It is a widely accepted that mild/carbon steel will start to rust the moment that it comes into contact with the atmosphere. Put that material in an environment with an elevated salt content and the corrosion will be both fast and significant.
It is therefore essential that any protective coating is not only applied correctly but also maintained regularly as without that thin layer of protection, the metal will oxidise and the corrosion process will begin. The paint coatings applied to a mild/carbon steel rooflight is the only thing stopping that product from rusting away and you might be surprised to find out what level of maintenance is required to keep any guarantee valid.
Whilst there are differing paint applications available depending on the location of your property, you tend to find that the requirements of maintaining your rooflight actually increase the better the paint is. For example, a standard rural location which is over 5km from the coast or a salt water estuary would be classed as a C3 environment. This is a fairly typical standard of paint for steel rooflights and you would be expected to clean the paintwork on an annual basis.
Now if your property is in a coastal location (less than 5km from the coast) then the environment is classed as C4. This means that your rooflight will require a better paint coating to repel the higher levels of salinity in the atmosphere. While a C4 paint application offers greater protection that that of a C3 coating, you could be expected to clean it up to four times a year in order to keep your guarantee valid.
The external coatings of rooflights are normally hard to reach and quite often leaning out of a top hung casement offers neither sufficient access nor the safety to undertake the job properly. If you have a fixed casement this task is made even more complicated. So essentially if you are not able to get to the outside of your rooflight to clean it at the required intervals, not only are you likely to find that your guarantee is no longer valid, there is a good chance that it will also be rusting as the paint deteriorates.
While a Stella rooflight is bound by the same cleaning requirements as other products with industrial coatings, the consequences of not maintaining our paint system are far less severe than rooflights produced from mild/carbon steel. Not only are Stella rooflights manufactured from a long lasting 316 stainless steel but our paint specification is significantly better than anything else being offered on the market.
A Stella rooflight is supplied with a C5 paint coating as standard (which is good news for those of you wanting to fit a rooflight in a lighthouse). For everyone else, this means that in a C4 environment you could expect the paint to last 15-25 years which is a significant improvement on anything being offered by other steel rooflight manufacturers.
Even naked without a paint coating, a Stella rooflight will outlast all other painted mild/carbon steel rooflights. This is because carbon steel lacks the corrosion-resistant properties of its stainless steel counterpart. Carbon steel is at high risk of rusting and corrosion when exposed to moisture. Even small amounts of moisture, including moisture vapour in the air, can cause carbon steel to rust, which can’t be good for a rooflight situated on the roof in the UK. Furthermore, carbon steel is less ductile than stainless steel so has less ability to withstand tensile stress.