Common Chimney Defects

Inadequate Wall Thickness

• Minimum thickness of unlined chimney is 8 inches
• Minimum thickness of lined chimneys is 4 inches
• Poor liner or firebox joints
• Separation of fireplace face and firebox

Should be at least 3 feet higher than roof structure; top at least 2 foot taller than any other component or structure within 10 feet. Known as "3-2-10 Rule"

• Flue area should never be less than 1/12 of fireplace opening
• Damper installed too low
• Damper missing
• Fireplace too large for flue
• Inadequate draft
• Lack of combustion air