By Hu Xianzhe, Cold Roll Forming Technical Engineer at ZTRFM | Last Updated: September 15, 2026
A distributor from Kenya sent me three photos last month. He wanted to buy "a roofing sheet machine." The first photo showed a warehouse roof with wide corrugated sheets. The second showed a factory wall with trapezoidal panels. The third showed a residential project with what looked like IBR sheets. I had to tell him: those are three different profiles, and you need to decide which one you're making before I can quote you a machine.
The Three Main Roofing Profiles
1. Corrugated (Round Wave)
The classic wavy sheet. You've seen it on sheds, agricultural buildings, and cheap roofing everywhere. The wave shape is sinusoidal -- smooth curves, no sharp angles.
Common specs: Wave height 15-25mm, pitch 76-125mm (the 76mm pitch is the most common in Africa and South Asia). Typical sheet width after forming: 1000mm (from 1219mm or 1250mm coil).
Best for: Agricultural buildings, warehouses, fences, low-cost housing. The round wave sheds water well and is forgiving if the installation isn't perfect.
Weakness: Low load-bearing capacity compared to trapezoidal. Not ideal for large-span roofs without purlins close together.
2. Trapezoidal (Box Rib)
Flat sections separated by raised ribs with sloped sides. Think of it as a more structural version of corrugated. The flat areas are wider, and the ribs are taller and more angular.
Common specs: Rib height 20-35mm, pitch 200-300mm. Popular variants include 840 (8 waves, 840mm coverage), 900, and 750 profiles. These numbers refer to the effective coverage width in millimeters.
Best for: Industrial roofs, commercial buildings, wall cladding. Higher load capacity than corrugated. The flat sections also look cleaner, which matters for visible applications.
Weakness: More expensive to tool than corrugated. The sharper bends require more forming stands.
3. IBR (Inverted Box Rib)
IBR is a specific trapezoidal profile that originated in South Africa and is now common across Africa and Australia. It has broad flat bottoms with relatively narrow, deep ribs. The "686" IBR profile (686mm coverage width) is the standard.
Common specs: Rib height 30-32mm, 6 ribs, effective width 686mm (from 1000mm coil). The deep ribs give it excellent stiffness for its weight.
Best for: African and Australian markets. If you're selling to these regions, IBR is often the expected profile. It handles wind loads well and looks professional.
Weakness: Regional. Buyers in South America or Southeast Asia may not recognize IBR and prefer their local trapezoidal profiles.
Machine Differences: What Actually Changes
The basic machine structure is the same for all three profiles -- uncoiler, feeding guide, forming stands, straightening, cut-off, run-out table. What changes is the tooling (rollers) and sometimes the number of stands.
| Aspect | Corrugated | Trapezoidal | IBR |
|---|---|---|---|
| Forming stand count | 10-12 | 14-18 | 16-20 |
| Thickness range | 0.2-0.8mm | 0.3-1.0mm | 0.3-0.8mm |
| Roller complexity | Simple (curves only) | Moderate (flat + angles) | Moderate (flat + ribs) |
| Typical line speed | 15-25 m/min | 12-20 m/min | 12-18 m/min |
| Machine price range | $8,000-15,000 | $12,000-25,000 | $14,000-28,000 |
The price differences come from two things: number of stands (more stands = more rollers = more cost) and roller machining complexity. Trapezoidal and IBR rollers have flat surfaces that need precise grinding to avoid marking PPGI material.
Can One Machine Make Multiple Profiles?
Yes, but with caveats. A "double-layer" or "duplex" machine has two sets of rollers stacked on the same frame. You feed material through the top layer for one profile, or the bottom layer for another.
I've installed several of these. They work, but here's the trade-off:
- Pros: Save floor space, lower total cost than two separate machines, quick profile switch (10-20 minutes).
- Cons: The frame is heavier and more complex, maintenance is harder (access to the bottom layer is tight), and the machine is taller. If one layer breaks down, the whole machine stops.
My recommendation: if your production volume is under 500 tons/month and you need two profiles, a duplex machine makes sense. Above that, get two dedicated machines. Downtime on a duplex machine during peak season costs more than the second machine.
PPGI vs Bare Galvanized: Does It Affect Machine Choice?
Yes. If you're running pre-painted steel (PPGI), you need rollers with a smoother surface finish. Chrome-plated or polished Cr12MoV rollers prevent paint scratching. For bare galvanized steel, standard nitrided rollers are fine.
If you plan to run both, specify the machine for PPGI. A PPGI-capable machine can run bare galvanized without issues, but the reverse isn't always true.
Quick Q&A
What's the minimum order quantity for roofing sheet machines? One machine. This is standard equipment, not custom. Most manufacturers have it in stock or can build it in 15-20 days.
Can I change the profile later? You can swap roller sets, but it requires removing and reinstalling all stands. Cost of a second roller set is typically 30-40% of the machine price. Not something you want to do often.
What coil width do I need? For corrugated: 1000mm or 1219mm. For trapezoidal 840: 1000mm. For IBR 686: 1000mm. Always confirm with the machine supplier before ordering coil -- the forming width is specific to the tooling design.
Do I need a flying saw? For continuous production (cutting without stopping the line), yes. For batch production where you stop to cut, a stationary saw is fine and costs less. Most entry-level machines use stationary cutting.
Frequently Asked Questions (FAQ)
What is the minimum order quantity for a roofing sheet machine?
The minimum order is one machine. The article describes it as standard equipment that manufacturers may stock or build in about 15-20 days.
Can the roofing profile be changed later?
A roller set can be swapped, but all stands must be removed and reinstalled. A second roller set typically costs 30-40% of the machine price, so this is not intended as a frequent change.
What coil width is needed for common roofing profiles?
The article states 1000 mm or 1219 mm for corrugated, 1000 mm for trapezoidal 840, and 1000 mm for IBR 686, while advising confirmation with the machine supplier because tooling determines forming width.
Is a flying saw required?
A flying saw is needed for continuous cutting without stopping the line. A lower-cost stationary saw is suitable for batch production where the line stops to cut.
