regulations.


Before you do any work at all you should check with your buildings insurer to find out what their rules are when it comes to building work. Most builders will have the necessary site insurance, but don’t take their word for it. Ask to see their certificates and and get your own insurance if you are not sure. If you are leaving your home during the work you need a special type of insurance to cover this.

Permitted development

Under the current planning rules, extensions of under a certain size do not need permission before the work is undertaken – but there are some caveats that you should be aware of. If your home is in a conservation area or is listed (either grade one or two) you should check with your local planning department to see what is allowed for your home. There are also recommendations about the sizes of certain rooms and if you decide to go smaller to accommodate the permitted development rules you may fall foul of the planning rules.

The Party Wall Act

If you have neighbours who share a wall with you and you are doing work that comes within 3m of their boundary or you are digging foundations within 6m, you need to make an agreement with them. This is not covered by either planning permission or building regulations. Usually a surveyor will be able to arrange the Party Wall agreement for you. Your neighbours cannot stop the work going ahead, but in law you need to inform them.

These five things to think about may be covered by your builder (who should know all the rules) but it makes sense to understand the processes before you start.