When British Airways asked construction consultant Turner & Townsend to examine the condition of an ageing Sarnafil roof at Heathrow Airport, BA expected it to recommend its extensive refurbishment or even replacement. However, such extensive work was not required thanks to the longevity of the Sarnafil system.

Owner BA wanted to ascertain whether the condition of Technical Building C’s 19-year-old roof could lead to future problems as well as ensure the safety of anyone working atop the 30-metre high building – the tallest on the Heathrow site – by installing a fall arrest system.

However, thorough testing of the original Sarnafil membrane by the British Board of Agrément (BBA), revealed that the roof required only remedial works to ensure continued water integrity and bring the building, which is home to BA’s aircraft maintenance staff, in line with current health and safety regulations. Turner & Townsend commissioned Robseal Roofing, who installed the original roof, to carry out the work.

In addition, on site testing confirmed that the fall arrest system – the Sarnafil Constant Force post, developed in conjunction with Latchways Plc – could be fitted without wholesale replacement of the roof and unimpeded by compatibility or safety issues.

Roof Management area manager, Neil Smith, who oversaw the project for Sarnafil, says of the existing roof’s performance: “A building of this height is subject to significant wind loadings. Heathrow Airport is a very exposed, harsh environment and there aren’t many buildings around Technical Building C to protect it from the wind. So the roof performed well over the previous 19 years in the most exacting conditions.”

Neil believes that the need for only minimal work to the 1,500sq m roof also offered BA substantial financial and practical benefits. “To replace a roof of this size in its entirety would cost well over £1million,” he says. “Instead, the continued durability of the Sarnafil membrane and its ability to cater for building and regulatory changes meant that this remedial work cost only a fraction of that, offering vast savings for the client.”

And with health, safety and security paramount to today’s building owners, avoiding the practical challenges of installing a new roof, such as transporting materials up and down such a tall building, in an aviation setting also proved advantageous.

“BA require exacting method statements of work to be carried out, which have to be agreed by all before a project can commence,” Neil continues. “This is because it is not only the building occupants that have to be considered, but also the operation of the entire airport, with aircraft landing and taking off only a few hundred metres away. So the building’s sheer location meant minimised works were preferable.”

But having benefited the client, the Heathrow roof then went on to benefit its creator – by helping Sarnafil extend its BBA certified life expectancy from in excess of 30 to in excess of 40 years.

“A 2sq m sample of the original roof was passed on to the BBA along with several other Sarnafil samples to be thoroughly tested against an un-aged material,” says Neil. “The results have since enabled the BBA to increase the Sarnafil system’s life expectancy for the membrane to a life in excess of 40 years with periodic maintenance.”

Neil concludes: “People always assume a 20-year-old roof has had its day, but now – with appropriate maintenance and even under extreme conditions of usage – Sarnafil can say with confidence that this is not the case.”

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