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The best types of glazing for bifold doors

One of the biggest appeals of bifold doors is that they offer stunning views and create brighter rooms. 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.

In this guide

Insulation is incredibly important for any external door - this section will explain the main reasons why.

U-values offer a way to measure thermal efficiency - this section will explain the key points you need to understand.

This section details the three types of glazing: single, double and triple.

A handy comparison table that compares the main types of glazing by thickness, cost and average U-value.

External doors need to ensure thermal efficiency, but internal doors don’t - this section details why.

The importance of insulation for external bifold doors

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

Choosing energy-efficient glazing 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

The U-value measures how effective a material is at insulating. The lower the U-value, the better the material is at insulating the building.

U-value 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.

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

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

  • 1.8W/(m2K) when replacing any existing doors
  • 2.0 W/(m2K) for new build doors or extension doors

All bifold door sets should be 1.8W(m2K) but the lower that number is, the better. Vufold’s Ultra range offers U-values of just 1.0W(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 type of glazing you wish to purchase as it will have a dramatic effect.

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 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 gap between them. This gap ensures a minimal amount of energy is passed between the panes.

Gas is often used between the panes of glass. 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.

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. 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 neighbors.

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 range combines triple glazing with a combi timber/aluminium frame with a U-value of just 1.0 W/m2K.

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 commonly in countries with cold climates, or in high-end bifold doors.

Glazing Options Comparison Table

The following table is average U-value for centre pane glass. Both the double and triple U-values are based on glass that is argon filled.

Cost Thickness Average U-Value**
Single Expensive. Rarely available Thin, poor insulation 4.8 - 5.8 W/m2K
Double Reasonable. The most cost-effective Average 1.1 - 1.4 W/m2K
Triple The most expensive Thickest 0.58 - 0.8 W/m2K

*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.

Do internal bifold doors require double glazing?

The short answer is no.

Internal folding doors do not require the same level of thermal efficiency as less heat will transfer through them. Double glazing will significantly increase the price of the doors with little added value. Double glazing may also increase the thickness of the door and reduce space.

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.

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