CCS CCS Chimney Cap & Crown Systems 2 — Questions and Answers
Question 1: What is a chimney crown and where is it located?
- A decorative band around the chimney exterior
- The concrete or mortar slab that covers the top of the masonry chimney, surrounding the flue (Correct answer)
- Another name for the chimney cap
- The metal flashing at the roofline
Correct answer: The concrete or mortar slab that covers the top of the masonry chimney, surrounding the flue
The chimney crown is the concrete or mortar slab built over the top of the masonry chimney to shed water away from the flue, separate from the cap itself.
Question 2: What is the recommended overhang for a properly built chimney crown beyond the face of the chimney?
- Flush with the chimney face
- At least 2 inches (Correct answer)
- Exactly 1 inch
- 4 to 6 inches
Correct answer: At least 2 inches
A chimney crown should extend at least 2 inches beyond the chimney face to direct water away from the masonry and prevent moisture infiltration.
Question 3: Which crown defect is most commonly found during a chimney inspection?
- Incorrect color matching
- Cracks or spalling in the crown surface (Correct answer)
- Crown installed too high above the roofline
- Crown made of stainless steel rather than concrete
Correct answer: Cracks or spalling in the crown surface
Cracking and spalling are the most common crown defects, caused by freeze-thaw cycles that allow water to penetrate and break apart the crown material.
Question 4: What product is commonly used to seal hairline cracks in a chimney crown without full replacement?
- Portland cement mortar
- Elastomeric crown sealer or sealant (Correct answer)
- Roofing tar
- Hydraulic cement
Correct answer: Elastomeric crown sealer or sealant
Elastomeric crown sealers are flexible coatings that bridge hairline cracks and resist further freeze-thaw movement without the need to rebuild the crown.
Question 5: A chimney crown should be constructed with which type of mix to ensure long-term durability?
- Pure lime putty
- Portland cement-based mix (not mortar mix) (Correct answer)
- Standard brick mortar
- Premixed drywall compound
Correct answer: Portland cement-based mix (not mortar mix)
Portland cement-based concrete is required for crowns because standard mortar mix lacks the strength and water resistance needed to withstand outdoor exposure.
Question 6: Why must a gap be left between the flue liner and the chimney crown?
- To allow the crown to be removed for inspection
- To accommodate thermal expansion of the flue liner without cracking the crown (Correct answer)
- To improve the decorative appearance
- To allow rain to drain between the liner and crown
Correct answer: To accommodate thermal expansion of the flue liner without cracking the crown
Leaving a gap (often filled with a flexible caulk) between the flue liner and crown prevents the thermally expanding liner from cracking the crown.
CCS CCS Chimney Cap & Crown Systems 2
What is a chimney crown and where is it located?