Explore the durability and maintenance needs of steel framed rooflights. Learn why 316 marine grade stainless steel is the preferred choice.
An insight into steel rooflights and the issue of rust
It is widely acknowledged by both professionals and consumers that steel is the premier choice for conservation rooflights. Able to achieve great strength, while retaining a thin framework and a low profile finish, steel framed rooflights provide an appearance that modern alternatives can only dream of replicating.
Glass to Frame Ratio
Commonly specified in both period and contemporary projects, a steel framed rooflight design normally offers a superior glass to frame ratio, when compared with modern bulky rooflights. This extra access to both natural light and ventilation is one of the reasons why steel frames remain a popular choice. In certain applications, such as Listed buildings, conservation areas or sensitive replacements, steel framed rooflights should be the only choice, as these offer the most faithful replica of an original Victorian design.
Maintenance Required
The saying goes that ‘beauty is only skin deep’, however, when choosing or specifying rooflights it is important that you look beyond appearance and take into consideration the longevity and maintenance requirements of the materials used.
While the appearance of a steel framed rooflight is second to none there is an inherent shortcoming in the use of steel, particularly when used in a roof, and that is the potential for it to rust.
The most common steel used for rooflights is mild steel (sometimes referred to as carbon steel) and in their naked form these materials offer virtually no resistance against rusting and will begin to corrode from the moment it comes into contact with the atmosphere.
Aren’t all steel rooflights the same?
Mild steel (iron containing a small percentage of carbon, strong and tough but not readily tempered), also known as plain-carbon steel and low-carbon steel, is now the most common form of steel for conservation rooflights, because of its relatively low price and versatility.
Almost all rooflights are produced with some type of paint coating, which is designed to keep the main structure away from atmospheric conditions; in the case of mild/carbon steel rooflights this prevents them from rusting. It is worth noting that mild/carbon steel framed rooflights are totally dependent on the paint to stop the frames rusting and even the slightest damage during installation can signal the demise of your rooflight.
Stainless Steel
One of the ways to avoid the risk of rusting associated with steel framed rooflights is to specify a 316 marine grade stainless frame.
The most obvious difference between carbon steel and stainless steel is the ability to resist corrosion, with stainless steel (as the name implies) being the more corrosion resistant material. Both carbon steel and stainless steel contain iron, which oxidizes when exposed to the environment, creating rust. It is the presence of added chromium in stainless steel, which makes it more corrosion resistant than carbon steel.
Without wishing to overcomplicate the point, the chromium will attach itself to oxygen more readily than iron, but when the chromium attaches to the oxygen it creates a chromium oxide layer, which protects the rest of the material from degradation and corrosion. Carbon steel does not have enough chromium to form this chromium oxide layer, allowing oxygen to bond with the iron, which results in iron oxide, or rust. Therefore, if corrosion resistance is a key factor in your choice of specification, stainless steel has to be the way to go.
Roof Window Protective coatings
Steel framed rooflights will usually have a powder coated finish as this offers a better final appearance than wet spray alternatives. Unlike mild/carbon steel, which relies on the coating for complete protection, a 316 marine grade stainless steel rooflight mainly has the coating for aesthetic purposes.
Powder coat is a type of coating that is applied as a free-flowing, dry powder. Unlike most conventional liquid paints, which are applied via an evaporating solvent, powder coating is typically applied electrostatically and then cured under heat. Powder coating is mainly used for coating of metals and is designed to create a finish that is tougher than conventional paint.
High Quality Finish
Done correctly powder coating provides a high-quality finish, which gives metalwork a more durable layer than liquid paints can offer, while still providing an attractive appearance. Applied to the right environment criteria, powder coated rooflights are more resistant to diminished coating quality as a result of impact, moisture, ultraviolet light, and other extreme weather conditions.
C1 to C5
Powder coat applications should always be applied to a standard suitable for the location of the rooflight. The environment in which a rooflight is located is classified from C1 to C5 with the lower end of the scale (C1) for internal use in buildings with clean atmospheres, right up to marine coastal/industrial with aggressive atmosphere (C5).
The most common application for steel framed rooflights is to a C3 standard, which covers urban and industrial atmospheres with moderate sulphur dioxide pollution. While this should give a good standard of protection for most places in the UK there are a number of factors, which could affect the lifespan but are often overlooked.
Coastal Properties
It is easy to identify a property which is within 5km of the coast and specify the required marine coating, however if a property is located close to a road which is heavily gritted during the winter months this could potentially be as aggressive and corrosive to the powder coating as a property which is sited within a coastal environment.
Ultimately identifying the right classification is not always as straightforward as looking up a postcode and careful consideration should be given to any environmental factors which may impact on the lifespan of the protective coating. Choosing the right durability is a question of cost but if the system doesn’t last long enough, rectification could be expensive for the end user.
To remove any risk and to make this confusing process easier, all Stella rooflights are painted to a C5 classification as standard so regardless of where your project might be, you can be assured of the highest level of paint quality at all times.
Paint coats are not magic coats!
Industrial coatings, like car paint, need cleaning and maintenance. Dirt and mechanical damage affect their lifespan. Regular inspections and touch-ups are essential.
Maintenance is crucial not just for aesthetics but to prolong rooflight life. Lack of maintenance can void warranties. Rooflights in C3 environments need annual care, while coastal C4 locations require maintenance every three months.
Steel rooflights often rust due to neglected maintenance. It’s crucial for specifiers and end-users to follow guidelines to extend product life. Stainless steel, though initially costlier, offers long-term savings with reduced repair needs.
Conclusion
When specifying steel framed rooflights, consider the type of steel, not just the appearance. Factor in the property’s location and any elements that might affect coating life. Consider your maintenance duties and check with suppliers about care requirements.
Many rooflight companies offer only a 12-month warranty with strict maintenance requirements. To avoid potential issues, consider specifying 316 marine grade stainless steel from the start. Although all rooflights need some care, stainless steel is less likely to fail catastrophically if maintenance lapses.
