Animals frequently make their nests close to or inside chimney flues. These nests can block the path for what usually goes out of the top of the chimney. Typically smoke and gases from the fire below will exit the home through the chimney. With large squirrel or bird nests in the way, these harmful gases will end up backed up into the rooms of your home.
Rain, snow, and ice can create problems for your chimney if they are allowed in the chimney flue. Moisture causes deterioration problems within the structure of your chimney. The back and forth of freezing and melting of ice is especially hard on the masonry chimney walls, chimney crown and chimney liner. This could lead to costly repairs. Therefore, it is best to not allow the excess moisture into the chimney in the first place by diverting the elements away with a cap that is right for your chimney.
Burning embers from the fire below get sent up and out of the chimney along with the burning gases. These pieces of the fire can escape out of the top of the chimney and can cause damage to your roof and even possibly start a fire . These problems are entirely avoidable with the addition of a chimney cap and spark guard.