Building work obstructs smoke vent function, CROSS-UK warns

Potential safety issues with inoperable smoke vents

CROSS-UK has issued a Red Safety Alert regarding the risk posed by construction activities rendering Automatic Opening Vents (AOVs) inoperable in buildings.

The alert, aimed at fire safety managers, contractors, and building designers, addresses how AOVs, critical for releasing smoke in emergencies, can become ineffective due to building work.

According to the safety notice, these vents are a component of smoke control systems, essential for facilitating occupant escape and supporting firefighting efforts during a fire.

The alert highlights that AOVs, which can resemble ordinary windows, are sometimes inadvertently obstructed.

Incidents where façade materials block AOVs have been reported to CROSS-UK’s confidential system.

In some cases, AOVs were found masked or rendered inoperable when scaffold poles or cladding adjustments interfered with their operation.

Recent cases of obstructed AOVs during building works

CROSS Safety Report 1347 provides examples where AOVs were left inoperative for months following cladding remediation.

The first case involved improper disconnection of AOVs from their electrical components, while another case noted cladding screws fixed into AOV frames, disrupting functionality.

Report 1380 further noted instances where construction workers unknowingly covered AOVs during façade work, inhibiting their emergency use.

These reports underscore the importance of clear identification and consistent accessibility of AOVs in active construction zones.

In response, CROSS recommends the implementation of signage and better training for workers to recognise and protect these fire safety elements.

Fire risk assessments and interim measures advised

CROSS advises that fire risk assessments be updated before and during construction activities that could affect smoke vent function.

Additional interim control measures, such as temporary markings on AOVs to signal their importance, may mitigate risk.

CROSS also recommends evaluating evacuation strategies, especially for buildings with combustible cladding undergoing remediation, as AOVs play a critical role in smoke control and occupant safety.

Contractors and building managers are encouraged to understand the implications of construction activities on fire safety provisions, with special attention given to the operational status of doors, smoke detectors, and AOVs.

Obstructions such as scaffold poles, stored materials, or temporary coverings can easily disable AOVs, leading to potential hazards in a fire.

Guidance on safety compliance and training

CROSS suggests that contractors, especially those working in high-rise residential buildings, ensure all AOVs are identifiable and accessible throughout building works.

As an additional safeguard, CROSS advises signage indicating the presence and importance of AOVs.

Enhanced training is also encouraged for all construction personnel to increase awareness of AOVs’ role in fire safety.

Under the Fire Safety (England) Regulations 2022, any high-rise residential buildings with faulty fire safety equipment must report these issues.

CROSS continues to provide information and support to professionals involved in managing fire safety systems.

Building work obstructs smoke vent function, CROSS-UK warns: Summary

In November 2024, CROSS-UK issued a Red Safety Alert concerning construction work that can inadvertently render Automatic Opening Vents (AOVs) inoperable.

AOVs, which often look like regular windows, are essential in smoke control systems to assist in fire evacuation and firefighting.

CROSS-UK reports cases where AOVs were blocked by scaffold poles, cladding adjustments, or masking during building work.

To address this issue, CROSS-UK recommends updating fire risk assessments and employing signage and training to ensure AOVs remain accessible.