Masonry is used to construct a Class A vent.

• A. True
• B. False
• C. Cannot determine
• D. Depends on construction

Answer: (A)

Class A vents are built to carry hot combustion gases while staying noncombustible and able to withstand high temperatures. Masonry fits that requirement because brick or stone is inherently noncombustible and can be constructed to contain the heat safely, especially when the interior is lined with a suitable flue liner (such as clay tile or a listed metal liner). This lining protects the masonry from heat and corrosion and ensures proper venting. So masonry is a valid material for a Class A vent. There are also listed metal factory-built Class A vents, but masonry remains an acceptable option.