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Gutter size and downspouts
Pick 5 in or 6 in gutters and count downspouts.
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How this works
Adjusted area = roof plane area × pitch factor × local maximum rainfall intensity (in/hr). Typical capacity: 5 in K-style ≈ 5,520 sq ft, 6 in K-style ≈ 7,960 sq ft of adjusted area. Plan one downspout per 30 to 40 ft of gutter.
Related guide
Gutters & drainage guide
Plan a gutter and downspout system that handles roof runoff, directs water away from the foundation, and fits your maintenance needs.