The international standard for waterproof rate of WPC wall cladding panels can vary depending on the specific testing method and standards applied. However, one common benchmark used is the International Protection (IP) rating system defined by the International Electrotechnical Commission (IEC) in IEC 60529.

The IP rating consists of two digits, with each digit representing a different level of protection against solids and liquids, respectively. The second digit, which pertains to liquid ingress protection, is most relevant when considering the waterproof rate of WPC wall cladding panels.

Here are some common IP ratings related to waterproofing:

• IPX0: No special protection against water.
• IPX1: Water dripping vertically onto the product has no harmful effect.
• IPX2: Water dripping at an angle of up to 15 degrees from vertical has no harmful effect.
• IPX3: Water spraying up to 60 degrees from vertical has no harmful effect.
• IPX4: Water splashing from any direction has no harmful effect.
• IPX5: Water jets projected by a nozzle from any direction have no harmful effect.
• IPX6: High-pressure water jets from any direction have no harmful effect.
• IPX7: Immersion in water up to 1 meter of depth for a specified duration has no harmful effect.
• IPX8: Continuous immersion in water under conditions specified by the manufacturer.

To determine the appropriate waterproof rate for WPC wall cladding panels, it is advisable to consult the specific IP rating or applicable waterproofing tests provided by the manufacturer or referring to the building codes and regulations in your country or region.