Two thirds of homeowners are opting for a single-storey designs when extending their home, research* can reveal. But are they missing out on maximising their property’s potential?

A total of 66% of prospective extenders said that they were building a one-storey addition, while 34% (4,552) were opting for two or more storeys.

Cost will undoubtedly play a part in the decision on what size extension to build, but homeowners may be labouring under the miscomprehension that building a two-storey extension will cost twice as much as a single-storey addition. 

In fact, a single-storey extension will have the same foundation and roofing costs as a two-storey alternative, meaning your extra cost, in terms of structure, will come in the form of building up the second storey walls and any additional glazing. While your costs may be slightly more overall, the price per square meter will be lower for a two-storey extension and the additional cost can often be recouped back in the value it can add to your property. 

The Storey So Far

While it can prove a false economy to build a much bigger extension than you need, it is definitely worth consulting an experienced architect or designer in order to consider all of your  options at the design stage. A design expert could also help you consider the impact an extension will have on the rest of the house, and help you add considerable value to your property.

Another reason homeowners may be opting for a single-storey extension over a double-storey one is the issue of planning permission. Single-storey extensions, if they fall within certain parameters in terms of size and their location, can be classed as Permitted Development. This avoids the need for, and the associated cost and potential delay to the project, of securing planning permission from your local authority.

Earlier this year, in a bid to make it easier for renovators and extenders to expand their homes upwards, the government announced its intention to waive planning permission on two-storey extensions.

However, no formal documentation has laid out how the plan will be rolled out and it is currently unclear how this will be implemented. 

*These statistics are based on more than 13,000 people who used Homebuilding & Renovating’s Extension Cost Calculator.

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