Wall Tie Failure – More Schools Affected...

In January, news of Storm Gertrude hit the headlines all over the country as it carved a vicious swathe of destruction across the country. As is often the case, Scotland was one of the worst-hit areas and you may remember the story of Oxgangs Primary School in Edinburgh, where a wall collapsed due to wall-tie failure combined with Gertrude’s intensity. The story took a further twist recently as news that a further THREE schools in Edinburgh are to be temporarily closed amid safety fears.

The schools affected by this news are:

• St Peter’s RC Primary School
• Braidburn Special School
• Firrhill High School

Along with Oxgangs Primary School, these three establishments were closed while ‘further, detailed tests’ are carried out by structural experts to diagnose and potentially repair the issues. All of the schools that have been closed were built by the same contractor working under the Public Private Partnership 1 project and, at just ten years old, the structures should certainly not be showing such damage. A preliminary investigation revealed that there were several problems with the way external walls had been erected – at Oxgangs, the width of the wall cavities was incorrectly measured and the wall ties not correctly installed to the required embedment depth, resulting in their failure and the collapse of the wall.

Education Convener Cllr Paul Godzik, said that health and safety of pupils and staff is the school’s ‘top priority’, as he explained the council’s decision to close the schools temporarily. He said that the closure was: “ a purely precautionary measure… whilst the survey results have indicated that these schools could continue to operate in normal weather conditions until the necessary works are carried out, we are unwilling to take any risk. We would like to apologise to parents however I am sure everyone will understand why we have taken these steps."

Melanie Main is the Education Spokeswoman for Edinburgh Greens and agreed that safety had to be the number-one priority. “On the face of it, it looks like something has gone badly wrong with the way these private school building contracts have been handled… once any emergency work is completed it is crucial that responsibility for these failings is established."

The Buiding Research Establishment publication, BRE Digest 401, details the 'drop-off' in axial performance of traditional ties that are built into walls with wide cavities and the significant reduction in load capacity when ties are installed to an incorrect depth.  Twistfix supply the retrofit CD Wall Tie, which carries CE Marking for use in cavities of up to at least 150mm.  The one-piece stainless steel tie can be used in all types of masonry structuires and is ideal for use in remedial repairs to public buildings where fire-ratings are required.

Getting the numbers right when installing wall ties is clearly essential and that’s why we provide the Wall-Tie Calculator – a handy, accurate tool!