Hexagonal roofs—used in gazebos, turrets, towers, and modern custom homes—are visually striking but notoriously tricky to flash correctly. With six (or more) intersecting planes and tight angles, flashing a hexagonal roof requires precision, planning, and experience.
Whether you’re a roofer taking on a specialty job or a homeowner trying to understand the complexity of your unique roof, this guide covers what you need to know about flashing installation for hexagonal roof structures.
🏠 Why Flashing Matters More on a Hex Roof
Flashing is the protective metal (or synthetic) barrier that seals roof joints against water intrusion. On hexagonal roofs, the stakes are higher because:
- The number of valleys and ridges is greater
- Water runoff converges more aggressively at angles
- Improper overlap or misaligned flashing can lead to fast-tracked leaks
Each segment of a hexagonal roof needs to be flashed with both water flow and directional runoff in mind.
📐 Key Flashing Points on Hexagonal Roofs
1. Valley Flashing
- With six intersecting roof panels, you’ll have six valleys, each forming a channel for water flow.
- Use open metal valley flashing, preferably W-style or double-W, to handle heavy runoff.
- Ensure underlayment overlaps flashing edges by at least 6 inches on both sides.
Tip: Install valley flashing first before any shingles or roof covering.
2. Hip and Ridge Flashing
- A hexagonal roof often includes six hip ridges that converge at a center peak.
- Flash each hip with pre-bent or custom-fabricated hip caps.
- If working with metal, consider ridge cap flashing with flexible foam closures to seal against wind-driven rain.
3. Center Cap or Finial Flashing
- Where all hips converge at the top, you’ll need either:
- A custom-fabricated metal finial or cap, OR
- A multilayered flashing assembly (e.g., lead or malleable copper) wrapped and sealed with roofing cement
- This point is vulnerable—make it watertight with double layers of flashing and underlayment beneath.
4. Step Flashing (if applicable)
If your hexagonal roof abuts a wall or chimney, step flashing is required along the vertical intersection.
- Each shingle course should have its own step flashing piece
- Use galvanized or copper step flashing cut to size (typical: 4″x6″ or 5″x7″)
- Seal with compatible caulk and counter-flashing when necessary
🔧 Installation Tips from the Field
✔️ Use Flexible Materials for Tight Angles
- Use lead, copper, or flexible aluminum flashing in areas with irregular angles
- Avoid rigid pre-bent flashing unless it’s custom-fabricated for your geometry
✔️ Pre-Bend Flashing Before Installation
- Measure exact valley angles—often 120° in regular hex roofs—and pre-bend metal in a brake
- Label each flashing piece to ensure proper placement and slope alignment
✔️ Overlap and Seal Properly
- Maintain at least a 6″ overlap at each intersection
- Use high-quality sealants (polyurethane or roofing-grade butyl) for joins and seams
- Always install from the bottom up to maintain water-shedding direction
✔️ Don’t Rely Solely on Caulk
- Flashing is a mechanical barrier, not just a sealed surface—use fasteners, proper layering, and gravity to your advantage
🔩 Materials to Consider
| Flashing Type | Best For | Notes |
|---|---|---|
| Aluminum | Lightweight, affordable | Easy to cut and bend; use with primer |
| Copper | High-end, historic or visible work | Expensive but long-lasting and malleable |
| Lead | Center caps, tight bends | Very pliable, good for tight top peaks |
| Galvanized Steel | Standard hip/valley flashing | Durable but harder to bend without tools |
🚫 Common Mistakes to Avoid
- Skipping ice and water shield under valleys
- Improper slope calculation, causing water to pool in valleys
- Failing to secure flashing properly on windy or exposed roofs
- Using roofing cement alone instead of properly layered flashing
Final Thoughts
Flashing a hexagonal roof is not a beginner task—it demands planning, precision cuts, and the right materials. But when done right, a properly flashed hexagonal roof is both durable and beautiful, capable of handling complex water flow and extreme weather conditions.
Whether you’re building a gazebo, turret, or modern hex-based home, don’t underestimate the importance of getting flashing details right—especially at valleys and ridges.