The Second Canopy: Double Venting Against Wind Inversion
When an umbrella flips inside out during a storm, this is usually caused by air pressure building up beneath the canopy. Many high-quality models therefore use a double-venting construction, in which a second, smaller canopy sits above the main surface. But how exactly does this system work, and for which situations is it worthwhile? This article explains the structure, function and care of double-vented umbrellas.
Structure and Function of the Double Canopy
A double canopy consists of two overlapping fabric layers, each attached to its own ribs. The lower, larger canopy forms the main surface and keeps the rain out. Above it sits a smaller cap that leaves an opening in the centre. Through this vent, trapped air can escape when wind presses against the umbrella from below. This pressure equalisation prevents the frame from bulging outwards or inverting completely.
Wind Resistance in Numbers
Classic stick umbrellas with a single canopy withstand wind speeds of up to approximately 50 kilometres per hour before the frame gives way. Models with double canopies achieve values of 70 to 90 kilometres per hour, depending on the number of ribs and quality of the frame. The following features are decisive:
- At least eight, preferably ten or twelve ribs for stable support
- Fibreglass or carbon fibre ribs that bend rather than break
- Reinforced seams at the connection point between both layers
- Span between 100 and 120 centimetres for adequate protection without excessive wind resistance
Material Selection for Both Layers
The lower canopy usually consists of dense polyester or pongee fabric with a water-repellent coating. The upper layer can be made from the same material or from lighter fabric, as it only needs to direct the airflow. High-quality Umbrellas use the same fabric for both layers so that the colouring remains uniform and no stains occur due to different drying times. In models with contrasting colours, the upper cap provides a visible accent.
Use in Changeable Weather
Double-vented umbrellas are particularly suitable for regions with frequent gusts or for people who spend a lot of time outdoors. The higher weight, usually between 450 and 600 grams, becomes noticeable during prolonged carrying. In return, the construction offers security when strong wind suddenly picks up. Many Men's umbrellas use this system, as they already provide more stability as stick umbrellas than compact pocket versions.
Care After Use
After use, you should allow both layers to dry completely before closing the umbrella. To do this, open it in a sheltered location and leave it standing for at least two hours. Moisture trapped between the layers can lead to mildew or mould. Regularly check the seams on the upper cap, as these are subjected to greater stress from wind loading than with simple canopies.
Automatic or Manual Opening
Double-vented models are available both with automatic and manual opening mechanisms. The mechanism must work synchronously for both layers to prevent creases from forming. Automatic versions weigh approximately 50 to 80 grams more due to the additional spring mechanism, but open at the press of a button. Manual variants allow finer control when opening and are generally more durable, as fewer moving parts are installed.
Related items: Jewellery, Bags and accessories, Pocket umbrellas. The complete range: Umbrellas.
Related categories: Jewellery, Bags and accessories, Pocket umbrellas. The full range: Umbrellas.
Read more: Transparent Umbrellas: Visibility, Safety and Cleaning, Steel or Fibreglass Frame: What Withstands Storms, Handmade or Mass-Produced: How to Recognise Quality Craftsmanship, Combining Umbrella and Bag: Coordinating Material and Colour, Umbrellas as Gifts: What Often Goes Wrong