This is quite a difficult question to answer as there are so many factors involved with wind in the real world, gusting, steady and swirling winds all create different effects. Most higher specification awnings will have a tested and certified wind rating based on km/h or the Beaufort scale but of course no one is ever really monitoring the wind speed in their back garden or patio to make a judgement on this…
Generally, the rule of thumb is that the larger the fabric awning is then the lower the wind rating will be, and consequently more measures need to be put in place to protect and control the awning when it becomes windy.
The difference between a ‘self-supporting’ retractable fabric awning and a ‘supported’ fabric awning or pergola (which is technically a canopy) is enormous in terms of its resistance to wind.
When the front of a projecting awning is supported as well as the back with tracks down the side as well holding the fabric then the forces are spread far more evenly which also helps in the fixing of the awning against the wall structure taking pressure off this area
When we are asked about retractable awnings, and it is understood the awning is only for use on calm and hot sunny days for protection from the heat and UV rays, then all is fine. However, when large fabric awnings are used on commercial premises and maybe the awning is not managed 24 hours a day, obvious problems may be encountered. The simplest way to deal with a self-supported retractable awning and its vulnerability to wind is to always ensure the awning has a wind sensor or motion sensor fitted which will retract the awning completely in windy conditions. This of course is only possible with an electric awning, but by definition a large retractable awning should be electrically operated for ease of operation and control. The wind speeds that most self-supported awnings are tested to is about 20 – 25 miles per hour but that does assume a steady wind and not a buffeting irregular wind which can be far more dangerous. More commonly used now are the motion sensors as they detect movement in the awning rather than the wind speed which can be irrelevant.
For larger retractable fabric awnings, or pergola systems, such as the Markilux Pergola or the Weinor Plaza, the fabric cover is held in place on all 4 sides, and because the structure that the fabric is operated in is supported by posts at the front the wind speed resistance is far higher. These systems are ideal in more exposed locations or where a large terrace needs covering, and a decent level of rain cover is also required. They do not need such steep pitching for the cover and because they are supported on all 4 sides the rainfall will not be such a problem when there is a cloud burst and instant heavier weight on the cover.
In areas where there is a definite problem with exposure to winds and protection from rain is required you should be looking at systems like the Weinor Pergotex or any of the Gibus retractable roof systems. Much tougher vinyl fabrics are used along with reinforced struts operated within sturdy aluminium framework systems also with built in rainwater guttering. The fabric cover when extended is super sturdy and the framework is strong enough to have additional fixed or retractable products fitted to the front and sides. This controls the wind extremely well for domestic or commercial applications.
The wind is probably a bigger enemy of the traditional retractable awning than anything else and although you may ask yourself why would you be sitting outside in the wind anyway, there is usually a prevailing wind in every garden or terrace area, particularly near the coast or on hill top locations. Having a system with an enhanced protection from at least one side will enable far more use in windier conditions so the demand for systems to use in strong winds are common requests now. Specify the main canopy cover properly in the first place and then you won’t worry when the all too regular stormy conditions arrive.
Of course, the ultimate system for all year round protection from rain, no problems in the wind and also offers a solution on the hottest days is the glass veranda with optional fabric blind system, either underneath or above the glass roof. See our Glass Veranda page >