The best investment you can make to protect your chimney is a good quality chimney cap. A chimney cap prevents entry of rain and animals and helps contain sparks. Chimney caps can also help solve certain chimney performance problems.
The number one cause of damage to chimneys is rain and weather. Rain is absorbed into the bricks and mortar and weather changes cause expansion and contraction which deteriorates the masonry, compromising your chimney's structural stability.
BIRDS & ANIMALS
Birds and animals are attracted to chimneys. Chimneys offer a nice, tall place to live with secure protection. However, animal and bird nests are highly flammable, baby birds make incessant noises that will nearly drive you mad, and if the critter can't exit through the top of the chimney, she and her babies will try and exit through the bottom - right into YOUR house! Raccoons and squirrels can get into the house and cause thousands of dollars in damage to furnishings, rugs, curtains and everything in reach in their desperate attempt to escape from your home. They also harbor lice, fleas, rabies and other diseases that can put your family at risk.
Most folks figure that the baby critters will grow up and leave the nest, exit the chimney top, and then you're safe to use the chimney. Not true! First of all, far too many babies cannot escape the chimney and will die in there, creating horrible odors and maggot infestations. Second, the remaining nesting materials can block the chimney so that fumes and smoke cannot escape, as well as providing fuel for a raging chimney fire.
Keep in mind that migratory birds are considered endangered and cannot be removed by law. Chimney sweeps are not even allowed to remove a nest that's being used by chimney swifts (pictured right) for example. After the animal or bird evacuates your chimney, on its own or through forced eviction, you must have the chimney cleaned to remove the nesting materials, then install a chimney cap to prevent their return. The screening built into the cap is carefully designed to allow proper drafting yet keep out uninvited wildlife guests.
SPARK ARRESTORS & PERFORMANCE PROBLEMS
A good chimney cap also includes a screen that helps control sparks. On windy days, chimney draft can be affected and if sparks exit the chimney they can ignite nearby trees, leaves and other flammables. If your home is located within a wooded area, a chimney cap with a spark arrestor is strongly recommended.
*This article used with permission from THE FIREPLACE CHANNEL - Copyright 2006