What effect might excessive porosity in clay shingles result from?

Excessive porosity in clay shingles primarily results from under firing during the manufacturing process. When clay shingles are fired at insufficient temperatures, they do not undergo the necessary chemical transformations that occur during the proper firing process. This failure to reach adequate temperatures can prevent the clay particles from fusing correctly, leading to a shingle that has a higher porosity.

Porosity affects the shingle's durability and water resistance, making it more susceptible to damage from environmental factors such as rain and freeze-thaw cycles. While excessive moisture, poor installation techniques, and environmental exposure can impact the performance of clay shingles, they are not directly linked to the intrinsic porosity characteristic stemming from the manufacturing defects related to under firing. This emphasizes the importance of proper firing in achieving the desired structural integrity and longevity of clay shingles.