How much does a glass extension cost?

Cost is a key consideration for any home improvement project and if your heart is set on a glass extension you will no doubt be wondering what kind of budget you'll need.

While any kind of extension to your home will create more room and open up your living space, designing it in glass will take it to another level. Unlike a brick extension or a traditional conservatory or orangery, glass extensions have fully glazed roof and walls. This allows natural light to flood your home and blurs the boundaries between the indoors and out in a way that no other extension can. Even a small fully glazed extension can make a huge difference to your living space. You’ll be amazed at how much it opens up and brightens your room.

And a glass extension can look truly stunning indeed. It’s also an extremely flexible option aesthetically, whether you’d like it to complement your home – whether it’s a modern or period property – or alternatively provide a stunning contrast to the original building. Glass extensions are custom made to your specifications so you can be as free with the design as you like.

A glass extension can therefore be a fantastic investment that adds value to your home and can be enjoyed for a lifetime. But how much will it cost to add one to your home? Our guide will help give you an idea of how much your glass extension will cost.

Glass extension cost

A glass extension will generally be more expensive than a brick extension or a traditional conservatory or orangery. As with all building work, the cost will depend on the size of your space, the complexity of the design and the materials you use. Larger glass panels may require specialist machinery to be lifted in to place, while additional features such as smart systems can also bump up the price.

As a general rule of thumb, a glass extension is likely to cost from £3,500 plus VAT per square metre¹, although this can vary hugely because of the bespoke nature of each structure. And it's worth bearing in mind that economies of scale mean the smaller the structure, the more expensive it is per square metre.

The key is to choose a reputable specialist designer, manufacturer and installer of glass extensions who will offer you a high level of service and expertise that will ensure the very best result for your investment, however much it is.

The average cost of a glass extension

With glass extensions starting from £3,500 plus VAT per square metre¹ for the glass alone, the total cost is largely dependent on how big it is. If you can afford it, the sky is the limit when it comes to cost and features.

However, if we take as a UK average a good-sized glass extension measuring 4.8 metres by 3.5 metres (16.8 metres squared), then we would work out the average cost of a glass extension to be from £50,000 plus VAT.

Other factors affecting cost

When calculating the cost of your glass extension, there are a variety of other factors to take into consideration.

• Hiring professionals can comprise around a third of the total cost of a glass extension project. It will involve various architectural, construction and design professionals such as an architect, structural engineer and specialist glazing installer.
• Groundworks and pre-construction are a necessary part of adding a glass extension.  This will include the laying of foundations, and may also involve underpinning and damp proofing work.
• The installation of large glazed panels is a specialist job that can be time consuming and more labour intensive. It may require a team of people as well as the use of special equipment. This will be reflected in the overall cost of your extension.
• The materials used in glass extensions tend to be of an extremely high quality because this is a premium product.
• Glazing options such as solar control coatings or heat insulated glass will cost more than standard glazing. The same goes for double or triple glazing. However, bear in mind that they may be more cost-effective in the long run because of their increased energy efficiency.
• Additional features such as ventilation, heating and shading options will also add to the price.
• The type of openings you choose for your glass extension will also affect the overall cost. There are a range of opening options, from fixed or tilt and turn windows to bi-folds, sliding doors and even oversized sliding doors, all of which will come in at different prices.
• The costs of surveys and reports should also be factored in to your budget. However, glass extensions generally do not require planning permission (see our article Do you need planning permission for a glass extension? for details).
• Don’t forget to plan in all the other costs involved in any kind of extension, such as flooring, fixtures and fittings. And if you are planning to use your glass extension as a kitchen, you will also have to consider the cost of all the units and appliances.

Establishing your budget

It’s important to establish your budget before beginning work on your home. Make sure to get a quote from a reputable specialist manufacturer and installer of glass extensions to give you an idea of how much your planned project will cost.

To help you establish your budget, our team of glazing experts can give you an honest and realistic guide to what's possible within your budget. We can provide 3D illustrative images of your proposed Wintergarden glass extension. These images are for illustration purposes only and should not be used for reference or building work, but they help to bring your ideas to life and envisage the extension within its surroundings.

We will work closely with you and your other contractors every step of the way, from concept and design right through to installation and aftercare. We provide a budget proposal followed by a detailed quotation, site survey and manufacturing sign off drawings where applicable. All prices and specifications are subject to a site survey.

As a specialist glazing company our services do not include architectural works, planning, building control, structural engineering, foundation works, builders’ works, electrical works or finishes.

¹ Correct as of August 2023 and subject to change

This article was originally published in May 2022 and updated in August 2023 to correctly reflect the cost of a glass extension.