IBR is pierce-fixed through the crown. Klip-Lok clips onto concealed brackets with no penetrations at all. On an exposed Southern Cape roof that difference decides more than appearance does.
IBR vs Klip-Lok for Cape Coastal Wind — practical guidance from the team running IBR and Klip-Lok roofing on the Garden Route. Here is how the two profiles actually behave in wind and salt, where each one belongs, and the specification details that matter more than the profile choice itself.
The fundamental difference: pierced versus concealed
IBR — inverted box rib — is a trapezoidal profile fixed with screws driven through the crown of the rib into the purlin below. Every fixing is a hole through the sheet, sealed by a washer under the screw head.
Klip-Lok is a concealed-fix profile. Clips are fastened to the purlins first, and the sheet snaps down over them. The fasteners never pass through the weathering surface, so there are no holes in the roof plane at all.
That single difference drives nearly everything else. Pierced fixings are the most common leak path on a steel roof and the first thing to fail in salt air, because the washer perishes and water tracks down the screw shank. A concealed-fix roof simply does not have that failure mode.
The trade-off is that Klip-Lok relies entirely on the clips and the sheet geometry to hold down. Get the clip spacing or the purlin centres wrong and the roof has no secondary defence, where an IBR roof at least has screws through it.
How each behaves in wind
Wind uplift on a roof is not uniform. Pressures are highest at the eaves, the ridge and especially the corners, which is why fixing patterns are supposed to be denser in those zones.
IBR resists uplift through the fasteners. More screws means more resistance, and in exposed positions the specification calls for fixing at closer centres rather than the standard pattern. The weak point is that each fastener concentrates load at a single hole in the sheet, and repeated flexing in gusty conditions elongates that hole over time.
Klip-Lok spreads the load across the clips and allows the sheet to move thermally without working the fixings, which is a genuine advantage on long runs. But it has a lower tolerance for being wrong: the sheet can unzip from the clips under sustained uplift if the clip spacing was not designed for the exposure.
For a genuinely exposed Southern Cape roof — a ridge line, a coastal plot with no shelter, a long unbroken plane — both work, but both need the fixing or clip pattern designed for the position rather than taken off a standard table.
Salt, coatings and cut edges
Within a few kilometres of the sea, the coating specification matters more than the profile. Both IBR and Klip-Lok are rolled from the same coated coil, so this is a separate decision from the profile choice.
The base metal matters first. AZ150 aluminium-zinc coated steel substantially outperforms standard galvanised in marine conditions. Then the paint system on top of it — a good coated finish such as Chromadek in the appropriate grade, rather than a bare or lightly coated sheet.
Cut edges are where coated steel starts corroding, because the cut exposes the substrate. That means every sheet end, every penetration and every site-cut is a small vulnerability. It is one of the arguments for ordering sheets to length rather than cutting on site, and for treating unavoidable cuts.
Fasteners need to match. Putting a mild steel or lower-grade screw into a well-specified coated sheet in coastal air gives you a roof held on by the weakest component. Class 4 fasteners are the baseline near the sea.
Pitch, sheet length and where each profile stops working
IBR is generally suited to pitches from around 5 degrees upwards with appropriate lap treatment, and lower pitches need longer end laps and sealing. Klip-Lok, being concealed-fix and continuous, handles lower pitches more comfortably — down to around 2 to 3 degrees depending on the specific profile and manufacturer guidance.
Sheet length is the other practical factor. Long single-length sheets remove end laps altogether, which removes the most common leak path after fixings. Both profiles can be rolled long; Klip-Lok benefits more because it also removes thermal working at the fixings.
Where a roof has many penetrations, valleys or changes of plane, IBR is often the more practical choice simply because detailing around interruptions is more straightforward. A clean, long, simple plane is where Klip-Lok is at its best.
Cost, and what you are actually paying for
Klip-Lok costs more per square metre than IBR — the profile itself, the clips, and generally a heavier gauge. On a straightforward roof, IBR is the cheaper installed cost and will be for the foreseeable future.
What the extra buys is the absence of penetrations, better thermal behaviour on long runs, and a cleaner appearance without visible fixings. On an exposed coastal roof where fixings are the known failure point, that is a real durability argument rather than an aesthetic one.
The honest position: on a sheltered inland roof with normal spans, well-specified IBR at the correct fixing centres is entirely adequate and better value. On an exposed coastal plane, particularly a long low-pitch one, Klip-Lok earns its premium.
What we specify and why
We look at exposure first — how sheltered the site is, the prevailing wind, distance from the sea. Then the roof geometry: pitch, span, number of penetrations, whether single-length sheets are possible.
Coating comes next, and near the water that means AZ150 substrate with an appropriate coated finish, matched fasteners, and treated cut edges. That decision usually matters more to the life of the roof than the profile.
Then the fixing or clip pattern, densified at eaves, ridge and corners rather than uniform across the plane. This is the detail that is most often taken off a generic table and is most often the reason a roof lifts.
We would rather put a well-specified IBR roof on with the correct fixings and coating than an under-specified Klip-Lok roof that looks better and is held on by clips at the wrong centres.
Frequently asked questions
Which is better, IBR or Klip-Lok?
Neither is universally better. Klip-Lok is concealed-fix with no penetrations through the sheet, which removes the most common leak and corrosion path and suits exposed, low-pitch and long-run roofs. IBR is pierce-fixed, cheaper, and easier to detail around penetrations and complex geometry. Exposure and roof shape should decide it.
Is Klip-Lok better in wind?
It spreads uplift across clips and lets the sheet move thermally without working the fixings, which helps on long exposed runs. But it depends entirely on clip spacing being designed for the exposure — there is no secondary fixing if it is wrong. Correctly specified, both profiles perform; incorrectly specified, Klip-Lok has less margin.
What is the difference between IBR and Klip-Lok?
IBR is fixed with screws through the crown of the rib, so every fastener is a hole through the sheet. Klip-Lok clips onto concealed brackets fixed to the purlins, so no fastener penetrates the weathering surface. That is the fundamental difference and it drives the leak behaviour, the corrosion behaviour and the appearance.
What is the minimum pitch for IBR roof sheeting?
Around 5 degrees for standard detailing, with longer end laps and sealing required as the pitch reduces. Concealed-fix profiles such as Klip-Lok go lower, typically to around 2 to 3 degrees depending on the specific profile. Always check the manufacturer’s figure for the exact profile rather than relying on a general rule.
What roof sheeting is best for coastal areas?
The coating matters more than the profile. AZ150 aluminium-zinc substrate with a quality coated finish substantially outperforms standard galvanised in salt air, matched with Class 4 fasteners. Treat or avoid site cuts where possible, because cut edges are where coated steel begins to corrode.
Why do the screws on my IBR roof leak?
The sealing washers under the fastener heads have perished from UV and thermal movement, and salt air has corroded the head. Water then tracks down the screw shank. It is the most common steel roof repair on this coast, and it is fixed by re-fixing with new fasteners and washers rather than replacing the roof.
Can you put Klip-Lok over an existing roof?
Sometimes, but it depends on the condition and spacing of the existing purlins, since the clips fix to them. Over-roofing can be a sound approach where the structure is good and the existing covering is sound but weathered. Where the purlins are corroded or spaced wrong for the new profile, it is not a shortcut worth taking.
Related reading
- Metal roofs: profile, gauge and coating
- Coastal corrosion on South African roofs
- Picking a roof for Cape coast wind
- IBR and Klip-Lok roofing in George
- All our roofing services
Specifying a steel roof on the coast?
We’ll look at the exposure, the geometry and the distance from the sea, and specify the profile, coating and fixing pattern to match — not off a standard table.
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