Maximum hail protection... to keep your roof dry
Thunderstorms accompanied by heavy rain and hail are no longer exceptional occurrences, especially during the summer months. They are now more frequent throughout Europe. Hailstones, up to 5 cm in diameter, can cause considerable damage to building envelopes, especially roofs. However, not all roofs can emerge from hailstorms unscathed. That's why we recommend incorporating hail protection directly under the roof covering, using a high-quality roof underlay. The roof underlay protects the roof structure and insulation from the elements, and acts as a second layer of waterproofing in the event of damage to the roof covering, e.g. due to storms or hail. In this case, roof underlayments that have been tested for their hail resistance - recognizable by the hail-resistance class distinction - score points.
Maximum hail protection thanks to HW5* hail resistance class
The "Protection against Natural Hazards" inspection body of the Swiss Association of Cantonal Fire Insurance Institutions (VKF) has tested pro clima roof underlayments. For the test, the screen was unrolled on a wood-fibre insulating panel and then bombarded with hailstones. The screen is then visually inspected for cracks and tested for watertightness using a water column. Watertightness must still exist for the test to be validated. pro clima screens have passed the tests for resistance class HW5*, being bombarded by the largest ice balls (diameter 50 mm) at a speed of 110 km/h.
Hail resistance
Hail resistance is the term used in European test method EN 13583. This standard describes a test method comparable to the Swiss test, in which a wall is bombarded with a polyamide ball (PA 6.6) 40 mm in diameter and 38.5 g in mass. This shot is evaluated at the "minimum damage velocity vd in m/s". In other words, this method gives the maximum firing speed for which the wall still remains watertight and undamaged/unperforated (of the screen).
* HW: "Hagelwiderstandsklasse" in German, which translates into "hail resistance class" in english
In brief
pro clima roof underlayments offer essential additional protection: even when tiles break under the impact of hailstones, the underlayments keep the wall dry.
What's more, pro clima roof underlayments can be exposed to the elements for up to 6 months.