Conservation Rooflights: Navigating the Challenges of Steel Frames

Steel framed conservation rooflights, popular in both period and contemporary projects, offer an unparalleled glass-to-frame ratio, maximising natural light and ventilation.

Particularly favoured for Listed buildings or conservation areas, they provide an authentic Victorian design. However, beneath their aesthetic appeal lies a critical concern – rust. This article delves into the intricacies of steel framed rooflights, emphasising key considerations in the specification process.

Material Choice

Mild steel, prevalent for its affordability and versatility, dominates conservation rooflight construction. Often coated to prevent rust, these rooflights rely on the coating for protection. However, any damage during installation compromises this defence, hastening corrosion. A notable alternative is the 316 marine-grade stainless steel frame, recognised for superior corrosion resistance compared to carbon steel.

Corrosion Dynamics

Carbon steel and stainless steel both contain iron, which oxidizes when exposed to the environment, resulting in rust. The key difference lies in chromium content; stainless steel, with added chromium, forms a protective chromium oxide layer, offering enhanced corrosion resistance. Stainless steel emerges as the preferred choice for those prioritising corrosion resistance.


Conservation Rooflights: Navigating the Challenges of Steel Frames Stella Rooflights

Protective Coatings

Steel framed rooflights employ powder coating or wet spray paint finishes. Unlike mild steel, where the coating is vital for protection, a 316 marine-grade stainless steel rooflight primarily utilises coating for aesthetic purposes. Powder coating, applied electrostatically and cured under heat, provides durability, especially in the face of impact, moisture, and UV light. The application’s resilience depends on environmental classification (C1 to C5), often standardised to C3 for urban and industrial atmospheres.

Maintenance Imperative

Powder-coated rooflights require maintenance to preserve aesthetics and functionality. Accumulated dirt and mechanical damage impact design life. Regular inspections, particularly in C3 environments, are necessary for longevity. Neglecting maintenance jeopardises warranties, leading to potential rooflight failure.

Longevity and Cost Considerations

Mild steel rooflights are prone to rust, exacerbated by neglecting maintenance guidelines. Coastal and inaccessible locations demand meticulous care, emphasising the longevity benefits of stainless steel. While the initial cost of stainless steel may be higher, the absence of repair or replacement costs makes it a cost-effective choice over the product’s lifespan.

Conservation Rooflights: Navigating the Challenges of Steel Frames Stella Rooflights

Specifier and End-User Awareness

For specifiers, prioritising steel type over appearance is crucial. Consider the property’s location, potential coating-affecting factors, and client responsibilities for maintenance. Given the limited warranties and stringent maintenance requirements, specifying 316 marine-grade stainless steel from the outset can pre-emptively address potential issues.


When specifying steel-framed rooflights, whether for traditional or contemporary projects, meticulous consideration of steel type is paramount. Beyond appearance, the location’s impact on coating life and client responsibilities for maintenance should guide the specifier.

Opting for 316 marine-grade stainless steel, despite the initial cost, ensures a resilient solution that withstands the test of time, minimising the risk of catastrophic material failure associated with mild steel rooflights.


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The Ultimate Guide to Conservation Rooflights

Independent expert advice for architects, builders and homeowners