If you think about it, many things have the perfect counterpart to protect them from rain. Convertibles have tops, houses have roofs, pools have covers, and chimneys have caps! All of these items' counterparts are essential to the functioning of that item. If a convertible had no top you could never take it out if there was a chance of rain. Your things would get soaked if there wasn't a roof on your house, and your pool would get damaged over the winter months without a cover. Similarly, a crown tops off a chimney to strengthen it and prevent brick from being damaged at the very top of the chimney which is most exposed to the elements.

Since the crown is exposed to the elements at a higher rate than the rest of the chimney, cracks frequently occur. Once cracks occur in the crown, they will continue to grow and deepen as precipitation enters them in the form of vapors and actually liquid water. These become extremely problematic, lessening the integrity of your chimney and leading to its eventual deterioration.

Cracks in the crown must be treated in a timely manner with a sealant to prevent them from worsening and jeopardizing the strength and life of your chimney. Various treatments exist, but siloxane treatments have the best life and protection and often can be stored for a few years to re-treat and treat any new cracks that may develop over time. ChimneySaver products such as CrownCoat have been tested and proven over time to give chimneys the protection they require. When making repairs here in Cincinnati, my service technicians use ChimneySaver products because they are specially formulated to withstand the harsh elements chimneys are exposed to since they have no coverage from any surrounding forms. The chimney projects above the roofline, making it a perfect target for damage from the elements, so no ordinary brick and masonry sealant is going to provide the needed protection.

Crowns absolutely must be constructed properly to begin with. As a matter of fact, mortar crowns are in no way recommended. Mortar is what holds brick together,but it is not the proper material for constructing a crown. Concrete, made with Protland cement, stones, and sand, is what is recommended to construct a crown from. The stones make for strength that cannot be matched by mortar alone. The concrete will prevent the elements from wearing down more and more on the chimney itself, seeing that the crown is really protecting the top of the chimney in general.