Your chimney cap closes the door on water entering your chimney and the damage that it causes. It also keeps out animals such as birds, squirrels, raccoons and other critters that may think your chimney looks like a good summer home. Storms that blow high winds can blow leaves and other debris into your chimney. These are blocked when you have a cap. Blockages that occur from these causes are often the fuel for dangerous chimney fires. The chimney cap (or guard) protects the home of the risk that sparks and airborne embers will land on your roof, causing a fire hazard. Yes, you really do need a chimney cap.
