How should a proper masonry chimney cap be constructed?

A proper masonry chimney cap should be constructed with a Portland cement-based mixture that provides an overhang. This design is ideal for several reasons. The Portland cement mixture offers durability and weather resistance, essential qualities for a structure exposed to various environmental conditions such as rain, snow, and extreme temperatures. The overhang is particularly critical as it serves to divert water away from the chimney, preventing moisture from penetrating into the masonry and causing damage over time.

Using an overhanging design helps with water runoff, reducing the potential for deterioration and promoting the longevity of the chimney. This construction method not only protects the masonry itself but also enhances the overall functionality of the chimney by preventing blockages from debris collected in the flue.

Other construction methods mentioned, such as using a wood base or roofing materials, do not provide the necessary durability and water resistance. Wood can easily rot when exposed to moisture, and standard roofing materials are not typically designed to withstand the wear that a chimney cap experiences. Solid brick construction may be strong but lacks the advantageous features of an overhanging design and may not effectively channel water away from the chimney.