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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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