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31st March, 2023

A Basic Guide to Frameless Glass & Glass Box Extensions

Frameless structural glass is an extremely popular design material used to create contemporary structures, enclose balconies and staircases, open solid walls to the outside and even feature flooring. The sleek lines and minimalist nature of the glass creates an ultra-contemporary look that many homeowners are striving to achieve to create a home that is unique and modern with a real wow-factor finish.

If you are considering adding a frameless glass box structure or a frameless glass design feature, our mini-guide will give you a good overview of the basics.

A Basic Guide to Frameless Glass


The great thing about frameless glass is its versatility. It lends itself to multiple uses and can work for a large all-glass extension, a small side return extension or as a simple roof light to open up a roof and bring in more light. The design using frameless glass is clean and non-fussy as well as not imposing any specific aesthetic on the original building. You may be surprised to know that frameless glass extensions are a popular choice on older and listed properties due to the blank canvas that the glass offers. It adds style while allowing you to still see the fabric of the original building. There are endless options for the shape of a glass extension, including lean-to, gable-ended, hexagon, or a box.

Frameless Glass Roof Top Room


You may wonder if you need an architect to design your glass space.  The answer is no, not necessarily. If you pick the right company for your build they will be able to draw up plans for your bespoke structure.  If you want something more complex, an architect could be a worthwhile investment, especially if you need to gain planning permission.

Planning Permission

When it comes to planning permission in general the same rules apply to a framed glass structure. The majority of glass box extensions can be built under permitted development rules.  This means that most small to medium structures won’t need planning permission at all as long as you haven’t already extended your home which may take you over the limits set with permitted development. If your home is listed or in a conservation area, you will still need to get planning permission as with any structure. Before embarking on any project, you should still consult with your local planning authority to ensure your structure is designed within the realms of permitted development before going ahead.

Lean-to frameless glass link extension
glass balcony balustrade on a luxury country home

Energy Efficiency

Glass box extensions offer the gold standard in energy performance. The high-performance glass combines low e-coatings, uv filtering as well as argon gas filled creating a highly insulated building material. Each company will have their own specification of glass, but with the fact that by its nature a frameless glass structure has more glass than solid frames, you must invest in the most efficient glass you can afford. A superior temperature and UV-controlled glass will command a premium price but will be the difference between you being able to use your room year-round or not. With stricter rulings having been introduced in the guidance of Over Heating in homes due to global warming, it is more important than ever that glass construction is efficient in order to meet the standards.


The glass used to create an all-glass structure offers a high level of durability. It has to be tough enough to match other building materials, but also have the crystal-clear clarity of double glazing. The structural glass extensions are made from a specialist dense toughened glass that meets Class A of BS6206; the glass roofs are strong enough to be walked on!

Glass Rooms

All glass rooms make a real statement and are truly the epitome of style and truly living that indoor/outdoor lifestyle.  Glass rooms are full of light and remove the visual barrier between you and the outdoors. Adding in bi-fold or double doors will further connect the space with your garden and creates a free-flowing entertaining space for the warmer months. A glass room can be hugely versatile offering multiple options for functionality including a room to relax, for dining, to get creative, workout or even as a multipurpose room such as a kitchen/dining/living space.

Glass Wall

Even if you are not looking to extend the footprint of your home, structural glass could change the design of your home by replacing the external wall and the roof with glass. Again this will bring in lots of natural light and make the space you have feel so much larger without even extending.

A frameless glass box extension floods light into the property and extends the living space out into the garden


If you want to make a design statement on a smaller scale, glass balustrades on your staircase and landing will add a contemporary touch. As well as serving a practical function, the glass will also keep what can be a much darker and enclosed space open and light.

Glass Floor

If you want to create a feature on a roof terrace or perhaps lighten an entrance hall, a great way to do it would be to use structural glass as part of the floor. It can help to bring light into an otherwise space and make it feel more open.

Roof Lights

Roof lights are popular to use in areas such as kitchen extensions to again lighten a space and add a focal point.  In a similar way to an orangery, they work well with a slatted roof and can be added with an apex design to add drama.

Frameless glass roof terrace extension


You can complete your glass extension with doors out to the garden. There are completely frameless French fold-back door options, as well as fine framed sliding doors and even bi-fold options.

Design your frameless glass project

Why not start discussing your project with our frameless glass specialist to get an idea of the options right for you and your property and get a better idea of costs? You can also check out some of our customer’s projects for inspiration in the gallery.

Start designing you frameless glass project

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