Double Glazing, French Doors, Patio Doors - Sliding Doors, Wooden Windows

What glass should you choose for windows and doors?

We offer various glazing options for you to choose from for our double-glazed windows and doors. Which option you choose will be influenced by factors such as area of use i.e. panoramic sliding doors or part glazed single door, your budget and property style. You can choose between various glazing options such as different types of glass, glass thickness and other features.
Below, we have given an overview of the different glazing options available and tried to condense all the main features. Hopefully this will make it easier to choose the best glazing option for your project. Please do contact us to discuss in more detail or if you have any specific questions.
The following options are the most common choices of glazing for our customers.

Two ordinary annealed glass panes, Un-tempered or tempered?

This option comprises of double-glazed window units with ordinary 4 or 6mm thick glass panes. Both outward and inward facing panes have the same properties. For smaller to medium size windows which are fitted 90cm or higher from floor, then standard un-tempered 4 or 6mm glass offers a very affordable price.

What is the difference between tempered and un-tempered glass?

Good question. Visually you are unlikely to see a difference between un-tempered and tempered glass, which is also sometimes referred to as hardened glass. Un-tempered glass will splinter when broken, often into jagged shards. Obviously, this has the potential to cause serious injury, if for example it was used to glaze a glass door. That is why un-tempered glazing cannot be used in applications below 90cm from the floor or for glass doors.
Tempered or hardened glass has a greater resistance to shock and so will not break easily. When it does break, it will shatter / crumble into small granular chunks and will not splinter. The granular chunks are less likely to cause injury. Being stronger and the way it shatters, makes it suitable for use in low level applications, doors or where you may get the odd football from the back garden booted into it!


If the windows are small to medium size and 90cm or more from floor height, then there is no need for tempered glass, and this will save money. Our standard windows come with 4mm and 6mm thick glass panes, depending on the size, use and customer preferences. 6mm glass panes will also provide better noise resistance.

One ordinary and one selective glass pane

This is very similar to the above two ordinary annealed glass panes option. Available in 4 – 6mm glass / tempered or un-tempered etc and is suitable for smaller and medium sized windows installed 90cm from the floor or more. The difference here is the selective glass pane we use for the inside pane.
Selective glass is also known as “smart glass”. Selective glass panes offer improved thermal insulation and adapt to external weather conditions. This glass will achieve a U-value as low as 1.1 which will significantly reduce energy costs for heating during colder months and keep your rooms cooler on hot days.


Selective glass is a little more expensive but can be effectively used to improve the performance of ordinary annealed glass panes. You will benefit from energy savings and improved room comfort.

Two layers of toughened safety glass

4mm tempered (hardened) glass is the most common choice of our customers. Tempered glass is three to four times stronger than standard glass. The annealing process for tempered glass is a much slower process, making it stronger and safer. When broken, toughened glass shatters into small granular chunks instead of splintering into jagged shards. The granular chunks are less likely to cause injury.


We offer 4mm or 6mm thick toughened glass. This is a great choice for all applications and offers safety and value.

Toughened safety glass with toughened selective glass

Like double glazed windows with two toughened glass panes, this is a strong and safe glazing option. With this option, we insert one glass pane made from toughened selective glass. This side faces in to the room and greatly improves the thermal efficiency of the window.
Selective glass is an energy efficient glass that can reflect up to 70% of indoor heat in cold weather and helps keep your home or office warm with less energy input. This clever and adaptive glass also reflects heat back out which keeps your room cooler in hot weather. These windows are available with 4mm and 6mm thick glass panes.


This option is suitable for all applications and will help always maintain a pleasant temperature without sudden variations in temperature change. Safe, secure with exceptional U-value thermal performance. The additional production cost of these windows will be offset with efficiency savings and room comfort.

Laminated selective glass and tempered (toughened) glass

Finally, we have the option of double-glazed windows and doors with the outer glass pane made from tempered glass and the inner pane made from laminated selective glass. In the text above we have explained the advantages and features of tempered and selective glass.

Laminated glass is a type of safety glass and will hold together even when shattered. In the event of one of these panes breaking, it is held in place by a thin 0,1 mm polymer interlayer that is not visible to the naked eye. 

It is exceptionally difficult to break 6mm toughened glass, in addition, the lamination on this glass will still hold the pane together without falling out. The selective glass keeps your home warm during colder months and cooler during hot summer days.


This type of glass is ideally suited for commercial applications or where there is a high chance of sudden impact.