Gutter Calculator

Place one downspout every 20-30 linear feet of gutter, or one per 600 sq ft of roof area—whichever requires more. Position at corners and low points. Each downspout handles flow from about 600-800 sq ft of roof. In heavy rain areas, use more downspouts. Downspouts should be 2×3" for 5" gutters, 3×4" for 6" gutters.

Install hangers every 2-3 feet for proper support. For 100 ft of gutter, need 35-50 hangers. In snow areas, use 18-24" spacing. Hidden hangers inside the gutter look cleaner; external brackets are more traditional. Each hanger should support 25+ pounds. Use screws into fascia or rafter tails, not just into fascia board alone.

Gutter costs: USA $3-8/ft materials, $6-15/ft installed; Canada C$5-12/ft; UK £4-12/m; Australia A$15-35/m installed. Seamless gutters cost more but fewer leak points. Aluminum is standard; copper costs 3-5× more. Half-round is more expensive than K-style. DIY with sectional gutters saves 50% vs seamless professional install.

Gutters should slope 1/4" per 10 feet toward downspouts. For 40 ft run to a single downspout, the high end is 1" higher than the outlet. This ensures water flows and doesn't pool. Too much slope looks uneven from ground; too little causes standing water and debris buildup. Check level across gutter—warped gutters don't drain properly.

Seamless gutters are custom-made on-site with no seams except at corners—fewer leak points and cleaner appearance. Requires professional installation. Sectional gutters come in 10-20 ft pieces—DIY friendly but seams can leak over time. For DIY, sectional is practical. For longevity and appearance, seamless is superior. Both use same materials and hangers.

Gutter guards reduce cleaning but don't eliminate it. Mesh screens ($1-3/ft) block large debris but can clog with shingle grit. Foam inserts ($2-4/ft) fill the gutter. Solid covers with surface tension ($5-15/ft) work best for leaves. None are maintenance-free—all need occasional cleaning. Consider your tree situation before investing heavily.