Chimney Tops are most exposed to rain, wind, sun and temperature variations, for being the highest part of the structure.

The cement cap on top of the chimney is the most important part of the chimney because this is the first part of the chimney to deteriorate.

A worn or broken cement cap can allow water to invade into the bricks and interior of the chimney, where there is no sunlight or air to dissipate the moisture, for several years before the owner will notice any damage; which by then will result in many open mortar joints and/or spalling brick, thus inviting in more water and deterioration.

I recommend replacing the cement cap every 20 years and applying sealer every 5 years.

Excess Water Erodes Masonry:

Avoid future repairs by maintaining your masonry in its vulnerable areas where moisture is abundant.