What aspect of lead makes it a common choice for flashings against masonry?

Lead is a common choice for flashings against masonry primarily due to its malleability and ability to retain its shape. Malleability refers to the metal's capacity to be easily shaped or formed without breaking, making it ideal for applications where it needs to conform closely to the surfaces it is protecting. When working with masonry, which often has uneven surfaces or requires precise angles and curves, lead can be manipulated to create a tight seal, preventing water infiltration and damage.

Additionally, its retention of shape means that once shaped, lead can provide long-lasting protection without the risk of cracking or degrading over time, which is essential for maintaining the integrity of the flashing. This durability and adaptability in form are key characteristics that contribute to its effectiveness in roofing applications involving masonry, ensuring a reliable barrier against moisture.