Glass has a significant role in the infrastructure of a building, providing light, protection, energy, and safety. Glazing is the installation of glass in windows and doors. It’s a major way to stop heat loss in your home, keep unwanted sound out, and save on your monthly energy bills.

In this guide, we’ll cover the types of glazing available, explore queries around installation and longevity, and explain the glazing services available at Stanmore.

What types of glazing are there?

Single glazing.

A single glazed window has one pane of glass. Thickness can vary from 3mm to 10mm. It’s rare for properties to have single glazing today, unless they are historic buildings or in need of renovation.

Single glazing isn’t very energy efficient, which means you spend more money on energy bills, and it can also result in condensation inside windows. Condensation happens when warm air comes into contact with a colder surface. It’s a sign of poor ventilation and insulation, and can cause peeling paint, mould, mildew and rot.

However, single glazing can still be used for greenhouses, or in interior doors, without any problems.

Double glazing.

A double glazed window has two panes of glass. They are separated by a vacuum filled with insulating gas, a barrier that provides insulation. Together, the panes and gas are known as an insulated glass unit (IGU). If replacing single glazing, double glazing saves up to £95 per year and 405kg of carbon dioxide.

Triple glazing.

A triple glazed window has three panes of glass. They are separated by argon gas and provide an extra insulation barrier compared to double glazing.

There are also different types of glass.

  • Annealed glass. Standard glass. Resistant to shattering, but can split into large, dangerous shards if broken, which means it’s become less popular over time. 
  • Fire-protection glass. The breaking point of the glass is increased to over 800℃ by adding a layer of hard resin between the panels. 
  • Frosted glass. Diffuses rays of light, blurring the images behind it. Can be created in two ways: by sandblasting using high-velocity grit, or by acid-etching, which uses hydrofluoric acid to erode the top level of glass.
  • Laminated glass. The gaps between panes of annealed glass are filled with layers of polymeric material. This holds them together even if they break, making them safer and more secure.
  • Low-emissivity glass. Reflects more heat than standard glass by using a thin, low-emissivity coating, with light still able to filter through. Passive low-emissivity glass improves insulation during winter, while solar low-emissivity glass keeps heat out in summer. Double glazed versions can do both.  
  • Mirrored glass. A metal coating is added to the glass and sealed with another layer. As it reflects heat rather than absorbing it, it’s used more for decorative purposes.
  • Noise-control glass. A layer of plastic is added to the external window pane. This plastic can dampen acoustics by absorbing sound waves (the extra thickness helps too). 
  • Patterned glass. Annealed glass is heated and passed through rollers which have a patterned mould on them. It’s used more for decorative purposes inside a home.
  • Self-cleaning glass. Has a chemical coating which uses sunlight to break down dirt, which is then washed away when it rains.
  • Tempered glass. Annealed glass that’s been treated with another stage of heating, making it more resistant to breaking. If it does break, the fragments are much smaller and therefore safer.

Double glazing

Double glazing works by using the space between two panes of glass to reduce heat loss. This space creates an air gap wherein air can’t circulate, which slows down the movement of heat from inside your home to outside, improving insulation and saving energy.

Sometimes argon gas is used in the gap instead of air. Argon gas is inert, which means it’s not prone to unwanted chemical reactions. It is denser than air, slowing the movement of heat down even further so your home stays warm.

Different types of double glazed windows

As well as different types of glass, there’s a variety of window frame styles and materials to choose from. We explain them below.

Bay windows

Bay windows protrude from a property, with the standard three or more windows letting in more light from different directions. 

Casement windows

Casement windows are attached to the frame with hinges to one side, allowing them to open. They can open towards you or away from you.

Sash windows

Sash windows open by sliding a pane up or down. Sometimes one pane moves, and sometimes both are able to. More recent sash window designs keep the traditional charm of older styles, but use modern technology to improve energy efficiency.

Tilt-and-turn windows

These are casement windows with an added tilt-and-turn hinge. How far they can be tilted open depends on the design. Some will offer catches so you have a choice in how far to open the window.

Materials available


Both strong and light, aluminium is a great option for newer properties thanks to its modern look.


UPVC stands for unplasticised polyvinyl chloride. It’s the most common material for window frames, due to being durable, energy-efficient and less expensive than other options.


As a renewable resource, wood is the most environmentally friendly option, although it does need more maintenance than other window frame materials. It’s ideal for older properties, as it has more of a traditional look.

What are the benefits of double glazing?

As well as providing better insulation for your home, double glazing has a long lifespan – 20 years if it’s exposed to extreme weather, and 25-30 years if not. Some double glazing can last 30+ years if it’s fitted in a sheltered area of a property.

Research shows double glazing can also add value to your home by up to 10%, if you don’t already have it, or if it needs replacing. Not only will it improve energy efficiency and therefore comfort for you, but prospective buyers will look for it if you ever decide to sell.

How can I tell how old my windows are?

Windows installed after April 2002 should be registered with FENSA to show they meet all the necessary requirements, and the owners should be given a certificate. FENSA stores all past certificates in a database, so you can order a certificate if you don’t have one.

Alternatively, you can check with your local council. They’ll have an online database showing which windows have local authority Building Control approval.

Replacing double glazing

You can test whether your double glazing needs replacing by taking the following steps.

  1. Look at the windows and window frames, both on the inside and outside of your home. Check for gaps and any broken sealing.
  2. Run your hand along the edge of your windows to see if you feel a draught.
  3. Trap a piece of paper in your window, then try to pull it out while the window is completely shut. Ideally the paper will rip – if it doesn’t then you’ve identified a gap where air can get in.
  4. Move blinds, curtains, and anything else that could catch fire away from the windows. Light a candle, then hold it still near the closed window and watch the flame. It will move if there’s a draught coming in.

Other signs your double glazing needs replacing include chips or cracks in the glass, condensation, and leaks.

How much does double glazing cost?

The cost of double glazing depends on a number of factors:

  • How many windows you need to replace
  • The kind of property you live in and how accessible it is for traders
  • The size of the window
  • The style of the window
  • The material used for the frame

According to Household Quotes, average prices for double glazing are as follows:

  • Between £1,550 and £2,750 to replace the windows in an apartment
  • Between £4,900 and £7,600 to replace the windows in a small detached house or large semi-detached house

Triple glazing

Triple glazing uses the space between three panes of glass to reduce heat loss. It works in the same way as double glazing, but the extra pane of glass slows the movement of heat down even further. It’s becoming more commonplace, both in the UK and elsewhere, such as in Scandinavian countries where the climate is colder.

Is triple glazing worth it?

Triple glazing is best for homes which are being built or need old glazing to be replaced, as future regulations are likely to require properties to have better energy ratings. It’s also worth investing in for homes in cold climates, or to tackle specific cold spots in an otherwise warm home. Otherwise, energy efficiency payback is similar for double and triple glazing, so your money may be better spent elsewhere.

You can expect to pay more for triple glazing. For example, if a double glazed window costs £350, the same size of triple glazed window would be around £500. However, the cost of triple glazing will vary depending on the size of your property, the size of the windows, the type of frames you want, and your location in the UK. 

Energy ratings explained

All windows are given an energy rating. This rating is assessed by the Window Energy Rating (WER) system. Windows with high energy efficiency are rated A+, with the scale going all the way to G for the lowest energy efficiency. New windows must be rated at C or higher in order to be installed.

The British Fenestration Rating Council (BFRC) assesses the energy efficiency of windows using three different values: G-value, L-value and U-value.

  • G-value: How much heat the glass gets from direct sunlight, rated from 0 (less heat) to 1 (more heat).
  • L-value: How much air leaks from a window. Ratings start from 0 (less air escapes).
  • U-value: How much heat a window keeps inside. Ratings start from 0 (keeps the most heat in). A window with triple glazing will normally have a U-value of around 0.8, compared to:
    • 1.6 for new double glazing
    • 3 for older double glazing
    • 5 for single glazing

Combined, these three values will give the window its WER from A+ to G.

Glazing at Stanmore

Stanmore provides various types of glazing, doors and windows for commercial and residential buildings. Our services vary from installation, emergency repairs, security improvement and draught-proofing. Customers enjoy high-tech glazing with durable fittings, ensuring longevity and peace of mind.

Meeting your requirements is our primary goal, no matter how simple or challenging they may be. 


Our glazing solutions adhere to stringent quality standards and are safe for multiple uses, including flooring, sound-proofing, high-rise windows, listed buildings, and entrances, in any size, shape or colour.

Our staff

Our glazers have years of experience working with different types of windows, while our fitters are highly skilled in the handling, fitting and care of the glass. They undergo continuous training to enhance their skills as technology evolves.

We offer a project team based on the skills and experience required for a specific job.

Materials used

At Stanmore, we offer windows and doors in either aluminium or composite as part of our façade solutions. We work closely alongside some of the biggest brands, including Reynaers, Schüco, Kawneer, and AluK.

All our aluminium doors are PAS 24 and SBD tested to meet the current security level for communal entrances. We only offer automatic sliding/swing door systems to BS7036/EN16005 automatic door legislative standards. We can also offer LPS1175 steel panel doors with louvres for tough bin store doors.

Our curtain wall systems are CWCT tested, with the ability to carry heavy and high-specification double/triple glazed units. The polyamide thermal isolator in the aluminium systems reduces the building’s heat loss to retain energy. 

Contact Stanmore for more information on glazing for windows and doors.