Wenatchee Home Inspector
Fear of Crack- Fireplace Chimney Flues Tiles
One very common and potentially dangerous situation is a cracked chimney flue liner. During a home inspection one the items I am looking for are cracked tiles. The signs can often be subtle or even hidden behind creostoe that may have built up on the flue liner.
The chimney flue is the narrow passageway in which the combustion byproducts of the fire are removed. The construction and operation of the entire chimney system needs a proper design and function so that smoke and toxic fumes exit the chimeny and home.
The main purpose of the flue liner is to protec the combustible parts of the home. Escaping heat from the chimney can lead to pyrolysis. Pyrolysis can decompose materials within reach simply with heat and oxygen and actually start a fire without direct contact to flame.
There are two main two reasons that pyrolysis occurs accidently in homes and starts house fires. The first is because your solid fuel stove, wood burning stove, or fireplace was installed incorrectly. The unit is too close to combustible materials such as wood trim, the edges of sheathing materials, or wood siding or flooring, and it is not code compliant. The second reason is there is a crack or damage in your chimney liner or fireplace. Cracks allow heat and oxygen to escape and come into contact with combustible materials and heat and oxygen are all that is required for pyrolysis to occur.
The National Fire Protection Association did a test where they placed a stack of 1/8 inch thick fiberboards close to a wood burning stove and it only took 4 days for the fiberboards to ignite without direct contact to flame.
The most common type of flue liner built in homes across the United States is a clay tile flue liner. This is the case because clay tiles do an effective job of protecting the home for an average of about 25 years and yet they are inexpensive materials preferred by the vast majority of builders.
Over time, clay tiles begin to deteriorate. The most cost-effective solution is to reline the chimney and better yet installed an insert which is far more energy efficient. The cost to replace clay tiles is very expensive and involves partially tearing down the chimney in order to replace the damaged clay tiles.
Some insurance companies may pay for the cost of an insert and liner so it would be good to check with your insurance company if this condition is found.
Fireplace and the associated chimney should be inspected and cleaned annually.
"It is not light that we need, but fire; it is not the gentle shower, but thunder.
We need the storm, the whirlwind, and the earthquake."
If you find any errors or have additional information that would expand on any code, building standards or manufacturer requirements please let me know.
NCW Home Inspections, LLC is a Licensed Washington State Home Inspection service located in Wenatchee Washington serving Chelan County, Douglas County, Kittitas County, Okanogan County and Grant County Washington and the cities of Wenatchee, Leavenworth, Cashmere, Oroville, Cle Elum, East Wenatchee, Quincy and many more…
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Instructor- Fundamentals of Home Inspection- Bellingham Technical College
WA Home Inspector Advisory Licensing Board