The Sterlingbuild Guide to Single Storey Extensions

Single storey extensions are by far the most popular choice among homeowners when it comes to extending a property.

Here are the important things you'll need to consider, from planning permission and building regulations to Sterlingbuild's recommendations of the best products to bring your new space to life.

Why you should build a single storey extension

When all the costs of upscaling and upheaval are considered, it is understandable that more and more people are choosing to stay put and extend their existing properties, often saving time and money in the process.

Single storey extensions, most often in the form of a rear extension or side extension, are a great way of gaining more space for the family, with open-plan living and rooms that better connect home and garden increasingly popular.

As well as more space, a single storey extension also provides the opportunity to allow more natural light into the home, creating a brighter and healthier space.

VELUX flat roof windows for single storey extension
aluminium bi-folding doors for single storey extension or kitchen extension

Single storey extension ideas

Whether your single storey extension is flat roofed or pitched, in order to create a living environment which is light and welcoming for friends and family, the right rooflights or pitched roof windows can make the world of difference, allowing three times as much daylight into a room than vertical windows.

For flat roof extensions, rooflights from ECO+ are the one of the most thermally efficient on the market and come with a pre-built upstand as standard. Also consider UK-made Signature rooflights for greater variety and sleek design.

ECO+ also manufacture pitched roof windows with triple glazing as standard for superior insulation. Contemporary, energy efficient roof windows are also available from RoofLITE and sister companyVELUX, in manual and electric.

Popular open-plan layouts that involve extending the living or dining room out towards the garden are tailor-made for the installation of REAL aluminium doors, available in sliding and Bifolding designs.

Pitched roof or flat roof?

The type of roof that you choose will define the overall look of your extension.

Flat roofs are generally cheaper than pitched roofs, as there is likely to be less building work involved. Flat roof extensions also offer greater flexibility on what you can do with your roof, such as incorporating a Korniche roof lantern 

Pitched roofs, on the other hand, allow for a bigger overall space as the ceiling can be higher underneath and the appearance of the roof is known to blend in more effortlessly with the existing building. 

If you need to work out the pitch of your current roof for the purpose of building an extension, read our blog 'How Do I Work Out My Roof Pitch?'

VELUX pitched roof windows with pine finish for single storey extension
VELUX white velux windows for pitched roof and single storey extensions

How much does a single storey extension cost?

The cost of a single storey extension will depend on the scale of your project and where abouts you live in the country.

A basic extension will typically cost you around £1,000 per square metre, meaning a 3 x 5 metre single storey extension, for example, would set you back £15,000.

While the bulk of outgoings will go on building materials and features, approximately 10% or 15% of your budget is likely to spent on professional fees such as an architect and building regulations. 

To save on the overall cost of your materials and shipping, you can purchase the complete home extension package at a discount with Sterlingbuild, including flat roofing systems like EPDM and GRP. Read our GRP V EPDM blog to find out which is better for your budget and requirements.

Important things to consider

Planning permission for extensions is first thing to think about, whether you think you need it or not. The Planning Portal can provide a full picture on the limits and conditions to your conversion.

If objections are received to your expansion by neighbours, a Neighbour Consultation Scheme will take place to see if you can proceed with your home improvements.

You will also need to consider the Party Wall Act that covers the construction of a new building on or at the boundary of two properties. It is therefore worth informing your neighbours of your plans before the council does- their early approval could save you a lot of money!

Contact a ‘building control body’ (BCB) to check a full list of building regulations appropriate to your property. This can be done via

Visit our Loft Conversion Guide for guidance on who can help with your extension.

VELUX flat rooflights for home extensions