Storm-proofing your property - reducing your risks
While severe storms may be a fact of life in many parts of Australia, there are some simple measures your clients can take to minimise their property damage and reduce their risks of business interruption.
The word ‘storm’ is used to describe a variety of severe weather events that involve atmospheric disturbance. These run the gamut from tropical, summer and winter storms to more severe weather events with high wind and heavy rain conditions, associated with tornado, hurricane and cyclone activity.
Cyclonic storms are characteristic of the northern regions of Australia, where the low lying coastal areas are often subject to storm surge from the sea. Whereas in the southern regions, storms are often associated with thunder and lightning activity, heavy rains, localised flash flooding, land gales and destructive gusts or squalls. Coastal areas may also be susceptible to hailstorms, such as the one that hit Sydney’s east in 1999 and caused an estimated $2.3 billion in damages.
What types of storm are your clients most at risk of?
That really depends on the property’s location and the types of storm that are prevalent in that geographical region. This will in turn determine what damage mitigation measures your clients should take. Local councils and the Bureau of Meteorology are usually good sources of information about local weather conditions.
Probably the most important thing your clients can do to protect their property against storm damage in the first instance is to make sure that their building(s) and roof structure(s) are intact and don’t leak. Pay particular attention to windows and doors as once these have been broken, internal pressurisation of the building can catastrophically lift the roof off in strong winds. If your client hasn’t already done so, they should prepare an emergency plan that can be activated at short notice in the event of a severe storm warning.
Some of the basic things they need to address in their plan include:
- knowing how to tune into severe weather warning services and radio broadcasts
- preparing (and rehearsing) evacuation procedures
- pre-packing an emergency kit that includes important contact numbers (e.g. key staff, broker, insurance company etc.), a portable radio, torch, spare batteries, first aid kit and plastic bags (for clothing/valuables)
- having emergency equipment on standby (e.g. tarpaulins, rope, nails, hammer, timber, sandbags) to protect plant, stock and other building contents in the event that the storm damages the roof or wall structure
- isolating water, gas and electrical power supplies when severe storms are forecast to prevent further damage and personal injury from ruptured pipes or fallen power lines.
Protecting against wind damage
If your client’s property is located in an area that’s prone to strong winds and severe storms, it’s worth getting a builder to assess:
- how well the roof, windows and doors are secured to the building wall structure
- the building’s ability to withstand wind forces characteristic of the location
- compliance with the wind load requirements in the Building Code of Australia guidelines (as well as AS 4055-2006 and AS/NZS 1170.2-2002).
The roof’s attachment to the wall structure is critical. It is also important to make sure that any gable roof frames have adequate bracing at the gable ends. In turn, ongoing maintenance is also vital (i.e. regularly inspecting the sheet metal or tile roof cladding to ensure that it’s secured properly). The cyclic nature of the wind load can lead to the progressive deterioration of fastener strength over time. If fasteners loosen and pull out, windborne roof and wall cladding debris can cause further damage to surrounding buildings.
After severe wind events, you should always check the roof and walls for damage. Other simple but effective measures that can help reduce a property’s risk of wind damage include:
- fitting glass windows and doors with storm shutters
- installing security mesh or robust, well-fitted insect screens on windows
- protecting skylights with mesh screens
- reinforcing roller doors to withstand strong winds.
After checking the structure is secure, it’s important to inspect the building’s surroundings. Remove any overhanging branches or adjacent trees (with council permission) that could fall on the building in high winds or following a lightning strike. If space permits, plant windbreaks of trees on the prevailing windward side but well away from buildings.
When a storm threatens, be sure to secure any loose property in your yard, including lightweight sheds, metal sheets, roofing material, signs, outdoor furniture, bins and other items that could blow away and cause further damage.
Protecting against water leaks
In the event of a storm, small water leaks can rapidly turn into gushing torrents, which is all the more reason to routinely check the condition of your roof and perform any necessary building maintenance.
Some of the key things to be on the lookout for include:
- broken masonry tiles/slates, loose iron sheet cladding or lifted flashing (especially on low sloped roofs)
- corroded galvanised iron sheet roofing where buildings are located in industrial or salt-laden, coastal localities (or below dripping airconditioning units)
- membrane damage on concrete roofs, especially around edges that are susceptible to being lifted by strong winds or where plant and equipment have been installed
- moved aggregate stone coverings following a storm, exposing the membrane
- blocked or rusted roof guttering and drainage systems.
It’s important to make sure that roof guttering and drainage systems, including downpipes and rain heads, are adequately sized for sudden downpours and hailstorms. A licensed roof drainage contractor or hydrologist can provide expert advice in this area. They may also recommend that you install overflow points through external walls for box guttering and adequate flashing for saw-tooth roof guttering.
To prevent gutters from filling up with leaf litter and small branches, regularly trim overhanging tree branches and consider installing a gutter guard. If you currently have old asbestos roof cladding or old translucent sheeting, consider replacing it with sheet metal or newer translucent cladding – to avoid hailstones punching holes in the roof. When replacing roof cladding (especially tiles), it’s a good idea to install a secondary water-protection layer in the form of sarking.
Be sure to also check around windows and door frames for any gaps, where water seepage commonly occurs, and seal these also. Finally, blocked or inadequate stormwater drainage pits can cause water to back up from the ground level up to the roof during a downpour. Ensure that your stormwater capacity is adequate for your property’s needs. At the same time, identify whether any interior pits or basements require sump pumps. And if your property is in a high flood risk area, installing barriers, embankments and other measures can considerably help mitigate your risks of water damage.
Protecting against lightning strikes
Is your property located in an exposed location? Or is it the highest building in the immediate area? Then it’s worth installing a lightning protection system, which should be checked on a regular basis, including its earthing system.
You also need to assess the level of surge protection that the telecommunications and electrical systems in your building have and determine whether they are adequate for any critical or sensitive equipment. While an uninterrupted power supply, also known as a battery back-up, has some surge protection, power filtering and voltage regulation built in, this generally does not provide adequate protection against transient lightning currents. Likewise, circuit breakers and fuses are generally too slow in response time to protect against all transient spikes from lightning.
If your building is at high risk of a lightning strike, consider installing an emergency back-up power supply source (e.g. diesel generator) for critical operations. Good sources of further information include: AS/NZS 1170.2: 2002 “Structural design actions – Wind actions”; AS/NZS 3500.3:2003 “Plumbing and drainage – Stormwater drainage”; AS/NZS 1768:2007, “Lightning protection”; and the Building Code of Australia.
Want more information?Find out more about how to reduce your clients’ storm risks at Zurich’s Risk Features website.
Senior Risk Engineer Mervyn Rea, who coordinates the website, says Risk Features provides brokers and their clients with an insight into both how Zurich appraises various risks and how companies can minimise their exposures. “The Natural Hazards information on the website is a recent addition and covers storm, earthquake and flood,” says Rea.
“The content includes input from Zurich’s global network of risk engineers based in Switzerland, Japan, the US and other countries. It was developed in response to a request from one of our Global Corporate clients and is yet another example of Zurich in action.”
© Zurich Financial Services Australia March 2009.