Your chimney cap closes the door on excess water entering your chimney and the damage that it causes. It also keeps out birds, squirrels, raccoons and other critters that may think your chimney looks like a good summer home. Leaves and other debris that storms and high winds can also blow into your chimney, but are blocked by a cap.
Blockages that occur from these causes are often the fuel for dangerous chimney fires. The chimney cap (or guard) protects the home from pests and debris, and reduces the risk that sparks or airborne embers will land on your roof and cause a fire hazard.