Adding a glass box extension

Q: We want to create a glass box at the back of our house. Could you advise us on the best way to do this, and what we should consider?


A: This sounds like a very exciting but aesthetically challenging project. Your choices will be driven by the standard and quality of design that you’re looking for, and how much you’re willing to spend on your new addition. If you’d like an extension that seems to have no visible structural supports, it will need glass beams and posts rather than metal. This level of frameless technology is obviously the most expensive, but if it’s done properly it can be worth every penny – for examples of structural glass systems see IQ Glass (01494 722 880; or GlasSpace (0845 230 9569;

With this type of development you will always be weighing up how visually sleek and light you want the structure to be against your budget; steel frames can be more expensive than aluminium, but the benefit is that the post and beam supports can be slimmer. Cantifix (020 8003 3509; is one of the best glazing specialists in the UK, and offers fantastic framed and frameless options.

I would recommend choosing double or triple-glazed panes; you can even opt for heated glass, so your extension acts like a big radiator. It needs to be designed with thermal performance in mind to prevent overheating in summer and coldness in winter, and you may need to consider installing blinds to avoid glare. For self-cleaning glass, check out Pilkington (01744 692 000; – it’s a great option if you want a low-maintenance solution.

This excerpt was taken from Grand Designs Magazine click here to see the latest offers.