A Guide to Glass Options for Your Bespoke Timber Windows and Doors
When investing in bespoke timber windows and doors, most of the attention naturally falls on the joinery itself. The timber species, the profile, the finish colour, the ironmongery. The glass, however, is just as important a decision. It is the largest surface area in any window or door, and what you specify will directly affect the thermal performance, security, acoustic comfort, light quality, and visual character of your home. At GK Joinery, we want our customers to fully understand the options available to them before they commit to a specification.
Standard Double Glazing: A-Rated Performance as Standard
All GK Joinery windows and doors come with energy-efficient, A-rated 24mm double glazing as standard. Using the latest glazing technologies, this achieves a U-value of just 1.2, which represents excellent thermal performance. A lower U-value means less heat loss through the glass, which translates directly into a warmer home and reduced heating bills over time. For the vast majority of residential projects, our standard double glazing unit will be the right choice. You can read more about thermal performance on our glass information page.
Specialist Glass: Expanding the Possibilities
Beyond the standard specification, we offer a range of specialist glass types to suit particular requirements.
Frosted and satin glass provides privacy without sacrificing natural light and is a popular choice for bathrooms, ground-floor side lights, and any glazing that faces a public area or close neighbour.
Acoustic glass uses a laminated construction to reduce the transmission of external noise into the home. It is particularly well suited to properties on busy roads or in areas with higher ambient noise levels, and it can make a meaningful difference to the comfort of rooms facing the street.
Self-cleaning glass uses a photocatalytic coating on the outer surface that breaks down organic dirt in sunlight and allows rainwater to sheet off cleanly. For windows in hard-to-reach locations, such as high-level glazing or roof lights, this can significantly reduce the cleaning burden.
Anti-sun glass incorporates a solar control coating that reduces the amount of heat and glare entering through south or west-facing glazing, helping to prevent rooms from overheating in warm weather whilst still admitting plenty of natural light.
Leaded and decorative glass can be specified where a traditional or heritage aesthetic is a priority, and works beautifully in conjunction with our bespoke and heritage joinery. Take a look at the doors gallery to see examples of decorative glazing in finished installations.
Single Glazing and Slim Heritage Double Glazing for Listed Buildings
For properties with listed building status or those within conservation areas, achieving the right visual appearance is often as important as thermal performance, and planning authorities may not permit the installation of standard double glazed units. In these situations, two alternatives are available.
Single glazing remains an option where conservation requirements make anything thicker unsuitable. Whilst it offers the least thermal performance, it allows the original character of the building to be preserved precisely.
Slim heritage double glazing is a more favourable solution where it is permitted. With a total unit thickness of just 12mm and a 4mm air gap filled with Krypton gas, it significantly outperforms single glazing with a U-value of 1.9, compared to approximately 5.9 for single glazing, while maintaining a very slender sight line that respects the historic character of the building. This option allows homeowners to improve comfort and thermal efficiency without a visible change to the appearance of their windows. Our downloads page contains further technical information to support your specification.
If you are unsure which glass specification is right for your project, contact us or visit our showroom to discuss your requirements with the team.
Questions and Answers
What does U-value mean and why does it matter?
A U-value measures the rate at which heat passes through a material. The lower the U-value, the better the insulation. Our standard A-rated double glazing achieves a U-value of 1.2, which is significantly better than older double glazing units and far superior to single glazing. Specifying the right glazing unit is an important part of meeting the energy efficiency requirements of Part L of the Building Regulations.
Can I have different glass specifications in different windows on the same property?
Yes. Because all of our joinery is made to order, it is perfectly possible to specify different glass types in different locations. For example, you might choose frosted glass for a bathroom window, acoustic glass for a front bedroom facing the road, and standard A-rated units throughout the rest of the property. We will advise on the most appropriate specification for each opening during your consultation.
Is specialist glass available for bi-fold and French doors?
Yes. The glass options described above are available across our full range, including bi-fold and French doors and conservatories. We will always ensure that the glass specification is appropriate for the size and orientation of the panels being manufactured.