Rooftop snow and ice poses threat

Dec 7 2010 by Denis Brown, Perthshire Advertiser Tuesday

SNOW massing on Fair City rooftops could prove fatal to pedestrians if it falls with tiles or guttering attached.

Police have issued an alert about the danger of snow and ice cascading from rooftops, urging people to avoid walking directly under roofs.

“The weight of some snow resting on rooftops is considerable and we are already dealing with reports of guttering being brought down and large amounts of snow and ice sliding off roofs,” said a spokesman yesterday.

“We need local residents to be careful of where they are walking and to avoid walking directly under roofs.”

Perthshire resident and roofing expert Roger Thomas warned that roof tiles brought down could prove fatal.

“If the snow has a good, frozen purchase on underlying tiles it could bring them down on the pavement below,” he said.

He said the increase in loft and roof insulation during recent years had increased the risk as reduced heat loss through the roof could allow more snow build-up and cause “slumping”.

“The biggest danger could be on steep roofs with an angle of 50 degrees if snow and sub-zero temperatures are maintained,” he said.

“This is the critical angle for the most stable type of snow build-up.

“If snow does start falling the safest place would probably be staying near to the wall of the building until the fall has finished to avoid any tiles which could be brought down off a steep roof with the snow.”

He added that wet snow had a lower critical angle but less chance of pulling tiles down, especially if above a less insulated roof.

A Tayside Fire and Rescue spokesman underlined the potential risks posed by the extreme conditions and called for vigilance from residents.

“The public should be aware of the risk of additional loading on roofs due to the amount of snow and the risk of snow and icicles falling from roofs,” he said.

“Frozen ponds and waterways may look inviting to walk across but should be avoided due to the potential danger of falling through the ice.”

The police spokesman said anyone with concerns about accumulated rooftop snow should alert police by calling 0300 111 2222. The fire service’s advice line is 01382 322222.