Regulator finds widespread compliance failures in heat-soaked toughened glass sector

A UK regulator has uncovered widespread compliance issues among manufacturers of heat-soaked thermally toughened glass (HSTTG), prompting enforcement action and renewed warnings for the construction sector about quality assurance and documentation.

The findings come in a sector regulatory report published on 5 March 2026 by the Office for Product Safety and Standards (OPSS), following an inspection programme targeting UK manufacturers of the safety-critical construction product.

The OPSS carried out a series of unannounced inspections of manufacturers during 2024–2025 after intelligence suggested systemic compliance problems within the sector. The material is widely used in high-risk building applications such as high-rise developments, commercial buildings and infrastructure projects where large glass panels are exposed to public areas.

Heat-soaked thermally toughened glass is designed to reduce the risk of spontaneous breakage caused by microscopic nickel sulphide inclusions that can expand over time and cause panes to shatter without warning.

Because of this risk, the product is often specified in facades, balustrades, roof glazing and other installations where falling glass could endanger occupants or the public.

According to the report, the regulator identified “high rates of non-compliance” during its inspection programme, including failures in documentation, production controls and regulatory requirements.

In some cases, manufacturers were unable to provide required documentation such as Declarations of Performance (DoP) demonstrating that products meet regulatory standards. Data in the report shows that none of the inspected manufacturers provided a fully compliant DoP during initial inspections, although some provided partial documentation.

These shortcomings raised concerns because of the potential safety consequences if the product fails in service.

The regulator says its intervention stopped the supply of non-compliant glass in the UK and led to several businesses being prevented from selling products until issues were resolved.

The programme forms part of the UK’s wider regulatory regime for construction products under the Construction Products Regulations, which require manufacturers to demonstrate performance through testing, certification and factory production control systems.

The OPSS said the inspections were also intended to level the playing field for compliant manufacturers by tackling poor practices that could undermine trust in the sector.

The regulator reported "marked improvements" in production and assurance practices following its inspections and subsequent follow-up activity with manufacturers.

For building engineers and specifiers, the report reinforces the importance of verifying product documentation and quality assurance processes when selecting glazing systems, particularly where failure could pose a safety risk.

Industry guidance has long emphasised that designers rely heavily on manufacturer records and certification to confirm that glass has been properly heat-soaked, as the process cannot be verified visually once the glass is installed.

The findings highlight several practical issues for those responsible for building design, procurement and maintenance:

• verifying Declarations of Performance and certification from suppliers;
• ensuring compliance with standards such as BS EN 14179 for heat-soaked glass;
• considering risk mitigation where glazing is installed above areas with public access; and
• maintaining traceability and documentation throughout the supply chain.

The OPSS said it expects the sector to learn lessons from the inspections and improve practices across construction product manufacturing.

The report is available here.