The main and probably the most important function of a chimney crowns is to safeguard the chimney body from damage due to harsh weather exposure. Properly installed chimney crowns can achieve this by lengthening above the original walls of the chimney. This is achieved by the chimney crowns being attached to metal or rigid steel brackets which are then fixed directly to the top of the chimney. No mortar is used in the construction of chimney crowns as they are simply a sheet of metal or iron that is bent around the chimney body with bent sides. Once the chimney crowns have been formed it is then fastened to the roof of the house using stainless steel flashing. Chimney caps are then used to cover up chimney crowns.
A lot of times chimney crowns will be constructed from masonry bricks which are then painted a brick red color. Other times brick may be used but it must be the only color provided as the bricks used are not easily accessible and will usually have to be bought. Masonite is the most commonly used material for construction of chimney crowns. Other materials such as clay tiles may also be used. These options are good as they all provide a similar appearance but there are differences between the way the mortar is built, how long it is actually employed for and the final appearance of the chimney crowns
So what is a chimney crown? A chimney cap is actually the name given to the chimney crown, and a chimney crown is what provides that ornamental look at the top of the chimney, just like a classical Greek or Egyptian building. In the case of a typical English house a chimney crown is probably the most recognizable part of any fireplace. It may even be considered a point of interest in itself!
Basically chimney crowns are constructed from either masonry or cast-in-place concrete chimney crowns, but the actual look depends on your preferences and the available designs from local contractors. In the case of masonry chimney crowns the finished product will likely be a solid brick wall with mortar joints and a cap shaped like a traditional fireplace. It is important to note that the concrete chimney crown will probably need to be replaced every few years as it is subject to deterioration from the weather and weathering from the rays of the sun.
Cast-in-place concrete chimney crowns (also known as solid brick chimney crowns) are built in a similar fashion to the masonry chimney system, though this time the brick is actually left in place during the construction process. To construct these chimney crowns, the floor of the chimney will first be covered with plywood and a waterproof membrane. Then the top masonry chimney crown will be placed over the plywood cover and concrete will be poured into the joints between the bricks. This will set and remain until it has set and completely hardened. At this time a cover of plastic will be laid over the top to protect it from the elements. Finally, a firebrick cap will be used to complete the exterior look of the chimney crown.
To keep chimney crowns looking attractive they should be inspected on an annual basis by a certified chimney inspector. The inspector will look for signs of deterioration such as cracking mortar joints, discoloration and water leaks. Signs of damage can be repaired or replaced, but the cost can be expensive. Also, if a crack or other damage should occur during the year, the cost of repair and replacement can be greater than the cost of installing a chimney crown.