Impact of metal roof screws rusting & how to prevent the damage

Rust, the most feared phenomenon and common enemy among builders and owners alike of any building structure, especially ones that are exposed to the elements.  For coastal areas, salt haze formed by evaporation of sea spray corrodes and weakens the structure and also roofing screws.  In other areas, corrosion may result from acids spread from industry, vapors from agricultural fertilizers or pesticides, fumes from petrochemical sites, UV ray exposure, and humidity. Metal roof screws rusting will have negative impact on buildings regardless of its root cause of failure.


Impact of metal roof screws rusting & how to prevent further damage

The cause and effect of metal roof screws rusting.

When it comes to metal roofing and wall cladding, manufacturers have put in lots of effort in the development of coatings and layering technologies to enhance weathering resistance; some even have up to five layers of coatings, each with its own unique properties to cope with severe environment, and warranted up to 50 years.


A very important aspect that the majority fail to realize is, these roofing sheets will live up to its projected life expectancy only if the screws and accessories used alongside them performs equally well. The overall lifespan of the metal roof covered area depends on whether there are metal roof screws rusting or not. One of the main reasons oftentimes we see really high-tech metal roofing sheets that are fixed with screws that offer little to no weathering resistance at all, which totally negates the purpose of using these high corrosion-resistant sheets in the first place.  A responsible roofing sheet salesperson should specify the type of screw with matching weathering resistance when making sales.


The majority of metal roofs are fixed with exposed fasteners, as opposed to concealed fixings roof where the fasteners are covered against the elements; being exposed means that fixings are the first thing that comes into sight when looking over rooftop, and any sign of rust awfully visible, though it is generally overlooked and often not dealt with until it’s too late and damage has spread to the roof sheet or even inside the building.


How to prevent building damage caused by metal roof screws rusting?

We suggest biennial inspections in coastal, high humidity, or highly polluted industrial areas, and quinquennial inspections in rural, less polluted areas.  Have an experienced builder or technician examine the site in question alongside you, as they should provide expert opinion on whether the rust is an immediate threat that requires replacement of the fasteners asap, or could be held off until the next season or renovation.


Since having metal roof screws rusting or not is detrimental to the safety and life expectancy of the building, if upon inspection, the roofing screws are really rusty, and the threat of damage imminent requiring immediate action; the following steps will guide you to choosing the correct corrosion resistant screw category for the job.

  • Understand your environment. For example, areas close to the coast will be at high risk to corrosion due to high salt content in the atmosphere compared to the inland, and therefore would require high weathering resistant fasteners on structures.
  • There are multiple choices on the market when it comes to corrosion resistant coatings, and products are normally priced according its service life and warranty terms and conditions.
  • Since it is impossible to tell from the naked eye how effective the coatings really are, a reputable company will provide accredited 3rd party test lab reports as proof of compliance.



For more information on metal roof screws rusting, corrosion resistance and service life in relation to the environment the fasteners are used in, kindly contact your local BDN Fasteners distributor or salesperson, or simply click on Choosing the correct screws for metal roofing sheets installation to understand the scope of warranty for our products and the environment category classification they are base upon. Choose the correct screws to prevent the building impact from metal roof screws rusting.


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