Single storey extensions are a fantastic way to change up your home’s layout and add extra space; yet they’re often overlooked in favour of large multi-floor extensions or full house moves, despite them being considerably easier to manage. That said, there is lots of planning to be done for single storey extensions – and here we give you the lowdown on where to start with yours.

The start of a single storey extension

Budgeting For A Single Storey Extension

Although single storey extensions are usually much cheaper than multi-level extensions or full house moves, they still form a considerable investment as they convert the design of your property and so a budget needs to be effectively set before work begins.

A single storey extension can be built for less than £2,000/m² for a basic quality build; so about £30,000 for a 4m x 5m space. For standard quality, prices range up to £2,200/m² and for a high spec build, up to £2,500/m².

On top of these basic build costs, there are further fees to add on. Architect’s fees work out around 5% of the total project cost, and a structural engineer will cost about £1,000 if required (for roof joists and foundations, if these are to be included). A survey will cost up to £1,500 (provider and size dependent), and a professional project manager can be hired to oversee the works for around 7% of the total project cost. VAT is payable at 20% the cost of labour, materials and services. In the UK, planning fees add up to around £250. Building control charges are dependent on the size of the project up to £900, and if a party wall agreement is required this costs around £1,000 per neighbour.

Additional fees that are required in some circumstances include tree reports, flood risk assessments, archaeological reports, historic buildings reports and interior fit-out costs.

Interior Fit Out Costs

Once a budget has been set for the build, interior design costs need to be considered. The exact cost involved depends on the type of room you’re installing, but as a ballpark figure:

Kitchens cost between £5,000 - £30,000 dependent on size and spec

Bathrooms cost between £4,500 - £11,00 dependent on size and spec

Flooring costs between £25 - £100/m²

Plaster and drylining costs around £85/m²

Sliding and bifold doors cost around £1,500 - £2,000/linear metre

Extending existing central heating systems will cost labour and materials, with underfloor heating options being more expensive to install. A new boiler, if required, can cost around £3,000.

A single storey extension from outside

Planning Permission Requirements

Planning permission regulations vary dependent on location and local authority, but usually, formal permission for a single storey extension will be required when:

It covers more than half the area of land surrounding the property

It extends out toward a road

It increases the overall height of the building or is over 4m tall

It extends more than 6m from the rear of an attached house or 8m from a detached house

It is more than half the width of the property

It includes a balcony.

Your Refresh Renovations specialist will be familiar with local regulations and will be able to advise you further. In some cases, permitted development rights (PD) may be granted which will negate the need for full planning permission.

All single storey extensions must comply with building regulations. All local authorities require an application of works to be filed before the project can begin.

Party Wall Arrangements

If a wall on the extension sits directly on a boundary with another property, you will need a party wall agreement with your neighbours. This can be arranged directly with your neighbours and they are entitled to hire their own surveyor (at your cost) if they would like further information on how the single storey extension may affect their property value.

A CGI of a extension

Designing a Single Storey Extension

A single storey extension can be designed either by a homeowner in conjunction with a builder or by an architect, and will to some extent be dictated by planning permission and local development rules. The design must carefully consider the integration of the new space with the existing property.

The position, size and shape of doors and windows can transform the light through a living space as well as shift the views from the property; all of which can really change the feel and features of a property. The style and framing of the new space must complement the existing design features of the home to enhance it rather than focus away from it, and should create a natural flow through the home.

There are lots of ‘tips and tricks’ in the building industry to help seamlessly install a single storey extension in to a property. Consider installing a wider than usual doorway into the extension (or none at all!), hiding joists in the ceiling void to ensure a continuous ceiling levels, matching up floor levels and continuing decorative elements through in to the new space. Accessibility considerations should not be forgotten.

Although you may wish to conceal your extension to your property so it looks natural and as though it’s always been there, a contrast in style can lend an impressive modern aesthetic; ideal if perhaps covering it up would be tricky. The taller the ceiling and the greater the light levels, the bigger the new single storey extension will feel, but if low pitch is the only available option for development, creative roof design can be factored in.

The possibilities are endless with single storey extensions. Creative, clever design is key: and if done right, your whole home can be transformed. Don’t be afraid to pay a little extra to work with an expert who can help you get it right first time – after all, if you’re in it for the long haul, this extension could enhance your quality of life within the property for many years to come. 

Here at Refresh Renovations our end to end process supports a bespoke design and build: a renovation tailored to your lifestyle requirements and taste. Your local renovation specialist will manage every aspect of the single storey extension for you - working to keep everything on track, including your budget.

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Ready to chat about your single storey extension ideas? Get in touch to arrange a free, no-obligation consultation with one of our renovation specialists.

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