Chimney Height Calculator
Calculate the required chimney height based on building codes.
Includes the 3-2-10 rule and draft requirements.
Required Chimney Height
The 3-2-10 rule is the standard building code for chimney height:
- The chimney must extend at least 3 feet (0.9 m) above the point where it passes through the roof
- The chimney top must be at least 2 feet (0.6 m) higher than any part of the roof within 10 feet (3 m) horizontally
Why chimney height matters:
- Too short = poor draft, smoke enters the house
- Too tall = excessive draft, wastes fuel
- Code compliance is required for safety and insurance
Draft calculation: Taller chimneys create stronger natural draft because hot flue gases rise.
Draft (inches water column) ≈ Height (ft) × 0.007 × (1 - (Outside Temp / Flue Temp))
Recommended minimum flue gas velocity: 15 ft/s (4.6 m/s) for proper draft.
Additional clearance rules:
- 2 feet above any structure within 10 feet (adjacent buildings too)
- Local codes may require more height in some regions