InterNACHI Fireplaces, Chimneys & Solid Fuel Appliances 2 — Questions and Answers
Question 1: Spalling observed on a masonry chimney exterior refers to:
- Horizontal cracks forming along mortar joints between brick courses
- Flaking or breaking off of the face of brick or stone surfaces (Correct answer)
- White mineral deposits on the chimney surface
- Separation of the chimney from the main structure at the foundation
Correct answer: Flaking or breaking off of the face of brick or stone surfaces
Spalling is the physical breaking, chipping, or flaking of masonry surfaces, typically caused by freeze-thaw cycles forcing absorbed moisture to expand inside the material.
Question 2: Efflorescence on a chimney indicates:
- Creosote migration through the masonry from the flue
- Water is moving through the masonry and depositing minerals on the surface (Correct answer)
- Spalling of the outer brick face due to freeze-thaw cycles
- Thermal expansion cracks forming near the chimney cap
Correct answer: Water is moving through the masonry and depositing minerals on the surface
Efflorescence is a white crystalline deposit left on masonry surfaces when water migrates through the material and carries soluble salts to the exterior as it evaporates.
Question 3: What is the function of the smoke shelf inside a masonry fireplace?
- To provide a mounting surface for the throat damper assembly
- To catch falling debris and prevent downdrafts from pushing smoke into the room (Correct answer)
- To increase the velocity of smoke entering the flue
- To separate the primary combustion air from the secondary air supply
Correct answer: To catch falling debris and prevent downdrafts from pushing smoke into the room
The smoke shelf is a horizontal ledge located behind the damper that catches debris falling from the flue and disrupts downdrafts, preventing smoke from entering the living space.
Question 4: What does a deteriorating or missing chimney crown typically cause?
- Increased draft velocity leading to over-firing
- Water intrusion into the chimney structure and surrounding masonry (Correct answer)
- Backdrafting due to negative pressure at the flue opening
- Creosote buildup on the interior flue tiles
Correct answer: Water intrusion into the chimney structure and surrounding masonry
The chimney crown seals the top of the masonry chimney around the flue tile; when it cracks or deteriorates, water enters the chimney structure causing accelerated damage.
Question 5: Per InterNACHI inspection standards, what minimum clearance to combustible materials is required for a factory-built (zero-clearance) fireplace?
- Must follow the clearances listed by the manufacturer's installation instructions (Correct answer)
- Minimum 2 inches to all combustible framing members
- Same as masonry fireplaces — 2 inches to all sides
- No clearance required because the firebox is pre-insulated
Correct answer: Must follow the clearances listed by the manufacturer's installation instructions
Factory-built fireplaces are listed appliances, and inspectors must verify that clearances match the manufacturer's installation instructions, as these vary by model.
Question 6: When inspecting the flashing at a chimney base, which condition represents a deficiency requiring reporting?
- Step flashing that overlaps the counter-flashing by 2 inches
- Caulk-only installation with no metal counter-flashing embedded in mortar (Correct answer)
- Aluminum step flashing installed on an asphalt shingle roof
- Base flashing extending 4 inches up the chimney face
Correct answer: Caulk-only installation with no metal counter-flashing embedded in mortar
Relying on caulk alone without embedded counter-flashing is a maintenance workaround that fails over time; proper installation requires metal counter-flashing set into the chimney mortar joints.
Question 7: Third-degree creosote in a chimney flue is classified as:
- Light sooty deposits that can be brushed away easily
- Flaky or crunchy tar deposits removable with standard brushes
- Hardened, glazed tar that is highly concentrated and difficult to remove (Correct answer)
- A gas-phase byproduct requiring ventilation only
Correct answer: Hardened, glazed tar that is highly concentrated and difficult to remove
Third-degree creosote is a concentrated, glazed, and extremely flammable deposit that bonds tightly to the flue liner and requires professional chemical treatment or liner replacement.
InterNACHI Fireplaces, Chimneys & Solid Fuel Appliances 2
Spalling observed on a masonry chimney exterior refers to: