30.08.2021, 23:11
Fire Resistant Anchors
Following a series of highly publicised losses of life to fire in refurbished buildings, Cintec International provides guidance on the importance of fire resistant remedial anchors and reinforcements.
In recent years, the risk of fire has become of increasing concern when buildings are being retrofitted, restored, or modernized.
London
On 14 June 2017, a fire broke out in the 24 storey Grenfell Tower following failures by design in an incident that was widely reported as the United Kingdom’s worst residential fire since the second World War.
As concerns over fire safety spread through the country, Prime Minister Theresa May ordered a public inquiry. As stated in the final report of the review of building regulations and fire safety, England is by no means alone in needing to improve building safety, as building regulations are a global concern.
Under the terms of the European Comission’s Construction Products Directive (which was then in effect in the UK), resistance to fire is one of the essential requirements for which performance tests are required. Across European, thin-joint mortars have become popular, thus there are a number of situations where fixings are made using organic polymers as either the tie body, or in the form of resin glues. Such ties are not inherently fire resistant and could fail and shorten the life of a cavity wall in a fire, or lead to the collapse of cladding resulting in danger to escaping occupants and fire fighters.
As a leader in structural preservation, Cintec has always been an advocate for the restoration of safe buildings through fire-resistant anchors, as long ago as 1993 fire tests were carried out by the internationally recognized Building Research Establishment in accordance with BS476 and ISO and CEN requirements. The fire rig was designed for use in the measurement of the performance of our anchors in fire situations whilst under mechanical loads that might result from wind suction as a consequence of fire-induced thermal movement.
Our remedial anchors survived a two-hour test without failure of any of the samples. Every sample reached several hundred degrees in the part of the anchor nearest to the fire face. This indicates the anchor system can be recommended for repair work to buildings requiring a fire rating of up to two hours.
More recently, anchors were unintentionally put to the test at the Fullers Brewery in London where a system that had been used extensively to repair and restore the brewery’s facade was subjected to a fierce fire that destroyed large sections of the building. Despite the brickwork being subjected to extremely high temperatures, tests revealed that the cementitious anchors did not fail and performed to their original specifications – retaining their integrity to such a degree that they could be reused for the repair work.
Had the anchors been manufactured from epoxy or another resin, they would certainly have melted, and released potentially dangerous fumes in the process and have been easily pulled out, allowing the wall to collapse.
New York City
Under NYC Buildings Department rules, adhesive anchors are not permitted to support fire-resistance rated construction unless their use meets conditions set forth in the acceptance criteria. Post-installed anchors in masonry must be designed in accordance with the NYC Construction Codes, describing the masonry substrate type and condition, as well as proof of pull tests.
Howard Zimmerman, the well-known NY Architects, had concerns about the lack of fire ratings for resin-based anchor systems in high rise apartments near Central Park. After reviewing Fire Test Data and performance tests on a severely damaged building after a fire, it was determined that one of our systems was the best anchor to meet project engineer concerns.
The anchors specified were cementitious, fire-resistant alternatives to resin anchors, and manufactured from reliable restoration materials, cementitious grout and stainless steel.
Author
