What Coil Size Do I Need for Gravel Stop Flashing?

Gravel Stop Flashing Coil Size Guide (Before Forming)

Gravel stop flashing is used at the edges of flat and low-slope roofs to retain gravel or ballast while directing water off the roof. It provides a raised edge with a drip flange, preventing material wash-off and protecting roof edges.

The most important starting point in production is selecting the correct coil size before forming — especially the coil width, which defines the vertical face height, roof flange, and drip edge.

For gravel stop flashing, coil size directly affects:

• Gravel retention height
• Roof edge protection
• Water runoff performance
• Structural rigidity at roof edges
• Production efficiency

This guide explains exactly what coil size you need before forming gravel stop flashing.

What Is Included in “Coil Size”?

Coil size includes:

• Coil width (most critical)
• Thickness (gauge)
• Coil weight
• Coil inside diameter (ID)
• Coil outside diameter (OD)
• Material type and coating

All must match both flashing design and forming equipment.

1. Coil Width (Primary Factor)

The most important factor is the coil width before forming, based on the developed strip width.

For gravel stop flashing, this includes:

• Roof flange (horizontal section on roof)
• Vertical face (retaining gravel)
• Drip edge / kick-out (directs water away)
• Return hems (for stiffness and safety)
• Cleat or fixing sections (if used)
• Bend allowances

Typical coil width ranges:

• 200 mm – 350 mm → small residential flat roofs
• 350 mm – 600 mm → standard commercial roofs
• 600 mm – 900 mm+ → large industrial or high parapet edges

👉 Coil width must include roof flange + vertical face + drip edge

2. Thickness (Gauge)

Gravel stop flashing must be strong enough to resist wind uplift and material load.

Typical ranges:

• 0.5 mm – 0.7 mm → standard applications
• 0.7 mm – 1.0 mm → commercial roofs
• 1.0 mm – 1.5 mm+ → heavy-duty or high-wind environments

Thickness affects:

• Structural rigidity
• Resistance to deformation
• Wind uplift performance
• Durability

3. Coil Weight

Coil weight depends on production scale.

Typical coil weights:

• 1 – 3 tons → small to medium production
• 3 – 5 tons → standard roll forming
• 5 tons+ → high-volume production

4. Coil Inside Diameter (ID)

The coil ID must match the uncoiler.

Common sizes:

• 508 mm (20”) → standard
• 610 mm (24”) → larger systems

(Smaller IDs are less common due to heavier and wider material)

5. Coil Outside Diameter (OD)

OD depends on coil width, weight, and thickness.

Typical OD:

• 1000 mm – 1800 mm+

Must match:

• Uncoiler capacity
• Handling equipment
• Production layout

6. Material Type and Coating

Material selection is critical due to full exposure to weather and rooftop conditions.

Common materials:

• Pre-painted galvanized steel (PPGI)
• Galvanized steel (GI)
• Aluminum
• Stainless steel

Material affects:

• Corrosion resistance
• UV exposure resistance
• Structural performance
• Lifespan

Why Coil Size Is Critical for Gravel Stop Flashing

Gravel stop flashing plays both a structural and drainage role.

If coil size is incorrect:

• Gravel may spill over roof edges
• Water may not drain properly
• Drip edge may fail
• Roof edge protection will be compromised
• Installation issues will occur

Accuracy is critical for performance and durability.

Gravel Stop Geometry (Key Feature)

Gravel stop flashing typically includes:

• A horizontal roof flange
• A vertical face (retaining gravel)
• A drip edge or kick-out
• Optional hems and cleats

These require:

• Precise coil width
• Accurate bend locations
• Consistent forming

Incorrect coil size affects:

• Gravel retention
• Water runoff
• Structural integrity
• Visual finish

Common Coil Size Mistakes

• Incorrect width
  Insufficient height or poor roof coverage
• Ignoring drip edge allowance
  Water runoff issues
• Wrong thickness
  Weak profile OR difficult forming
• Incorrect material selection
  Reduced lifespan
• Poor slitting quality
  Visible edge defects

Machine Matching (Critical)

Before ordering coil, confirm your machine supports:

• Required coil width
• Thickness range
• Maximum coil weight
• Ability to form multiple bends and hems
• Material compatibility

👉 Coil size must match machine + flashing design

What Buyers Must Confirm Before Ordering Coil

Always confirm:

• Gravel stop design (height, flange size, drip edge)
• Roof system requirements
• Developed strip width
• Thickness
• Material type and finish
• Coil weight
• Coil ID / OD
• Machine limitations

Never estimate — always match flashing to roof design and environmental conditions.

Final Thoughts

For gravel stop flashing, the coil size before forming defines gravel retention, drainage, and roof edge protection.

Getting the coil size right ensures:

• Proper gravel containment
• Effective water runoff
• Strong and durable edge protection
• Clean and consistent profile
• Efficient production

Gravel stop flashing is critical for flat roof systems — coil size accuracy is essential.

FAQ

What coil size do I need for gravel stop flashing?
You need the correct coil width, thickness, weight, ID/OD, and material based on flashing design and roof requirements.

What is the most important factor?
Coil width — it determines height and roof flange coverage.

Why is the vertical face important?
It retains gravel and protects the roof edge.

Does thickness matter for gravel stop flashing?
Yes — it affects strength and wind resistance.

Can coil size be adjusted during production?
No — it must be correct before forming.