FIRE SAFETY | TRAPEZOIDAL SMOKE STOPPERS if there are no plugs in the perforated beams buildings corridors or means of escape as roofing support, reducing roofing build costs. Each perforated beam should have a trapezoidal smoke stopper fitted, each side of the beam across the corridor. Thameside Fire Stoppings school surveys suggest a number of schools built since the year 2000 do not have smoke plugs fitted into the perforated decking because, at the time of build, their importance may not have been understood, and their role in smoke control may have been deemed unnecessary. During sign-off, building control or building risk inspectors may not have been trained on or aware of the risks in buildings where smoke stoppers are not fitted over escape corridors. Currently, no provision exists in Approved Document B for perforated lining decks to have smoke plugs installed between walls. It relies on best practice, competence and the training of installers to ensure safety is number one in their locker when installing roof perforated trays or cross-beams, and fitting smoke stoppers across escape routes or corridors in schools. If smoke stoppers were specified by the building designer, but not installed at the time of roof build, this is a latent defect, and a symptom of non-compliance and lack of competence, as with the roof fitted and closed off it would be difficult to rectify the problem. If smoke plugs have not been placed within the roof decking, and a fire starts in a classroom adjacent to the means of escape, smoke would pass upwards to the ceiling, travel around the fire room and into the perforated beams. As it cools, it could drop through the perforated decking above the dividing wall and into the escape route, potentially creating a smoke-logged area. Smoke could travel along the corridors length through each perforated cross-beam, flowing into other classrooms and leading to rapid smoke spread throughout the building. Solving the problem One fire-prevention product designed to prevent smoke from a fire spreading through perforated beams into an escape route is the Cori-Seal System, from Thameside Fire Stopping Services. It is aimed at schools with unplugged perforated decks and involves fireresistant material being sprayed or brushed onto the underside of perforated cross-beams over school corridors. The material hardens and creates a protective seal that hot smoke cannot penetrate. When tested, the material met a 30-minute fire test for smoke at 600oC. The company originally considered drilling additional holes into the perforated deck to inject fire-resistant foam. However, perforated deck supplier Tata Steel warned this would weaken the decks strength. Support beams or decks are perforated with holes to achieve the designated acoustic or noise level; this also reduces beam weight, while still maintaining the specified roof-beam strength. When they come into effect, new building safety regulations will take breaches of building safety seriously, especially where a smoke and fire issue has been raised and not addressed. So, check perforated decks, and dont leave fire and smoke safety control measures to chance. CJ ALLAN HURDLE is smoke control consultant at AKH Services and a consultant for the Cori-Seal System References: 1 Information compiled by the Zurich data science team through a freedom of information request to the UK Fire and Rescue Services. Trapezoidal trays with smoke plugs 46 July 2021 www.cibsejournal.com CIBSE July 21 pp45-46 Smoke stoppers.indd 46 25/06/2021 18:30