What is the best material for a masonry chimney crown?

The best material for a masonry chimney crown is concrete. This choice is preferred because concrete is strong, durable, and can withstand the elements much better than the other materials listed. A well-constructed concrete crown provides a watertight seal that prevents moisture from penetrating into the chimney structure, which can lead to deterioration and other related issues such as mold growth or structural damage over time.

Concrete also offers the ability to be molded and sloped effectively, allowing for proper drainage away from the chimney. This is critical in preventing water from pooling on the surface, which can further contribute to damage.

In contrast, materials like brick may not provide adequate waterproofing due to their porous nature, and over time, bricks can absorb moisture, leading to erosion and damage. Wood, being organic, is prone to rot and does not offer the necessary durability or resistance to heat. Metal, while sometimes used in chimney caps, does not provide the same level of durability or thermal management as concrete for the crown itself. Overall, concrete stands out as the most effective choice, combining resilience and practicality for chimney crown applications.