Adding an extension to your property is a great way to give yourself more space without having to move house. Two-storey extensions are also quite an economic option; a second storey costs much less to build once the first is already in place, so building your extension might cost a lot less than you'd imagine. As well as adding value to your property, an extension can also help 'future proof' it against changing requirements and, of course, growing families!

When building an extension of this kind, there is no shortcut. You will definitely require planning permission, and a successful application will take into account structural integrity, utilities and so on. You will also need to consider the needs and rights of your neighbours during the design stage. It is also worth considering exactly how much an extension of this kind will add to your property's value. Speak to a local estate agent about similar properties in the area that have undergone extension projects, and see how much of an impact they had.

Planning permission for a two-storey extension

The first thing you will need to know about planning a two-storey extension is that you will definitely, without a doubt, need planning permission. Though specific regulations will vary between different areas in the UK, you will need to make a successful application for your project to go ahead, and this will require the help of several specialists. Firstly, have an architectural designer create proper blueprints for the project and have the project assessed by a structural engineer. The positioning of your property's utilities will also have a large influence, and so if necessary speak to a local electrician or plumber about how they can be altered and made to accommodate your new extension. Of course, there will always be additional considerations if your property is a listed building or if you live in a conservation area.

When you make your application, your neighbours will be alerted by your local planning authority. Your specialists will be able to advise you on boundary restrictions and so on, but there are other considerations that may make your neighbours object to the project. If your new extension blocks or limits their access to natural light, for example, they can complain and potentially have your planning permission overturned. To avoid costly delays, it is best to speak to your neighbours beforehand, or even to hire a party wall surveyor between you.


Two-storey extension design ideas

Think carefully about the position of your new extension. Wherever it is it will have a big impact on your existing property, but there are some specific factors to consider, such as your view, garden access, privacy and windows. You will also need to decide how the additional space will fit into your existing room plan. This should be a focus in your architectural drawings. It may well be that you have to sacrifice parts of your existing rooms to make the new space accessible.

Extensions can have a big impact on your access to natural light. Removing external windows will deprive your inner house of light, and some rooms behind the new extension's walls may be left without natural light altogether. One option is simply to reposition these rooms, or to convert them into rooms that do not require natural light, such as a utility room or WC. Remember, WCs and bathrooms can be repositioned almost anywhere in the house. If you want your new space to add to the old in a more open-room style, there are options to be creative with your lighting. For example, you could have a velux window or skylight installed to provide light from above.


A common issue with extensions of this kind is ceiling height. Depending on the structural support in place, you may end up with lower ceilings than your would like, especially if you end up using a downstand. A solution is to integrate the new rooms into your roof structure or to set the extension slightly lower. Ask your architectural designer or structural engineer early on to see if you will face this issue.

An aspect of planning permission that may end up causing you a great deal of misery is the positioning of your property's utilities. Their positioning will need to factor into your architectural plans and planning application, and it may be that some need to be repositioned before you can build your extension. You don't want to end up with a manhole cover in the middle of your floor!

Another potential issue with utilities is that the building work itself may leave some of yours unconnected for a few days. You could find yourself without a kitchen or running water during some parts of the build, so talk about this prospect with your tradesmen early on. It may be that you will need to arrange temporary accommodation elsewhere.

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