A chimney crown is a vital, yet often overlooked, component in masonry chimney construction. The chimney crown is located at the top of a chimney and is designed to keep water from entering it. Not nearly as glamorous as its royal name implies, a chimney crown is a concrete, mortar, or stone covering that seals the top of the chimney around the flue and diverts rainwater. A gap between the flue and the crown allows for expansion. In addition to the chimney crown, a chimney cap or rain cover may be used to cover the flue and prevent rain from pouring in.
While some crowns and caps have decorative elements, their primary function is to keep water out of a chimney. This is essential in maintaining the chimney’s structural integrity. Water damage can manifest into brick and mortar cracks, spalling, deterioration, efflorescence, organic growth, and other masonry problems. These problems in turn cause other problems such as interior water leaks, excessive interior humidity, fire hazards, or even a chimney collapse.
Unfortunately, some chimney crowns are poorly designed from the beginning. For example, many cement chimney caps in Chicago lack an overhang to properly divert the water. Brick chimneys are commonly crowned with the same mortar used in the brickwork or have what’s known as a “cement wash” crown. While this type of crown serves its purpose at first, the mortar commonly used is not designed to withstand the direct impact of the elements. Chips, cracks, deterioration, and shrinkage commonly occur, allowing water inside the chimney. In addition, chimney crowns should protrude over the edge of the chimney with a “drip edge” to divert water away from the chimney’s sides.
Chicago Brick Company offers complete chimney crown restoration, repair, and replacement services. We highly recommend limestone chimney crowns which are prefabricated out of natural limestone. Limestone chimney crowns are better and more durable than traditional mortar or cement-based chimney crowns. Limestone crowns are manufactured to exacting specifications and professionally installed, allowing for long-lasting protection and proper water diversion.
Is your chimney crown giving you a headache? Contact us today for professional chimney crown repair in Chicago.