How to build a single storey extension

Building a single storey extension takes meticulous planning and preparation, but where do you start? This article will help answer the most common questions regarding single storey extensions.

How much value does a single storey extension add?

Adding a single storey extension to a house can see its value increase between 5-15%. This depends on the quality of the extension & what you do with the extra space, master bedrooms typically increase the value of the property more than bathrooms or office space.

For more information about adding a bathroom to your house, be sure to check out our articles about bathroom loft conversions & 11 attic bathroom ideas for your loft conversion.

How long does a single storey extension take to build?

Single storey extensions normally take between 3-4 months to complete if no delays occur. Issues may arise which extend the length of the building process, such as building materials not arriving, or illness among contractors.

How much does a single storey extension cost?

A single storey extension costs an average of £35,000. Most contractors charge per m². For example, typical costs are around £1,000 – £1,500 per m².

Additional costs

There are also many additional costs that you will have to take into account before you begin planning your dream single storey extension.

Architect Plans

After you have decided that you would like to go ahead with your single storey extension, you can help your plans come to life by commissioning an architect to draw up your plans professionally.

This process can cost 5 - 12% of the entire extension, but is a great document to show your contractors to ensure you get everything how you want it - from the doorways to the roof windows.

Building regulations

Obtaining the rights to build on a property can be fairly stressful without the thought of having to pay for the overall process. As the building regulations requires copious amounts of paperwork and in-person visits, the price of having your property certified can reach £1,000.

Prices do differ based on the size of the project or the location of your property.

Removing old necessities

Building on top of an existing property will always come with its challenges, and some hidden costs can come from removing old necessities.

Items such as wiring, drains and boilers may all have to be removed and reinstalled if the new extension interferes with any of their inner workings.

Site survey

Having your property surveyed before any work has been completed is a great way to prepare you for any challenges that may arise in the future, whilst also saving you money in the future.

Surveys can allow you to have a much deeper, detailed look at your property and give you a list of issues that may already exist before starting your project.

These surveys start from £500, but rise the larger your home is.

Laws & Regulations around extensions

Party Wall agreement

The Party Wall etc. Act 1996 states that if you are sharing a wall with somebody else, perhaps a neighbour, you must notify them that any building work is taking place between 2 months and a year before the work takes place.

After explaining the work about to take place, you can then give your neighbour a written notice of said work.

Here you can find examples of party wall booklets.

Building regulations

Any extension work conducted on a property that is above ground level will always need building regulation approval, and it is recommended that you get approval before any money is invested into the project.

Fees regarding building regulation approval differentiate from council to council, so we advise checking your council’s website.

Planning permission

Before any work begins, you should ensure that you have planning permission for your project. Building your extension with obtaining planning permission from your local authority may result in them demanding you to redo all of your changes.

You can begin your planning permission process today.

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