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The best types of glazing for bifold doors

Martin Burgess - Customer Service Manager

Author: Martin Burgess - Customer Service Manager

One of the biggest appeals of using bifold doors as your patio doors is that they offer stunning views and maximise the amount of natural light within your home. To offer this, bifold doors are mostly made from glass. It is important to consider the type of glazing you wish to have with your bifold to ensure optimum thermal performance.

In this guide, you will find information on the importance of insulation, U-values and the main types of glazing.

The importance of insulation for external bifold doors

Part open bifolds Part open bifolds

Glazing can make all the difference to the insulation and energy efficiency of your home, saving you money on your energy bills. When you’re looking to install bifold doors as your patio doors, or French doors or sliding doors, you should be sure to take note of the U-value of any bifold doors you are considering (see below).

Choosing energy-efficient glazing for glass patio doors, as well as any window in your home, can reduce your gas and electricity bill significantly by reducing the heat loss in your home. This simple process ensures that less energy is needed to keep your home at a reasonable temperature. Less energy means cheaper bills and a reduced carbon footprint.

Bifold doors are some of the most eco-friendly external door solutions on the market, when utilising double or triple glazing.

Understanding U-Values

When choosing new glazed patio doors for your home, it’s important to understand what U-Values are and what they mean.

The U-value of glazing measures how effective a material is at insulating. The lower the U-value, the better the material is at insulating the building. This U-Value applies to any glazed door or window you’re looking to install within your home.

The U-value of the glazing you choose should be a significant consideration when choosing external bifold doors as the U-value of a door will have a major impact on how much heat is lost from your home. The more heat lost, the more expensive your energy bills.

It is important to be mindful that when advertising U-values, businesses sometimes publish the U-value of the centre pane of glass only. This is because the glass is often a better thermal insulator than the frame material.

Building regulations apply to the U-value of the whole door set not just the glass, to avoid any issues ensure you have the U-value of the complete door set. The U-value of a bifold door applies to both the frame and the glazing you choose so it’s important to calculate the U-value of the material and glazing carefully.

What is a good U-Value for an external bifold door set?

Closed white bifolds Closed white bifolds

There are regulations around U-values which outline that any door set must be at least:

  • 1.4 W/m2K when replacing any existing doors
  • 1.6 W/m2K for new build doors or extension doors

All bifold door sets should be 1.4 W/m2K but the lower that number is, the better. Vufold’s Ultra range offers U-values of just 1.0 W/m2K!

Types of glazing

The type of glazing you choose will affect the U-value of a bifold door, and therefore, it's thermal efficiency. You should carefully consider the glass options available to you as the glazing you choose will have a dramatic impact.

The three main types of glazing are:

Single glazing

Single glazing is very uncommon for external bifold doors. It is highly unlikely you will be able to purchase external bifold doors with single glazing.

Key information:

  • Single glazing is a single pane of glass, which means that it is the least secure of all glazing types
  • Single glazing provides the least amount of thermal insulation
  • Single glazing is typically used in listed buildings or with internal bifold doors

Double glazing

Double glazing is the most common and cost-effective option for bifold door glazing. It is created by placing two panes of glass with a hermetically sealed unit between them. This gap ensures a minimal amount of energy is passed between the panes.

Gas is often used between the double glazed unit. Vufold uses Low-E (low mission) Argon gas to ensure optimum thermal efficiency. Other gases are available such as Krypton, however, these are much more expensive with little benefit. Double glazing is highly effective at protecting your home from the elements and, coming in at a much lower cost than triple glazing, is a popular option for homeowners in the UK.

Benefit 1: Excellent thermal efficiency

The space between the two panes of glass provides added insulation, improving the U-value and thermal efficiency of your home. Double glazing can help to keep your home both warm in the winter, and cool in the summer. As the UK climate rarely experiences extreme weather conditions, double glazing is usually sufficient enough to protect your home unless you live in a more exposed area. The improved thermal efficiency of double glazing means that you can enjoy a reduced heating bill in the winter and a cooler room in the summer.

Double glazing can help with noise reduction. Sealed double glazing is excellent at minimizing noise from human voices, cars and other outside sounds, which is perfect if you live on a busy street or have noisy neighbours.

Benefit 2: Increased security

Double glazing is safer than single glazing. The two pane technology means the windows are thicker and harder to break. The double panels burglars need to break through will take longer, create more noise and require more effort.


If the seal used to join the two panes of glass breaks down, you will notice condensation. However, this is unlikely to be an issue if you purchase from a quality retailer.

Triple glazing

Triple glazing operates in the same way as double glazing, using a pocket of air between panes of glass to improve insulation. However, as the name suggests, in triple glazing, there are three panes of glass rather than two. Triple glazing offers exceptionally high performance when it comes to thermal efficiency and can significantly reduce external noise.

Triple glazing costs more than single or double glazing, but you will likely save money on your energy bill, especially when combined with insulated materials. For example, Vufold’s Ultra composite bifold doors range combines triple glazing with a combi timber/aluminium frame with a U-value of just 1.0 W/m2K.

Due to its nature, triple glazing can be extremely heavy which can put a strain on the hinges and frames of your folding doors so finding the right frame material is important. Aluminium frames provide the strongest support for triple glazing when compared to other materials. Learn more about the comparisons between different bifold door materials in our guide.

The Ultra range of bifold doors combines resilient aluminium cladding on the outside and oak on the inside which allows you to match your doors to both the style of your home and your interior décor.

With triple glazing, the depth of the door may increase too, so this can be an additional consideration where space is a factor. Triple glazing is most common in countries with cold conditions, which rarely occur in the UK, or in high-end bifold doors.

In addition, triple glazing can not only cost more initially, but the cost of delivery and installation can also be higher too due to the weight of the doors. This is something to bear in mind when choosing triple glazing for your home.

Glazing options comparison table

The following table provides more information on the glazing options available for bifold doors. Both the double and triple U-values are based on glass that is argon filled.

  Costs Thickness Average U-Value ** Pros Cons
Single Expensive. Rarely available. Thin, poor insulation 4.8-5.8 W/m2K Poor
  • Suitable for warmer climates
  • Can be installed into older windows and door frames
  • Lack of insulation
  • Lack of noise protection
  • Not secure
Double Reasonable. The most cost-effective. Average 1.1-1.4 W/m2K Good
  • Well insulated
  • Energy efficient
  • Can reduce outdoor noise
  • Offers more security
  • Can trap heat
  • Can clash with older style properties
Triple The most expensive. Thickest 0.58-0.8 W/m2K Excellent
  • More energy efficient
  • Keep cold out in and heat in during winter
  • Keep home cool in summer
  • Keep noise out
  • More expensive than other types of glazing
  • Not always necessary in UK climate

*based on findings by Vufold and

**this is the U-value for the glazing only and does not include the U-value of the frame material. When looking to purchase a bifold door always look for the overall U-value.

Find out more about our full range of external bifold doors and their glazing options by clicking here.

Do internal bifold doors require double glazing?

4 door edge 4 door edge

The short answer is no, you do not require double glazing for interior bifold doors or any interior door within your home.

Internal folding doors do not require the same level of thermal efficiency as less heat will transfer through them. As interior doors are not a direct opening between the inside and outside of your home, their thermal efficiency is less important. Double glazing will significantly increase the cost of the doors with little added value. Double glazing may also increase the thickness of an interior bifold door and reduce space within your home.

Take a look at our range of internal bifold doors by clicking here.

Contact Vufold to find the perfect solutions for your bifold doors

If you wish to discuss internal or external bifold doors or glazing for bifold doors, get in touch with our specialists. We will guide you through all of your options and find the perfect solution to meet your needs and tastes.

You can contact our team today by calling 01625 442899 or email us, and we will get in touch with you without delay.

What material bifold door should you choose?

What is your priority when looking for a new bifold door?

What is your priority when looking for a new bifold door?

Do you prefer a rustic-style door, or a modern and sleek design?

What kind of bifold door style do you prefer?

Would you rather choose the natural look of oak, or finishes such as white and grey?

Which colours do you prefer in a bifold door?

Do you prefer the look of aluminium, or a combination of oak and aluminium?

Which of the following factors is the most important to you?

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Martin Burgess - Customer Service Manager


Martin Burgess - Customer Service Manager

About Martin Burgess

For customers, Martin is one of the key people at Vufold and looks to offer technical advice, resolve any issues or problems that they may have. Martin is passionate about protecting the reputation of Vufold and likes to see a positive impact on the business due to his day-to-day efforts. Martin’s proud of the team he’s built around him and is dedicated to constantly improving the way the company meets its service commitments and delivers on its promises.

Read more about Martin Burgess