Qwood and Dark Colours

15 July 2026

Understanding Thermal Performance

Dark-coloured windows and doors continue to grow in popularity, with anthracite greys, blacks and other contemporary finishes now widely specified across both modern and traditional properties. While these darker finishes create a striking appearance, they also influence the way exterior building materials respond to solar heat. Understanding these effects helps ensure the long-term performance of windows and doors. In this technical guide we will provide handy tips and advice for when darker colours are used on Qwood.

Why do dark colours require extra attention?

All external building materials absorb heat from sunlight. Dark colours absorb significantly more solar energy than lighter shades, resulting in higher surface temperatures.

This is measured using Light Reflectance Value (LRV), which indicates how much visible light a colour reflects.

• High LRV colours, such as white, reflect more sunlight and remain cooler.
• Low LRV colours, including black and very dark greys, absorb more solar energy and can reach considerably higher surface temperatures.

For this reason, darker finishes require additional consideration when specified for external joinery, particularly on buildings with high levels of sun exposure.

Colours formulated using carbon black pigments are especially effective at absorbing and retaining heat, making thermal performance an important design consideration.

Qwood compared with traditional timber

Qwood has been developed to provide a highly stable alternative to traditional timber glazing and drip beads.

As a natural material, timber responds to changes in moisture, temperature and humidity, which can lead to movement over time. Qwood has been engineered to minimise these effects, providing improved dimensional stability and more consistent performance.

This enhanced stability is one of the reasons Qwood is specified by manufacturers and joiners throughout the UK and overseas.

Dark colours and Qwood performance

Although Qwood offers significantly greater dimensional stability than traditional timber, all external materials are affected by temperature.

Qwood is manufactured to perform reliably in demanding environments, with over 2 million metres of bead produced annually and only a very small number of reported performance issues.

Where issues have been investigated, they have typically occurred in particularly demanding conditions involving a combination of:

• Very low LRV finishes, including black, anthracite and other dark colours
• South-facing elevations with prolonged solar exposure
• Beads that were insufficiently fixed or restrained during installation

Reducing any of these factors significantly lowers the likelihood of thermal movement.

While Qwood remains highly stable, performance is further enhanced when beads are securely installed and properly restrained. The more effectively the bead is fixed, the better it can accommodate temperature fluctuations without movement.

Best practice for dark-coloured Qwood

For finishes with an LRV below 15, we recommend the following installation practices.

Secure beads at key fixing points

Ensure beads are firmly secured, particularly around:

• Rail junctions
• Mitre joints
• Corners and other vulnerable areas

Providing additional restraint helps minimise movement caused by thermal expansion.
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Use full-length clips wherever possible
For clip-on glazing and drip beads, use full-length clips wherever practical (We supply bead clips in 3m lengths). The greater the level of restraint, the lower the potential for movement under elevated temperatures.
Apply a white primer beneath dark topcoats
Using a white primer beneath dark paint finishes helps reduce heat absorption.The lighter base coat reflects more solar energy, reducing peak surface temperatures and helping minimise thermal stress within the finished assembly.
Avoid translucent sealers and lacquer finishes
Translucent coatings and lacquers are not recommended for use with Qwood. Always follow Qwood's finishing recommendations to achieve optimum performance and durability.

Tested coating systems

Qwood has been tested with coating systems from leading paint manufacturers, with nine independent test reports covering a range of finishing systems. These reports are available to download from the Qwood website, giving manufacturers and joiners confidence when selecting compatible coatings.

The Qwood Advantage

Dark finishes can be successfully specified on external joinery, provided the effects of solar heat gain are considered during product selection, finishing and installation. By combining enhanced dimensional stability with good installation practice, Qwood offers a reliable alternative to traditional timber beading, delivering consistent performance, ease of installation and long-term durability. For technical advice, finishing recommendations or further product information, please contact the Qwood technical team.

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