Qwood and Dark Colours

Qwood and Dark Colours: Understanding Thermal Performance 

Dark-coloured windows and doors have become increasingly popular, with anthracite greys, blacks and other contemporary finishes now widely specified across modern and traditional properties. 

While dark colours can create a striking aesthetic, it is important to understand how colour choice can influence the thermal performance of exterior building products. 

At Qwood, we believe in providing clear technical guidance to help manufacturers and joiners achieve the best possible long-term performance from their windows and doors. 

Why do dark colours require consideration? 

All exterior building materials are affected by solar heat gain. Dark colours absorb more radiant energy from sunlight than lighter colours, which can result in increased surface temperatures. 

This is measured using Light Reflectance Value (LRV). 

LRV indicates how much visible light a colour reflects: 

• A high LRV colour, such as white, reflects more light and absorbs less heat. 
• A low LRV colour, such as black or very dark grey, absorbs more solar energy and can result in higher surface temperatures. 

For this reason, dark-coloured finishes require additional consideration when used on external joinery, particularly in highly exposed locations. 

Any colour using “carbon black” as the most common pigment to darken the colour – is especially prone to absorbing and holding heat. 

How does Qwood perform compared with traditional timber? 

Qwood has been specifically developed to provide a more stable alternative to traditional timber beads. 

While timber is a natural material that can experience movement due to changes in moisture, temperature and environmental conditions, Qwood offers significantly improved dimensional stability. 

Compared with traditional timber beads: 

This stability is one of the key reasons why Qwood is trusted by manufacturers and joiners across the UK and internationally. 

Understanding dark colours and Qwood performance 

Qwood is significantly more stable than traditional timber, meaning the common movement issues often associated with timber beads are greatly reduced. 

We manufacture over 2 million metres of Qwood bead annually, with only a very small number of reported issues. In the reported issues we have investigated, the factors have typically involved highly exposed locations with a combination of: 

• Very low LRV paint finishes (blacks, anthracites and very dark greys, greens) 
• South-facing elevations 
• Beads that have not been sufficiently fixed or restrained 

If any of these factors can be improved upon, the risk of issues with Qwood are significantly reduced. 

Extreme, localised temperatures can affect the dimensional stability of any exterior joinery. While Qwood remains highly stable, performance in demanding conditions is improved further when the bead is correctly installed and securely restrained. 

The more securely the bead is fixed, the better it will perform when exposed to extreme environmental temperature changes. 

Best practice recommendations for dark-coloured Qwood 

For dark colours with an LRV below 15, we recommend the following installation guidance: 

1. Securely fix beads at key points

Ensure beads are adequately fixed, particularly at: 

• Rail junctions 
• Mitre joints 
• Corners and vulnerable areas 

Additional restraint helps minimise any potential movement caused by thermal expansion. 

2. Use full lengthsof clipswherever possible 

Use full lengths of clips for of clip-on drip beads and glazing beads. The more the bead is held, the less risk there is of movement.  

3. Use a white primer beneath darktop coats

A white primer coat beneath dark finishes can help reduce heat absorption. 

The lighter base layer reflects more solar energy, helping to reduce peak temperatures and minimise thermal stress within the finished joinery.  

4. Do not usetranslucent sealers and lacquers 

Translucent coatings and lacquer finishes should not be used on Qwood. 

Always follow the recommended finishing guidance to ensure optimum performance. 

Tested finishes and technical support 

Qwood has been tested with finishes from leading paint manufacturers, and we have nine available test reports covering different coating systems. 

These documents are available to download from the Qwood website, providing manufacturers and joiners with confidence when specifying and finishing Qwood products. 

The Qwood difference 

Dark colours are a design choice that requires consideration on any external building material. 

The key is understanding how colour, exposure and installation methods work together. 

Qwood provides significant advantages over traditional timber beading through its enhanced stability, consistency and ease of installation. By following simple best practice recommendations, manufacturers and joiners can confidently use dark-coloured finishes while achieving a high-quality, long-lasting installation. 

For technical guidance, product information or finishing recommendations, please contact the Qwood team.

Next in the knowledge bank

Qwood Clips: Achieving the Best Installation Performance 

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