Water may be essential for human life but it can be damaging to a masonry chimney. A chimney is constantly exposed to weather elements including rain, snow, and humidity. If this moisture is in contact for a prolonged period, the chimney will deteriorate in an accelerated manner. Most materials that comprise a masonry chimney are adversely affected by the penetration of or direct contact with water.
Brick, concrete, and mortar are commonly used to constructed masonry chimneys. When moisture penetrates these materials, it may periodically freeze and expand during changes in the weather. This process creates stress on the chimney, causing it to deteriorate. Even the metal components of a masonry chimney, which typically include cast iron and steel, can be adversely affected through rusting.
A chimney made from stone, which does not typically deteriorate due to water, may suffer because it contains a large amount of mortar. Water penetrating a chimney can stain the exterior, decay exterior mortar, and cause the chimney structure to tilt or collapse. Water can also damage the interior of a masonry chimney by rusting the damper, deteriorating the firebox, and cracking or deteriorating the flue liner.
Water penetration may extend to the interior of the home and include stained walls and ceilings, ruined wall coverings, and rotting wood adjacent to the chimney and fireplace. Water penetration can even deteriorate a central heating system, costing thousands of dollars in repairs or replacement. If water mixes with the creosote on chimney walls, an unpleasant odor will permeate the home.
The least expensive way to prevent this type of water damage is to have a chimney cap installed. A professional can perform this job at a very reasonable price. Water will stay out of the chimney and the cap will also prevent fireplace embers from landing on the roof or another combustible surface where they can cause a fire.