Double layer
The double-layer structure, which provides protection from both hail and rain, has become more common in recent years, especially in high-value crops. The system has a hailnet placed on the top of the post, and a rainproof film placed around 50 cm below. It therefore allows to protect independently and at different times from hail and rain. It therefore makes it possible to initially cover the crop with only the net, allowing a better light uptake and temperatures control. In the proximity of the harvest, when the risk of fruits cracking arises, the rainproof film is also laid. The result is an excellent quality of fruits in terms of color, crispness of the pulp and shelf life. The main disadvantage of this system lie in the installation and labor costs, that are significantly higher than those of a simple anti rain system. Structurally, it is recommended to strengthen the system with a double transverse rope: one on top of the posts that is fixed on the post cap, and a second one located under the plastic film and fixed directly to the concrete post with a rope block band. Lengthwise a wire and a rope should be installed. The wire is fixed on the post cap and supports the hail net, while the rope run through the holes of the concrete posts. The hole is important to maximize the surface covered by the rainproof film. It is recommended to use concrete posts that have all 4 edges rounded, in order to limit the possibilities of abrasion of the film in contact with the post itself.