Your Guide to Timber Window and Door Glazing

When looking to replace your windows and doors, it is important to consider the type of glazing alongside the window’s U-value

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When looking to replace your windows and doors, it is important to consider the type of glazing alongside the window’s U-value.

A U-value measures how well heat is transferred from your window in or out of the building.  The lower the U-value the better the heat conservation.

Single Glazing

Often a requirement in listed buildings, single glazing is where the window or door is glazed with a single layer of glass.

All original windows and doors in period properties would have had single glazing.  However, most people now view having single glazed windows as a disadvantage due to the high level of heat loss.

Double glazed timber sash windows manufactured and installed by The Sash Window Workshop.

Double Glazing

Double glazing has been widely used for timber windows and doors for over 40 years.  A double glazed unit comprises of two sheets of glass separated by an air gap.  The air gap helps reduce the heat conduction between the panes.  This allows heat to be retained in the winter and to keep your home cooler during the hotter summer months.

To further improve thermal efficiency, gases, such as Argon, xenon or krypton, is often pumped into the airspace between the two glass panes.

While an average single glazed window will have a U-value of 4.8 this drops drastically with the installation of double glazing, with a typical double glazed window having a U-value of around 2.3.

Find out more about double glazing glass options

Triple Glazing

Triple glazing operates in the same way as double glazing but with an extra pane of glass.  It is worth noting that triple glazed windows often do not fit in period properties due to the thickness of the windows.

Casement window secondary glazing manufactured and installed by The Sash Window Workshop.

Secondary Glazing

Not to be confused with double glazing, secondary glazing is where a separate window is installed internally to improve thermal efficiency and reduce noise.  This is popular in listed buildings where double glazing or triple glazing is unlikely to be approved.

Secondary glazing provides all the thermal and noise reducing benefit of double glazing while retaining the existing windows.  However, it is worth noting that you will have to open two windows anytime you wish to circulate fresh air into the room.

Bi-fold door with safety glass manufactured and installed by The Sash Window Workshop.

Glazing Choices

Depending on the location of the window or door, there are different types of glass you can choose.  Each of these have their own specific benefits.  Below are some examples of the different specialist glass options:

Acoustic glass is designed to reduce noise coming into the property through the glass.

Safety glass is designed to shatter into small pieces when it is hit hard, reducing the chance of injury.  This is a legal requirement in glass below a certain height from the floor level.

Obscure Glass, also known as Opaque, is any textured glass and is often used for increased privacy or decorative effects.  Examples of obscure glass include frosted or etched glass.

Sash windows with obscure glass manufactured and installed by The Sash Window Workshop.

Obtaining Quotes

When replacing your windows or doors, speak to the companies you are obtaining quotes from about the different glass options.  A specialist window and door company should be able to advise you of the best glass to meet your needs.

The Sash Window Workshop have over 20 years’ experience manufacturing and installing timber windows and doors across London and South England.  The company also offer a supply only service for new joinery nationwide.  To obtain a free, no obligation quotation contact The Sash Window Workshop on: 01344 868 668