Due to fragile geological conditions and great elevation difference, Bhutan is prone to many natural disasters. Hazards like earthquake, windstorm, fire, landslide, flash flood, glacial lake outburst flood besides, windstorm is the most common natural disaster that visit us from time to time. Damage suffered has been enormous. Every year our farmers lose acres of crops due to windstorm the frequency of which has been growing over the years triggered by change in climate. Damage on agriculture besides, it destroys homes, infrastructure and cultural and heritage sites by thousands.
For the people whose only wealth or possession is a roof over their heads, damage on the homes is costly and painful. For some, rebuilding their homes is almost unimaginable.
Human settlement ministry’s study has found that our traditional roofing system is often too weak to withstand windstorm. And the problem is aggravated by lack of maintenance and poor workmanship. “Poor workmanship in various truss joinery and connections and improvisation at site without any design basis tend to fail during windstorms,” the guideline states. “Lack of periodic maintenance is also a main cause of roof failure during windstorms. Material strength deteriorates mainly due to exposure to moisture and insect attack in absence of routine maintenance.”
In Bhutan, there are traditionally four types of roofing system – jabzhi, jamthok, drangim, and chenkhep. However, the problem is with their vulnerability that result from traditional construction practices. It has been found that when windstorms strike, they affect mostly rural homes; it is the roof of the houses that are typically damaged.
The aim of the study was to develop a windstorm resilient guideline for roofing system in the country. This initiative, which has been long time coming, is welcome.
The guideline is expected to include a number of recommendations related to construction of homes, in particular for better roofing system so that disasters like windstorm cause minimal damage to Bhutanese homes. The guideline recommends better site selection, layout and orientation of buildings, among others. Doing so will save both expenditure and agony for households, particularly in the rural pockets of the country.
Recommendations have also been made for better load path for safe delivery of wind loads from roof to foundation through proper connections. Ways to secure the CGI sheet and use of tie downs to hold the truss systems are critically important.
Now that we are inching towards having a guideline for better construction and roofing system we must look, more importantly, to effective implementation of the guideline. Otherwise, in the age of changing climate and weather conditions, trouble and expenses from disasters will continue to grow making it expensive for both households and the government.