New research indicates garage doors in high-wind areas are just as susceptible to being blown out from within as being blown in from outside.
Technical expert Terry Hardie of Australian garage door specialist B&D Doors & Openers said home owners in cyclone-affected regions are aware of the potential for garage door failure due to high exterior wind force, yet a garage door’s susceptibility for blow-out remains relatively unknown.
“Blow-out pressure can actually be greater than blow-in pressure – and therefore resistance to it is just as crucial,” said Mr Hardie.
“Depending on wind pressure direction and a garage door’s location on a building it can get blown out from within, exposing the garage’s contents – and potentially the greater building – to damage.
“If a garage is exposed due to door failure then internal pressures can concentrate within the garage and potentially breach the rest of the house.
“At worst, the roof can pop right off.”
B&D has now developed a specific cyclone-rated garage door that protects homes from wind speeds up to 290km/h.
The B&D Windpanel has been evaluated by the Cyclone Testing Station of James Cook University in Townsville.
The testing facility conducted field investigations following Tropical Cyclone Yasi, which unleashed maximum wind speeds of 225km/h over northern Queensland in 2011, and determined that a large number of garage doors failed during the cyclone.
Its Technical Report on Structural Damage to Buildings* found that of approximately 2000 houses inspected, 29 per cent experienced roller door damage and six per cent had sectional door damage.
James Cook University Cyclone Testing Station development manager Graeme Stark said manufacturers need to develop stronger door systems.
“Large access doors such as garage doors are part of the building envelope and should therefore be designed and installed to resist appropriate wind pressures for their locations – just like roof and wall cladding, windows, house doors and skylights,” said Mr Stark.
“During tropical cyclone Yasi it was observed that some occupants used their cars to brace their garage doors.
“This method really only resisted inward-acting forces but separate bracing systems should be developed to offer resistance to both inward-acting and outward-acting forces.”
B&D Doors has responded to calls for higher-standard garage doors in cyclone-affected regions by developing Windpanel, which derives its additional strength by reinforcing the door structure and providing an additional bracing system which can be manually applied to a door in case of a cyclone warning.
Windpanel uniquely protects against garage door blow-out via a hinge system that connects to a high-wind brace using a deflection bracket.
This system allows a degree of ‘give’ in the panel, enabling it to deflect some outward load before returning to its normal state.
B&D Windpanel is a sectional door available in a wide range of exterior profiles and colours, and can be custom-built in sizes up to 2.4 metres high by 5.5 metres wide.
Windpanel is also compatible with B&D’s Controll-A-Door automatic opener.
Rigorous assessment by James Cook University’s Cyclone Testing Station in 2011 revealed that Windpanel withstood inward and outward strength testing, which has also been independently certified by structural engineers.
“The testing pressures are roughly equivalent to two Land Rovers being driven over the door when laid flat,” said Mr Hardie.
B&D Windpanel installers are specifically trained to properly install the door, ensuring maximum strength and performance.
A home owner can easily install the additional vertical braces in a few minutes, using just a screwdriver.
Once a wind warning passes, the vertical braces can be placed into a dedicated storage bracket.