Water leaking into a chimney base (C) Daniel FriedmanWater Leak & Frost Damage to Chimneys & Flues

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Water damage to chimneys & flues:

This article describes water leaks and moisture that damage masonry and metal chimneys and the heating appliances that are connected to them. We list the common sources of water and leaks and we include warnings for inspectors who need to examine equipment as well as the chimney itself when water or moisture leaks are detected.

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Moisture Problems that Damage Chimneys

Water leaking into a chimney base (C) Daniel Friedman

Our photo (page top) shows water pouring into a basement, coming out of the chimney cleanout during a heavy rainstorm. Readers of this article should also see CHIMNEY COLLAPSE RISKS, REPAIRS.

These articles on chimneys and chimney safety provide detailed suggestions describing how to perform a thorough visual inspection of chimneys for safety and other defects. Chimney inspection methods and chimney repair methods are also discussed.

Our photograph at left shows a stunning waterfall flowing out of a "sealed" chimney cleanout in a basement. Lots of roof spillage or surface runoff was entering the base of this chimney.

[Click to enlarge any image]

Moisture is the major cause of chimney corrosion and disintegration in both masonry and metal chimneys. The flue gases are acidic in nature and if allowed to condense and saturate the masonry or joints in metal flues the destructive results will soon be apparent.

Mechanical problems in the construction or settlement after construction and over firing or flue fires will also contribute to the problems.

External moisture enters the chimney through cracked caps, porous masonry, poor mortar joints and improperly designed and installed roof flashings. Internal moisture (condensation) collects in cracked or separated flue tiles, blocked flues and chimney caps.

Masonry chimneys subjected to moisture damage can have efflorescent salt stains, spalled bricks, eroded mortar joints, flaked cracks in the ceramic flue liner and cracked caps.

Metal components of a vent system can have rust and white acid stains at joints, corrosion holes along the bottom of horizontal connectors and corroded chimney cleanout doors at the base of the flue.

Moisture enters a chimney structure from several locations:

Water leaks into a Chimney can Damage the Chimney and the Appliances Connected to It

The result of leaks into a chimney can be unsafe heating equipment as well as costly damage to the chimney, the appliances connected to it, and to the building itself.


Continue reading at CHIMNEY INSPECTION at ROOFTOP or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.




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CHIMNEY DAMAGE, FROST & MOISTURE at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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