Turmak Grey Calcarenite is a type of limestone that is commonly used for architectural purposes, including exterior applications. However, its suitability for use in very rainy climates depends on various factors.

Limestone is generally a durable and weather-resistant material, but it can be susceptible to water damage if not properly maintained or if exposed to excessive amounts of moisture over time. In very rainy climates, where the material is consistently exposed to moisture, there may be some considerations to keep in mind.

1. Porosity: Limestone, including Turmak Grey Calcarenite, can have varying degrees of porosity. More porous limestone may absorb more water, which can lead to issues such as efflorescence, staining, or deterioration over time. Therefore, it is important to choose a variety of limestone with a lower level of porosity to minimize these risks.

2. Surface treatments and sealants: Applying surface treatments or sealants to the limestone can help enhance its water resistance and protect it from moisture intrusion. Proper sealing of the material can reduce its porosity, making it more resistant to water damage. Regular maintenance and reapplication of sealants may be necessary to ensure long-term durability.

3. Installation: Proper installation techniques are crucial for any exterior stone application, especially in rainy climates. Adequate drainage systems should be implemented to prevent water accumulation and to direct water away from the surface of the stone. Additionally, correct installation practices such as employing proper mortar joints and appropriate flashing systems can help mitigate water-related issues.

4. Maintenance: Regular maintenance is essential to ensure the longevity and appearance of any exterior stone material. This includes periodic cleaning, removal of any dirt or debris that could trap moisture, and prompt repair of any cracks or damage that may have occurred.

Before using Turmak Grey Calcarenite or any other limestone for exterior applications in a very rainy climate, it is recommended to consult with professionals such as architects or contractors who have experience working with this specific stone. They can advise on the suitability of this material and provide guidance on necessary installation and maintenance practices to ensure its long-term performance in such conditions.