3-2-10 Rule for Chimney Height

This is a pretty basic rule for chimney construction. A chimney must project at least 3 feet above the roof on its shortest side and also be at least 2 feet above any roof structure that is within a 10 foot radius of the chimney. That’s it.

Following this simple rule helps to ensure other structures on the roof do not interfere with the exhaustion of combustion gases. Having said that, following this rule does not guarantee adequate drafting will occur – there are a few other factors at play. The 3-2-10 rule is a good basic rule to follow to create a situation where good drafting is likely.