A high quality chimney cap can reduce long-term maintenance costs on your chimney, improve the safety of your home and improve the external appearance of your house, all for a relatively small investment. Chimney caps are inexpensive and easy to install, so this final element in your chimney system is not something you should neglect.
You can choose from a wide variety of chimney caps made from several different materials. The chimney cap you choose will be determined by your unique chimney configuration and the amount of money you want to spend to make your chimney safer and more attractive.
The most common materials that chimney caps are manufactured from include painted steel, aluminum, stainless steel and copper. Steel and aluminum chimney caps are inexpensive, but they might not be the best choice for your chimney since they will be more likely to rust and corrode when they are subjected to weather extremes and the harsh compounds that are carried in smoke and other combustion gases.
For just a little more money, you can buy a stainless steel chimney cap that will resist corrosion and give you many years of service. If it will enhance your home’s décor, you can also buy a copper chimney cap, which looks elegant and also resists corrosion with proper maintenance.
Besides deciding on what material you want your chimney cap to be made of, you also need to determine what chimney cap design is right for your house. This will be determined by factors including the number of flues that share your chimney, the type of chimney liner you have, the shape of the flue where it protrudes above the chimney, and whether you expect your chimney cap to improve your chimney’s draft.
For a simple brick chimney with a single chimney liner protruding from the top, a standard single-flue chimney cap will serve you well. These chimney caps are usually made with a solid top and screened sides. They fit over the outside of the flue tile and are secured in place with screws. The screen is designed to arrest sparks coming up the chimney and to prevent small animals and trash from falling down the flue.
If your chimney has a round metal liner inside the flue, you can get a cap that is designed to attach to the round top of the liner rather to fit over the clay tile liner top. Consult with the manufacturer’s specifications for the liner and any appliances you vent through the liner to see if they require any particular cap design for effective operation.
Some chimneys carry more than one flue, with two or more tile liners protruding above the chimney crown. If there is sufficient space between the flues, you can cap them individually with single-flue caps, or if space is tight or you prefer the look, you can buy a chimney cap that is designed to cover multiple flues. These also fit down over the flue tiles and are held in place with screws.
There are specialty chimney caps available for some situations. Some chimney caps are designed to improve chimney draft and prevent down-drafts on windy days by creating a slight vacuum between the chimney cap and the top of the flue which pulls smoke and gases upward. You can get special caps that include electric exhaust fans if you have a poorly drafting chimney that needs active mechanical help to draw well. You can also install a top-seal damper, which is a device that seals your chimney top when the flue is not in use to keep cold air out of the house, but is raised with a lever inside the house to open the flue and double as a chimney cap allowing smoke to exit the chimney.
A properly selected chimney cap can improve your home’s appearance, make your chimney system safer, reduce maintenance costs and enhance your energy efficiency, all for a very reasonable one-time investment. If you choose your chimney cap carefully, it will pay for itself many times over by extending the life of your chimney, increasing your fuel efficiency, and improving the external appearance of your home.