How to Create a Basic Profile Sketch (Roll Forming Guide)

Learn how to create a basic metal roofing profile sketch with correct dimensions, rib height, angles and effective cover for quoting.

Step-by-Step Guide for Roofing & Roll Forming Profiles

You do not need CAD software to create a usable profile sketch.

You need:

✔ Clear geometry
✔ Correct dimensions
✔ Consistent units
✔ Logical structure

A simple, clean sketch is enough for:

✔ Accurate quoting
✔ Developed width calculation
✔ Machine design
✔ Tooling layout

Most quoting delays happen because:

Sketches are incomplete or unclear.

This guide shows how to avoid that.

1️⃣ Start With Effective Cover Width

The first dimension you must define:

Effective cover width.

This is the visible installed width after overlap.

Example:

1000 mm effective cover
914 mm (36") effective cover

Write this clearly at the top of your sketch.

This is the most commercially important dimension.

2️⃣ Draw the Cross Section (Not the Length)

Roll forming profiles are defined by:

Cross-sectional geometry.

Draw a side view slice of the profile.

Do NOT draw:

Panel length.

Only draw the cross section shape.

3️⃣ Define Rib Height

Measure from:

Lowest valley
To highest peak.

Example:

35 mm rib height
32 mm rib height
45 mm rib height

Rib height affects:

✔ Structural strength
✔ Drainage
✔ Wind resistance
✔ Machine design

Write it clearly.

4️⃣ Define Rib Pitch

Rib pitch is:

Distance between rib centers.

Example:

200 mm pitch
250 mm pitch

Even if approximate, it helps manufacturers understand spacing.

5️⃣ Define Flat Pan Width

Flat areas between ribs must be dimensioned.

These affect:

✔ Oil canning risk
✔ Solar compatibility
✔ Structural stiffness

Indicate:

Pan width clearly between bends.

6️⃣ Show All Bend Angles

Each bend must have:

Angle defined.

Example:

90°
45°
60°

Sharp bends increase tooling complexity.

Even approximate angles help significantly.

7️⃣ Include Return Lips (If Any)

Many trapezoidal profiles include:

Return legs at the top.

Example:

10 mm inward return
15 mm stiffening lip

These are critical.

Missing lip information can change machine cost.

8️⃣ Indicate Overall Width (Optional but Helpful)

Overall width includes:

Overlap area.

Effective width excludes it.

If possible, include both.

9️⃣ Specify Thickness

Write clearly:

0.4 mm
0.5 mm
0.6 mm
Range: 0.4–0.6 mm

Without thickness:

Sketch is incomplete.

Thickness affects:

Developed width
Forming pressure
Machine power

🔟 Specify Steel Grade

Example:

G350
S350GD
G550

Higher grade increases forming complexity.

Write this under thickness.

1️⃣1️⃣ Indicate Coating

Example:

Z275
AZ150
Prepainted

This helps determine roller surface requirements.

1️⃣2️⃣ Keep Units Consistent

Do not mix:

Inches and millimeters.

Choose one system.

Metric preferred for international work.

If using inches, label clearly.

1️⃣3️⃣ Simple Trapezoidal Sketch Example (Text Layout)

Effective Cover: 1000 mm
Rib Height: 35 mm
Pitch: 250 mm
Thickness: 0.5 mm
Grade: S350
Coating: Z275

Then draw trapezoidal shape with labeled dimensions.

That is enough to begin engineering work.

1️⃣4️⃣ Common Sketch Mistakes

❌ No effective width
❌ No rib height
❌ No thickness
❌ No steel grade
❌ Using only photo reference
❌ Drawing without dimensions

A profile without dimensions cannot be priced.

1️⃣5️⃣ When to Use CAD

Hand sketch is acceptable for early quoting.

CAD is required for:

✔ Final tooling design
✔ Production approval
✔ Structural calculation

Start simple. Refine later.

1️⃣6️⃣ How Manufacturers Use Your Sketch

They will:

1. Calculate developed width

2. Determine forming sequence

3. Estimate station count

4. Calculate motor power

5. Design tooling

6. Generate quotation

The clearer your sketch, the more accurate the quote.

1️⃣7️⃣ If You Don’t Know Exact Dimensions

You can:

✔ Measure existing installed panel
✔ Use calipers
✔ Measure center-to-center rib spacing
✔ Measure height with ruler

Even approximate numbers are better than none.

1️⃣8️⃣ Engineering Summary

A usable profile sketch must include:

✔ Effective cover width
✔ Rib height
✔ Rib pitch
✔ All bend dimensions
✔ Thickness
✔ Steel grade
✔ Coating

Without these:

Manufacturer is guessing.

With them:

Manufacturer is engineering.

FAQ Section

Can I send a hand-drawn sketch?

Yes, if dimensions are clear.

Is a photo enough?

No — photos do not show exact measurements.

Do I need CAD?

Not initially, but for final approval yes.

What is the most important dimension?

Effective cover width.

Should I include overlap detail?

Yes, especially for roofing profiles.

Can manufacturer design the profile for me?

Yes, but you must define target application and width.