What is a chimney cap and what is the purpose of having one? There are many, many homes in the United States that do not have a chimney cap mounted on the chimney, and, on rare occasions, some people never need to install one. It is required by most building codes to have a chimney cap however, and for good reason.
Chimney caps protect the chimney. They not only prevent rain from falling straight down into the flue system, they also keep debris out. Water that falls into the chimney will increase the rate that creosote glazes and tars. This makes removing creosote that much harder. Similarly, any debris brought into the chimney by birds or raccoons is extremely dangerous. This can catch fire up in the middle of the chimney, causing a chimney fire which can really damage the chimney, roof, and even burn the house down.
Stainless steel chimney caps are generally what are most recommended by chimney sweeping professionals. These caps resist rust and are very durable but also affordable. You can usually get yourself a standard sized flue cap for less than two hundred dollars. Never opt for a cap painted black or any other color as this will rust and stain the top of the chimney. These stains are expensive and difficult to remove from the brick and crown after they become present. Copper chimney caps are another option. These caps are very durable as well but are quite expensive and require heavy maintenance to keep them shiny, like a new penny. If copper chimney caps are not carefully maintained they will green into a used penny look.
Caps are fairly easy to install. Generally they come with a few screws and you attach them to the top of the chimney. Chimney professionals will do this service for you at a very low cost. The cost of a stainless steel chimney cap is minute compared to the cost of making a repair after a chimney fire or calling pest control to remove raccoons from your chimney.