January 20, 2020

How much does a side infill extension cost?

Written by Rebecca Clayton


A cost guide to side infill extensions

Side infill extensions are a great way to open up unused spaces and utilise natural light, often used to complement London Victorian or Georgian style properties. A glass side infill extension can seem costly, however, the common alternative is dark, unused storage areas or completely wasted space. But how much might an addition like this cost?

The starting price for a glass extension of this nature would be approximately £7,000 for a simple glazed link, or for a small glazed area. When considering costs do bear in mind that due to the bespoke nature of glass structures, it is not simple to provide generic estimated costs for glass structures as the costs depend on the design, size, shape of the glazing panels, the project location and various other factors.

It is increasingly popular to incorporate a window or door into the glass structure to open up living spaces and improve access to the rear of the property, particularly those with a garden. Adding a window or door may also allow the property to benefit from the maximum natural light throughout, bridging the gap between indoor and outdoor living. The cost of incorporating a window or door into the structure would vary dependant on models and sizes desired, as a cost guide the glass for this would take the price closer to £12,000.


Glass side infill extension with a vitra pivot glass door


This side infill extension cost £14,000, the project included a window and Vitra pivot to maximise the light and space of a London basement flat.





Glass side extension with Sieger aluminium bifold door


This newly completed side infill project on a London home compromises our bifold door and casement windows, both by Seiger and cost a total of around £10,000.








Terraced Victorian house with back extension featuring a glass pivot door


This early Victorian mid-terrace house featured on Grand Designs ‘Extension Special’ in 2017, cost £16,000 and saw the homeowners incorporate a Vitra pivot within the 12sqm extension.




Modern glass side infill extension with minimal windows sliding glass door and glass overlight



An example of a luxury side infill extension, this double height glazing was £40,000 and featured our minimal windows and structural glass overlight with returning structural glass strip rooflight.







As far as planning permission goes, providing it’s a considered extension at the rear or side of a property, your glass extension shouldn’t require anything different than a regular extension would.

If you are looking for more advice or want to come and visit our showroom to see for yourself, please do make an appointment at the Sky House Design Centre where we will be happy to help.

For further information or a quotation please call the team on 01494 722 880 or email hello@iqglassuk.com.