⚡ Roof Flashing Calculator – Length & Cost Estimator
Calculate flashing length needed for valleys, chimneys, skylights, and roof edges — with cost per linear foot
Use this roof flashing calculator to measure total length requirements and estimate roof flashing cost per linear foot. Includes edges, walls, valleys, skylights, and dormers. Proper flashing ensures waterproofing and prevents costly leaks.
Result will appear here
💡 Tip: Flashing is inexpensive per linear foot, but poor installation can cost thousands in repairs.
📐 Flashing-specific cost and guidance will appear here after calculation.
✅ Best Practices:
• Use step flashing where roof meets vertical walls.
• Counterflashing required for chimneys.
• Continuous valley flashing improves water shedding.
• Overlap flashing pieces at least 2–4 inches.
• Nail only at top edge to allow water runoff.
• Use corrosion-resistant metals (galvanized, aluminum, or copper).
• Seal all joints with roofing cement.
• Check code for required flashing around penetrations.
• Skylights and dormers demand custom flashing kits.
• Replace damaged flashing immediately — leaks spread fast.
❓ FAQ - Roof Flashing Cost & Use
Q: What is roof flashing?
Thin metal pieces installed to prevent water intrusion at joints, valleys, and penetrations.
Q: How much does roof flashing cost per linear foot?
Basic galvanized flashing runs ~$1–$2 per linear foot, aluminum ~$2–$3, and copper can cost $5+ per foot. Use this calculator to estimate project totals.
Q: Which material is best?
Aluminum is cost-effective, galvanized steel is durable, copper lasts longest but is expensive.
Q: How much overlap is needed?
Typically 2–4 inches, but always check manufacturer instructions.
Q: Do chimneys need special flashing?
Yes — use step + counterflashing system for watertight seal.