By Ashley Eldridge
Director of Education The Chimney Safety Institute of America ( CSIA )
Dead in the Water :
Proper Care and Maintenance of Chimneys
I n a hypothetical list of the most taken-for-granted parts of an apartment community , it ’ s a guarantee that chimneys are at or near the top .
Chimneys tend to receive neither the attention nor the concern usually accorded other service systems . It ’ s a safe assumption that because a chimney tends to perform its function reasonably well — even when abused or neglected — this atmosphere of indifference persists .
Chimneys are far from the passive black holes that most assume . They perform several vital functions , and their simple appearance misrepresents their complex construction and performance requirements . A chimney deteriorated by constant exposure to 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 address damage , deterioration and future high-cost repairs .
Masonry and Water Don ’ t Mix
A masonry chimney is constructed with mortar and of a variety of materials , including brick , concrete , concrete block , stone , flue tile , steel and cast iron . All masonry chimneys contain combinations of , or possibly all of , these materials , most of which are adversely affected by direct contact with water or water penetration .
All masonry chimney construction materials ( with the exception of stone ) will suffer accelerated deterioration as a result of prolonged contact with water . Masonry materials deteriorate quickly when exposed to the freeze / thaw process , by which moisture that has penetrated the materials periodically freezes and expands , causing undue stress . Water in the chimney also causes rust in steel and cast iron , weakening or destroying the metal parts .
With regard to stone , although most types are unaffected by water penetration , large amounts of mortar are required to properly bond the pieces together . Therefore , a stone chimney — just like a brick chimney — should be protected from the effects of water penetration .
In addition , when water mixes with creosote in a wood-burning chimney system , it will generate a highly disagreeable odor
that can permeate a common area or individual unit . Holding Back the Waters
When it comes to water-damage prevention , chimney caps , also called “ rain covers ,” are probably the most inexpensive preventive measure that one can employ to prevent water penetration and damage to the chimney . Chimney caps have long been recognized as an important chimney safety and damage prevention component . Underwriters Laboratories ( UL ) specifies that any chimney lining system that is to be listed to their test standard must include a chimney cap .
Chimneys have one or more large openings ( flues ) at the top that can collect rainwater and funnel it directly to the chimney interior . A common-sized flue has the potential to allow large amounts of rain or snow into the chimney in a single winter where freeze / thaw cycles are common .
Chimney caps also provide other benefits . A strong , well-designed cap will prevent birds and animals from entering and nesting . Caps also function as spark arrestors , preventing sparks from landing on the roof or other nearby combustible material .
A chimney cap should be easily removable to facilitate inspection and cleaning . For a long and effective service lifetime , a cap should be constructed of sturdy , durable and corrosion-resistant material such as stainless steel . Caps may be designed to cover a single flue , multiple flues , a large portion of the chimney or the entire chimney top . A full coverage chimney cap usually requires a larger initial investment ; however , it is probably the best investment for long-term protection because of its ability to safeguard the entire chimney crown .
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