The chimney is one of the most taken-for-granted and neglected parts of a 
home. Because it is taken for granted, it does not receive the attention and maintenance that most other household items do. Despite indifference, abuse and neglect chimneys still perform their job reasonably well and as odd as it may seem, water causes more damage to masonry chimneys than fire.
Chimneys are not those passive black holes that most people assume them to be. They do perform several vital functions, and their simple appearance misrepresents their complex construction and performance requirements. A chimney deteriorated by 
constant exposure to the weather can be a potential safety hazard. Weather-damaged lining systems, flue obstructions and loose masonry materials all present a threat to residents. Regular chimney maintenance is essential to prevent damage, deterioration and future high-cost chimney repairs.
Masonry chimneys are constructed of a variety of masonry and metal materials. All masonry chimneys contain a combination of, or even all of the following materials: brick, mortar, concrete, concrete block, stone, flue tile, steel and cast iron. Most of these components are adversely affected by direct contact with water or water penetration.
Keep in mind that all masonry constructed chimney materials, except stone, will suffer accelerated deterioration as a result of prolonged contact with 
water. Masonry materials deteriorate quickly when exposed to the freeze/thaw conditions in the form of spalled brick. Spalling is a process in which moisture that has penetrated the brick freezes and expands causing undue stress. Water in the chimney also causes rust in steel and cast iron, weakening or destroying the metal parts.
Water penetration not only can cause damage to the exterior, it can cause interior damage to your home as well. These can include the following:
• Rusted or damaged damper assemblies
• Deteriorated/damaged metal or masonry firebox assemblies
• Rusted accessories, fire screens and glass doors
• Water stained walls and ceilings and/or ruined/damaged wall coverings
• Stained chimney exterior
• Decayed/damaged exterior mortar
• Cracked or deteriorated flue lining system
• Tilted, collapsed or broken chimney structures
• Chimney settlement
I will continue this basic tutorial on chimneys in part two of the series when I address chimney crowns.
The Complete Home Inspections Team - Brentwood, TN 37027
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