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CHIMNEY INSPECTION DIAGNOSIS REPAIR
BACKDRAFTING HEATING EQUIPMENT
CARBON MONOXIDE - CO
CHIMNEY COMPONENT DEFINITIONS
CHIMNEY FIRE ACTION / PREVENTION
COMBUSTION GASES & PARTICLE HAZARDS
COMBUSTION PRODUCTS & IAQ
FLAME COLOR, BLUE vs YELLOW COMBUSTION
HEATING SYSTEM INSPECTION
HOME HEATING SAFETY
ODORS GASES SMELLS, DIAGNOSIS & CURE
SAFETY RECALLS CHIMNEYS VENTS HEATERS
STAIN DIAGNOSIS on BUILDING EXTERIORS
WOOD, COAL STOVES & FIREPLACES
WOOD STOVE SAFETY
How to build or inspect a wood-framed chimney chase: this article describes wood-enclosed metal chimneys, how a chimney chase should be constructed, and how those structures can be inspected for leaks, damage, or unsafe conditions. This article describes how to perform a visual inspection of wood framed chimney chases used to enclose factory-built metal chimneys for safety and other defects. Chimney inspection methods and chimney repair methods are also discussed.
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Chimney Chase Construction SNAFUs to Avoid
Our photographs show a typical wood-framed chimney chase constructed to house an insulated metal chimney and/or a Type-B gas vent. The photo at above left shows an incomplete chimney chase with poor workmanship - incomplete installation of housewrap, missing chimney flashing, and who knows what at the chimney top.
Our photo at above right shows vinyl siding has fallen off of the chimney chase, permitting leaks into the structure. Below we show common leaky conditions at the top of a wood-framed chimney enclosure.
The most common defect we find at wood-framed chimney chase ways is an improperly-constructed top flashing that is not sloped to drain properly (above left). Often people try to fix a leak at the the chimney top by smearing on roofing mastic (above right). We find that this is not a durable repair.
A close-look at the top of a mastic-coated wood-framed chimney chase may show that the top is still concave, sloping in towards the chimneys and that the combination of heat and sunlight has dried and cracked the sealant. (Photos above).
The result is leaks inside of the chimney chaseway where water may lead to a damaged and unsafe fireplace insert or heating appliance, rot, and insect damage.
Our photo (left) shows how the interior of a wood-framed chimney chaseway may be constructed using common framing lumber and drywall. In this particular chase no chimney has (yet) been installed.
But leaks at the top of this structure wet the drywall sides leading to a (hard to see) mold contamination.
Watch out: before buying materials and starting to hammer away at constructing a chimney chase for your home, be sure to check with your local building code officials.
Common Specifications & Construction Details for a Wood-Framed Chimney Chase
Our photo (left) shows the remains of a metal chimney passing through the framed chimney chase enclosure as it passed through the first floor of occupied space in a building that suffered severe damage from a chimney chase fire. The factory-built insulated metal chimney was venting an oil fired heating boiler.
How to Identify Common Leak points & Hazards at Wood Framed Chimney Chases
Details of this topic have been moved to a new article found at CHIMNEY SHROUDS. Excerpts are just below.
A "Chimney Crown" as popularly used in the fireplace industry may refer to a decorative top shroud installed atop a wood-framed chimney chase, as illustrated here. Steve Werner, a home inspector and chimney shroud installer with Chimney King , a custom chimney "crown" designer in Gurnee IL, provided us with the following wood framed chimney chase top pans along with comments.
At above right we can see the newly fabricated chimney chase top pan that has been corbelled out to increase its footprint or horizontal size dimensions to accommodate a decorative top shroud.
Mr. Werner continues:
In the fireplace industry we use the term “chase pans” for the covering at the top of a wood framed chimney chase.
Our company, ChimneyKing, has bought lots of fireplaces, pipe, and made many decorative shrouds for testing in these labs to assure that our products are labeled and safe.
Contributor & technical review: Stephen Werner General Manager Chimney King, LLC P.O. Box 8 Gurnee, IL 60031 Corporate (847) 244-8860 Fax (847) 244-8694 Email: firstname.lastname@example.org
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