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Calculate Gutter Size for Your Roof

Size gutters and downspouts based on roof area and rainfall intensity. Prevent overflow and foundation damage.

📅 Updated April 2026 Formula verified 📖 4 min read 🆓 Free · No sign-up

Dimensionamento

Calha residencial 150 mm: suficiente para maioria. No Brasil, com chuvas tropicais intensas, o dimensionamento correto é crucial — uma calha subdimensionada transborda e causa infiltrações na fundação. Um tubo de descida a cada 10-12 m. Prolongadores devem afastar a água 1,5 m+ da fundação.

Manutenção

Limpe 2×/ano (outono e primavera). Calhas entupidas são a causa #1 de infiltrações na fachada. No Brasil, folhas de mangueiras, jabuticabeiras e outras árvores tropicais entopem rapidamente — protetores de calha (R$10-20/m) resolvem.

⚡ CalcWolf Insight

Foundation damage from poor drainage costs $5,000-30,000 to repair. Properly sized gutters and downspouts with extensions cost $1,500-3,000 installed. This is one of the highest-ROI home improvements — protecting your foundation protects your largest investment. Check your gutters during the next heavy rain and note any overflow points.

Frequently asked questions
Qual tamanho de calha?
150 mm para maioria residencial. Telhados grandes ou regiões de chuva intensa: 200 mm.
Frequência de limpeza?
2×/ano mínimo. Com árvores tropicais próximas: 3-4×.
✓ Math logic verified against primary sources → See our verification process
Kevin Glover
Founder, CalcWolf · GLVTS · Blickr
All formulas sourced from primary references — IRS publications, peer-reviewed research, and official standards. Results are tested against independent reference calculators before publishing. Rates and brackets updated when official sources change. Editorial policy →
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