NHIE Fireplaces, Chimneys and Solid-Fuel Burning Appliances — Questions and Answers
Question 1: Under the common 3-2-10 rule, how high must a masonry chimney extend?
- At least 3 feet above the roof penetration and 2 feet higher than any part of the building within 10 feet (Correct answer)
- At least 2 feet above the roof penetration and 3 feet higher than any part of the building within 10 feet
- At least 10 feet above the roof penetration regardless of nearby structures
- At least 3 feet above the ridge, no matter where the chimney sits on the roof
Correct answer: At least 3 feet above the roof penetration and 2 feet higher than any part of the building within 10 feet
The IRC 3-2-10 rule says a chimney must extend at least 3 feet above the point where it passes through the roof. It must also be at least 2 feet higher than any part of the building within 10 feet horizontally. This gives proper draft and keeps sparks away from the roof.
Question 2: A masonry fireplace has an opening of less than 6 square feet. What is the minimum hearth extension in front of the opening?
- 8 inches
- 12 inches
- 16 inches (Correct answer)
- 20 inches
Correct answer: 16 inches
For openings under 6 square feet, the hearth extension must reach at least 16 inches in front of the opening and 8 inches past each side. For openings of 6 square feet or more, it must reach 20 inches in front and 12 inches past each side.
Question 3: What is the minimum air-space clearance between combustible framing and a masonry chimney located entirely inside the house?
- 0 inches; framing may touch the masonry
- 1 inch
- 2 inches (Correct answer)
- 6 inches
Correct answer: 2 inches
The IRC requires 2 inches of clearance between combustibles and masonry chimneys located inside the building. Chimneys on the exterior of the building need only 1 inch. Framing that touches the masonry is a fire hazard and should be reported.
Question 4: When is a cricket (saddle) required on the uphill side of a chimney?
- Whenever the roof is covered with asphalt shingles
- When the chimney is wider than 30 inches measured perpendicular to the roof slope (Correct answer)
- Only when the roof pitch is less than 4:12
- Only on chimneys that serve wood-burning appliances
Correct answer: When the chimney is wider than 30 inches measured perpendicular to the roof slope
The IRC requires a cricket when the chimney is more than 30 inches wide parallel to the ridge, that is, across the slope. The cricket sends water around the chimney so it doesn't pond behind it and leak through the flashing.
Question 5: During an inspection you see the brick faces flaking and breaking off near the top of a masonry chimney. What is the most likely cause?
- Too much draft in the flue
- Water getting into the masonry followed by freeze-thaw cycles (spalling) (Correct answer)
- Burning hardwood instead of softwood
- A damper that is too small for the fireplace opening
Correct answer: Water getting into the masonry followed by freeze-thaw cycles (spalling)
Spalling happens when water soaks into brick or mortar, freezes, and expands, breaking off the surface. A missing or damaged chimney cap or crown, or poor flashing, is often the source of the water. It should be reported and repair recommended.
Question 6: A home inspector sees a thick, glossy black buildup inside the visible part of a wood-burning fireplace flue. What is the most appropriate action?
- Ignore it, because flue interiors are always outside the inspection scope
- Scrape a sample to confirm what it is before writing the report
- Report it as a possible creosote fire hazard and recommend cleaning and evaluation by a qualified chimney professional (Correct answer)
- Tell the client the fireplace is safe if the damper opens and closes
Correct answer: Report it as a possible creosote fire hazard and recommend cleaning and evaluation by a qualified chimney professional
Glazed creosote is a highly flammable byproduct of incomplete combustion and a major cause of chimney fires. Inspectors report what they observe and refer the client to a specialist, such as a chimney sweep doing a Level II inspection. Testing materials destructively is outside the inspector's role.
