by Paul Trace, Director of Stella Rooflights
Specifying rooflights for conservation projects is never a box-ticking exercise. In fact, the rooflight is often one of the most scrutinised elements in any planning application involving a listed building or conservation area. For architects, this makes the distinction between ‘conservation-style’ and truly conservation-appropriate rooflights more than just semantics, it’s the difference between a smooth planning process and a frustrating refusal.
In a market saturated with products that mimic the look of traditional rooflights, it’s tempting to focus solely on appearances. However, true conservation demands more than a surface-level resemblance. To meet both regulatory expectations and the design integrity of heritage architecture, rooflights must be carefully evaluated on their materiality, construction, detailing, and compatibility with historic building fabric.
The Illusion of Authenticity
Over the past decade, the term “conservation-style rooflight” has become a catch-all label, used liberally across the construction industry. Many modern products adopt basic visual cues (with varying degrees of success) – a black powder-coated frame, a central glazing bar, flush installation – to achieve the appearance of a traditional cast-iron rooflight.
However, when it comes to listed buildings and sensitive heritage sites, appearances aren’t everything. Conservation officers are increasingly wary of imitation products that fail to replicate the subtle nuances of historic detailing or that compromise the character of the building in material or proportion.
For example, many off-the-shelf conservation-style rooflights are based on aluminium frames, which while lightweight and cost-effective, may lack the structural authenticity and durability expected in historically sensitive contexts. Others use applied glazing bars, often stuck on or sandwiched between glass layers, which can distort sightlines and fail to replicate the depth and integrity of traditional rooflight design.
What looks convincing at first glance may not withstand the scrutiny of heritage specialists, nor deliver the long-term performance and finish that architects and clients expect.
Planning Officers Are Looking Closer
It’s worth noting that planning scrutiny of rooflight specifications has evolved in recent years. Conservation officers (quite rightly) no longer accept the simple addition of a glazing bar as a ticket to approval. There is greater awareness of construction methods, profiles, and proportions.
A flush fit is now considered a minimum requirement. Beyond that, officers may ask:
- Does the product replicate the fine, slim steel profiles of a traditional Victorian rooflight?
- Is the glazing bar structural or merely cosmetic?
- Is the internal finish appropriate to the surrounding building materials?
- Can the rooflight accommodate modern performance standards without compromising on historical accuracy?
Architects must be prepared to answer these questions with confidence. That means understanding more than just product codes, it means knowing how rooflights are made, how they sit in the roof, and what makes them genuinely compatible with heritage buildings.
Material Matters
A key differentiator between true conservation rooflights and their lookalike counterparts lies in materiality. Traditional rooflights were made from cast iron or steel, set directly into the roof structure, often without an internal lining.
Modern equivalents must meet today’s performance standards for insulation, condensation control, and weathering, but they should do so without sacrificing material authenticity. High-grade stainless steel, for instance, offers a corrosion-resistant, slim-profile alternative to traditional ferrous metals, maintaining visual continuity while improving longevity.
Likewise, internal linings play a more significant role than often appreciated. In many heritage projects timber is the predominant internal material, whether exposed rafters or timber-clad ceilings. A genuine conservation rooflight should offer a hardwood liner that visually complements its environment. Too often, architects discover too late that the internal finish of a rooflight is plastic or bare aluminium – jarring with the character of an exposed timber ceiling or heritage plasterwork. By then, it’s too late to change.
The Importance of Section and Profile
Historic rooflights were typically made with minimal framing, set flush or nearly flush with the roofing material, often with delicate, hand-fabricated profiles. Modern products that seek to replicate these rooflights must pay equal attention to proportion and section, especially as viewed from the exterior.
Deep or bulky sections can appear alien on a slate or tile roof. Capping details, edges, and visible hinges must all be considered in terms of visual weight. True conservation rooflights prioritise slenderness and shadow lines, creating a light touch that respects the building’s roofscape.
Glazing bars, when required, should ideally be structural, not simply aesthetic add-ons, and follow the same principles. A stuck-on bar may give the illusion of division but lacks the depth and articulation of traditional glazing.
Going Bespoke When Necessary
One of the challenges architects often face in conservation projects is the lack of standardisation in existing roof openings. Historic buildings rarely conform to modern module sizes, which can make off-the-shelf rooflights a poor fit, either visually or physically.
This is where a bespoke approach becomes not just desirable, but essential. Made-to-measure rooflights allow architects to match existing openings, align glazing bars with fenestration, or replicate original details more accurately. While bespoke manufacture may come with a higher upfront cost, it often pays dividends in planning success, aesthetic coherence, and long-term performance.
It also ensures that critical technical details – such as insulation values, ventilation options, or solar control glazing – are specified to meet modern requirements without compromise.
British Craftsmanship and Cultural Continuity
Another critical, but often overlooked, factor in conservation specification is the origin of manufacture. In an era of global supply chains, many so-called conservation rooflights are produced overseas, far from the cultural context and architectural traditions they aim to serve. While cost may be the driving factor, it’s worth asking: is it appropriate to outsource our built heritage to anonymous factories in distant countries, disconnected from the very history we’re trying to protect?
British manufacturing still plays a vital role in the conservation sector, offering not only quality craftsmanship and shorter supply chains, but a deeper understanding of British architectural heritage. Supporting UK-based fabrication helps maintain skills, ensure accountability, and uphold standards – all of which are crucial when working on buildings of historic or national importance.
For architects and specifiers, this goes beyond patriotism. It’s about stewardship. Choosing a UK-made conservation rooflight is a vote for quality, context, and continuity – values that lie at the heart of responsible conservation practice.
Beyond Aesthetics, Towards Integrity
For architects working on heritage and conservation projects, specifying a rooflight is not just a question of what looks right, it’s about what is right. True conservation rooflights respect the past not only in form, but in substance. They combine traditional aesthetics with modern performance, without resorting to superficial mimicry.
As planning departments become more rigorous, and as clients expect more from their investments in heritage, the pressure is on architects to make informed, intelligent choices. Choosing the right rooflight is a small but vital act of architectural integrity – one that respects both the spirit of the past and the demands of the present.
To find out more about genuine conservation rooflights for your project
contact the Stella Rooflight team on
01794 745445
