What chimney height rule means
The chimney height rule sets how far a chimney must rise above the roof and above anything nearby, so it drafts and its sparks clear the roof.
Also called three-two-ten rule.
Where it matters on a chimney job
Short chimneys draft poorly and smoke back into the room. When a homeowner complains about smoke, check the height before anything else. Adding height is masonry or a listed extension, and either is a quote of its own.
What the model code says
- A chimney must be at least 2 feet higher than any part of the building within 10 feet, and at least 3 feet above where it passes through the roof. (IRC 2021, Chapter 10)
Check which code edition your building department enforces for chimney height rule before you quote.
What it costs
The chimney repair cost guide has the typical job at $600 and the usual range at $210 to $980. The guide shows its sources and what moves the price.
Work it out
- Cost guide: Chimney repair cost
- Tools, templates and guides: Free chimney resources
Sources: 2021 International Residential Code, Chapter 10, Chimneys and Fireplaces (ICC). Checked October 9, 2026.