Don’t let rust destroy your corrugated roof.
By understanding why fasteners fail, you can prevent unnecessary corrosion and ultimately extend the life of your roofing.
At Cardinal Steels, we provide a wide range of roofing fixings to give your project a secure but professional finish.
This article will explore the common reasons why fasteners fail and the preventative methods you can take to halt it.
What Are Corrugated Roofs and Their Fasteners?
Corrugated roofing sheets have a wavy or ridged pattern, giving them extra strength and rigidity.
Each sheet provides consistent coverage, making them suitable for a wide range of buildings, including agricultural sheds and workshops.
At Cardinal Steels, our corrugated sheets are manufactured in a 13.5/3 profile and come in a choice of three coatings (galvanised, polyester and plastisol).
We supply matching fasteners such as Tek screws and screw caps, all colour-matched to the roofing.
These fasteners:
- Secure the sheets to the structure.
- Prevent movement and wind uplift.
- Seal fixing holes to keep out water.
What Causes Roof Fasteners to Rust?
Even high-quality screws can corrode if installed or maintained incorrectly. Here are the main causes:
1. Water Leaks and Trapped Moisture
When the rubber washer under a screw head fails, moisture can enter and sit around the fixing point.
A washer may fail if it is:
- Damaged
- Under tightened
- Over tightened
- Aged
It stops sealing properly, causing rainwater to seep in and get trapped around the hole.
Continuous dampness results in oxidation to the metal, ultimately causing it to rust.
This can have a detrimental impact on the security of the corrugated roof as screws can snap, loosen or break causing panels to loosen or lift.
2. Ageing or UV Damage to Rubber Washers
Rubber washers which sit between the metal screw head and roofing sheet are intended to create a waterproof seal.
Sun exposure and temperature changes can cause rubber washers to harden, crack or shrink.
This can cause the seal to fail, allowing water to seep in which will eventually create corrosion.
3. Damage to Screw Coatings
Metal screws often have a protective coating to prevent corrosion.
If this coating is scratched during installation or worn by tools, the exposed steel reacts with oxygen and moisture.
This accelerates rust formation and reduces the fastener’s strength.
How to Prevent Rust on Corrugated Roof Fasteners
Preventing rust starts with good installation, regular inspection and quality materials.
1. Tighten Screws Correctly
Refrain from overtightening or under-tightening screws to prevent crushing or not compressing the rubber washer so that the waterproof seal works effectively.
Too tight, and the washer crushes; too loose, and it won’t seal properly. A balanced torque ensures a watertight seal and protects the washer’s shape.
2. Inspect and Replace Fasteners Regularly
Regularly inspect and replace fasteners when deemed necessary. This ensures you can rectify small problems before they turn into expensive ones.
Replace rusty or damaged screws promptly to stop small issues from becoming expensive repairs.
3. Use Stainless Steel Fasteners with Neoprene Washers
Use stainless steel screws with UV- UV-resistant neoprene washers.
Stainless steel has an invisible oxide layer to protect the metal from corrosion, whilst neoprene is a synthetic rubber that resists sunlight damage.
These two fasteners combined will help prevent corrosion, rust and staining.
Conclusion
Rusting under fasteners is a common problem, but through regular inspections, the right installation and conscious choices, the rust can be kept at bay.
Moisture, UV exposure and damaged coatings are the main causes, but correct tightening, regular maintenance and quality materials, such as stainless steel screws with neoprene washers, provide long-term protection.
At Cardinal Steels, we sell a range of ancillary products for your steel roof fixings to keep your roof secure and watertight for years to come.
