Roofs collapsed by snow prompt design rethink in Scotland

The design of farm buildings in Scotland is likely to change markedly after heavy snow this winter caused more than 3000 barns to collapse.

The sharp crack of a stanchion bolt shearing under the pressure of weight it was never designed to bear was the first warning for countless Scottish farmers earlier this year that a steading was about to collapse.

In other cases the purlins bent so much they pulled the stanchions together and uprooted them from their concrete bases. Modern portal frame buildings were among the first to crumple. Dutch barns and traditional byres tumbled. Fibre cement, asbestos and box profile roofs all caved in as their supports fell, leaving an ugly trail in parts of Scotland’s countryside akin to the impact of an earthquake.

Agricultural loss adjuster Agrical conservatively estimates that at least 3000 farm buildings came down or were damaged and not all of them were insured. NFU Mutual received 500 claims but said that many farmers had failed to insure the building contents.

The worst-affected area is believed to be the Grampian region, and within a 35 mile radius of the market town of Huntly there’s barely a farm which hasn’t been affected. One farmer there lost three buildings and was insured for none of them. Another had five buildings brought down by the weight of increasingly heavy snow and ice after three weeks of exceptional weather.

collapsed-building-scotland-2010At the heart of the problem was the fact that these roofs had been designed to withstand snowfall of 300-600mm (1-2ft). In January there was no wind to blow away an increasingly heavy 900mm (3ft) thick snow layer which had soaked up rain like a sponge and then froze again. And it could have been much worse; farm building design experts claim that if just 50mm (2in) more rain had fallen countless more structures would have toppled.

The scale of the problem prompted the Scottish government to convene an emergency working group which comprised technical experts, insurers and industry bodies and led to a £3m fund for aid to producers to construct temporary sheds to cater for the forthcoming lambing season or pay for accommodation for livestock on other premises.

To meet state aid rules, the money was assigned purely for animal welfare purposes with a maximum pay-out per farmer of £6000.

A similarly rapid response came from insurance companies and loss adjusters who say they have now visited all the affected premises. Ron Caley, technical and large loss director of Agrical, was on the working group and said the removal of debris and estimates for new buildings were now well under way.

He added: “We are very conscious of the problems being faced by farmers and the urgency of the timescale. They need lambing sheds imminently and need to have new stores in place for grain at harvest time so we are doing everything we can to avoid a knock-on effect to the efficient running of businesses.

“But many farmers are not just replacing their destroyed or damaged buildings. They are talking about putting up more substantial structures and are working closely with insurers and designers to achieve the best result. That takes time.”

There is also an issue about the sheer volume of work facing farm buildings designers who are now advising on different specifications for roof pitch and steel strength. Mike Strachan, the team leader of SAC‘s buildings design consultancy is now advising farmers in parts of Grampian to reduce bay spacings from 6.1m to 4.8m or even 4.1m and to increase roof pitch from 15° to 22.5°. But this year’s experiences may lead to an even more fundamental review.

Mr Strachan added: “Over the past two decades buildings have been getting bigger and spans wider but in future we may start looking at replacing these massive structures with two or even three individual structures. It might make sense to bring the scale back down, and that has other benefits such as reducing disease.”

collapsed-building-scotland-2010-2Construction companies have also been inundated with requests for quotes and in many parts of the country order books are now full. Grampian Construction of Huntly, for instance, is at the epicenter of the problem area and has been inundated with inquiries from farmers. Director Kenny Riddoch explained that they usually construct 10-15 new farm buildings a year, but already in 2010 they have priced substantial repairs and alterations and quoted for 45 new buildings. Invariably farmers are asking for stronger structures.

“There’s no doubt that farm buildings are going to get heavier and more expensive,” Mr Riddoch explained. “The size of steel, the gauge of purlins and steeper roof pitches will all add to the cost but farmers never want to face a problem of this magnitude again. They are also desperate for the work to be turned round fast.”

NFU Scotland‘s north-east regional chairman Tom Johnston, who farms near Huntly and lost a grain and seed store on his own farm, said that he had been in the process of erecting another building when the snow hit.

“We have now altered the design and are placing the purlins 3ft apart instead of the 4.6ft we had planned,” he said. “There’s a financial cost but it we have to spend more to safeguard us in the future. I’ll also be using a box profile roof instead of fibre cement because it has a slippier surface and should help the snow slide off. “

NFU Mutual has estimated that this severe weather incident will cost them £20m which they say is within the normal scale of operating costs. Spokesman Kim Price said this meant premiums would not rise but he added that group secretaries would advise farmers on buildings content insurance when they reviewed their annual policies. “In some cases they have not been covered,” he said.

There’s no doubt that this winter’s exceptional weather has meant the agricultural industry had to learn some painful lessons. And the problems aren’t over yet. Mike Strachan of SAC has a chilling warning to farmers who now have tonnes of broken asbestos cement products lying around on their properties.

“That’s now my biggest concern,” he said. “While the weather remains damp the risk is minimal but as soon as the sun beats down and there’s some wind the fibres will spread widely. The implications of that are very serious for farmers and their families, farm workers and the general public. It’s an issue that needs to be dealt with immediately.”