Replacing Roofing Screws
If you live near the coast, your roof will be affected by corrosion caused by the sea air. Fine particles of sea salt, usually formed by the evaporation of sea spray, creates a salt haze – and it is this haze which corrodes your roofing screws, causing them to weaken. Once this happens their performance is greatly affected over their lifetime.
Besides being caused by salt air, corrosion of roofing screws can also result from acids carried through the air from industry and chemical sprays, U.V. from the sun, or humidity in tropical or moist areas.
Roofing screws are generally overlooked as having a detrimental effect, and they are something that usually no-one notices until it is too late – and the roofing iron has to be replaced! Therefore, it is good policy to have the screws checked around every 5 years, as this will ensure that you keep on top of the problem of your roofing iron being affected by rusty screws.
Corrosion is usually associated with metals such as steel, zinc and aluminium, which are refined from ore. When air, water or salt are present, these metals will quickly corrode. Oxygen will cause oxides to form, resulting in corrosion, and therefore causing the metal to eventually be turned back into the ores from which they originated.
Roofs generally fall into Class 3, for ‘mild industrial and marine conditions’ – these are general living conditions; or Class 4, for ‘marine and moderately severe corrosive environments’ – living near the coast, or susceptible to industrial acids or chemical sprays. It is advised that stainless steel screws be used in Class 4.
So, if you live near the coast, or in areas where chemical spraying is prevalent, it is important to be aware of these classes, and to ensure you use the correct – and good quality – screws for the best protection.