Rooflights, Roof Windows and the End of ‘Marking Your Own Homework’
Rooflights, Roof Windows and the End of ‘Marking Your Own Homework’
Richard Bates, MD of Buccaneer Solutions discusses why the construction products industry must embrace greater transparency before regulators force the issue
For many years the construction products industry has operated on a remarkably high degree of trust.
Architects have trusted manufacturers to understand the regulations that apply to their products. Building control professionals have trusted that published performance data accurately reflects how products have been tested. Contractors have trusted that a Declaration of Performance genuinely demonstrates compliance. And, by and large, manufacturers have been left to determine for themselves whether the evidence they hold is sufficient to support the claims they make.
In many respects, the industry has been marking its own homework.
That may sound like a harsh assessment, but it reflects a reality that is now changing rapidly. The regulatory environment surrounding construction products has evolved significantly in recent years and, with the Office for Product Safety and Standards (OPSS) assuming an increasingly proactive enforcement role, manufacturers should expect their technical evidence to receive a level of scrutiny that simply did not exist a decade ago.
This is not about creating additional bureaucracy or making life more difficult for responsible manufacturers. It is about restoring confidence in an industry where performance claims must increasingly be supported by robust, independently verifiable evidence rather than assumption, historic practice or clever marketing.
Few product categories illustrate this challenge better than roof glazing.
More than just terminology
The terms rooflight and roof window are frequently used interchangeably throughout the construction industry. Browse manufacturers’ websites and brochures and it is easy to understand why confusion exists. Yet from a regulatory perspective, the distinction is fundamental.
The principal difference is not the appearance of the product but the way it is installed. A rooflight is generally assessed as a product installed horizontally, typically above a flat roof on an upstand or kerb. A roof window, by contrast, is installed within the pitch of the roof itself and is therefore assessed in the vertical plane.
At first glance this may appear to be little more than a technical nuance. In reality, it is anything but.
The orientation of glazing has a direct influence on thermal performance. The very same product can produce markedly different U-values depending upon whether it is assessed horizontally or vertically. The difference is not insignificant; it can fundamentally alter the declared thermal performance of the product.
This is why product classification matters.
It is not simply a question of what a manufacturer chooses to call a product. It is about ensuring that the product has been tested in the correct orientation, against the correct designated standard and for its intended application. As Building Regulations continue to demand ever lower U-values, that distinction becomes increasingly important.
Testing has moved on
The challenge facing the industry is compounded by the fact that testing methodologies have themselves evolved.
Historically, there was genuine ambiguity surrounding the assessment of roof glazing products. The treatment of upstands and kerbs, the distinction between in-plane and out-of-plane installations, and precisely which parts of the assembly should be included within thermal calculations were not always interpreted consistently across the industry.
In some instances, elements of the product lying beyond the structural opening or outside the line of the rafters were treated differently from the way they would be assessed today.
Over time, designated standards, recognised guidance and UKAS-accredited testing procedures have developed considerably. Much of the uncertainty that previously existed has now been removed, providing manufacturers with a far clearer framework for demonstrating compliance. That evolution, however, raises an important question.
How many manufacturers are still relying on testing undertaken under historic methodologies without asking whether that evidence remains appropriate for today’s products, today’s regulations and today’s Declarations of Performance?
Possessing a test report does not automatically demonstrate compliance
Compliance is about evidence, not marketing
It has become increasingly common for manufacturers to compete on headline U-values, often reducing an extremely complex assessment process to a single figure within a brochure or on a website. Yet a U-value, on its own, tells only part of the story. Architects should not simply be as king what the U-value is. They should be asking how it was obtained.
Was the product assessed in the correct orientation?
Was the complete assembly included within the assessment?
Was the testing undertaken by a UKAS-accredited laboratory?
Does the evidence relate to the product actually being supplied?
Does the Declaration of Performance accurately reflect the intended use of that product?
Only by asking those questions can specifiers be confident that they are making like-for-like comparisons
The days of marking your own homework are coming to an end
For too long, some areas of the construction products industry have relied upon the assumption that if nobody asks the question, nobody needs to provide the answer, however, that culture is changing.
The OPSS has been given a significantly enhanced mandate to oversee construction product compliance and, importantly, the resources to exercise those powers. Increasingly, the regulator is looking beyond product brochures and headline performance claims to examine the evidence that sits behind them.
Technical files, UKAS-accredited testing, factory production control documentation and Declarations of Performance are becoming central to demonstrating that products have been lawfully placed on the market and that the performance being claimed can be substantiated. Manufacturers should not assume that historic testing, outdated methodologies or legacy documentation will automatically satisfy today’s regulatory expectations. If challenged, they must be able to demonstrate that the evidence they hold remains appropriate for the products they continue to sell.
Where they cannot, regulators have the ability to require corrective action and, where appropriate, prevent products from continuing to be placed on the market until compliance can be demonstrated.
For responsible manufacturers, this should not be viewed as a threat. It should be welcomed as greater scrutiny creates a more level playing field by rewarding those businesses that have invested properly in product development, independent UKAS-accredited testing and transparent Declarations of Performance, while making it increasingly difficult for unsupported claims to persist unchecked.
Ultimately, this is not about catching manufacturers out, itis about ensuring that architects can specify with confidence, contractors can build with confidence and clients can purchase products knowing that the performance being claimed has been independently evidenced rather than simply asserted.
The era of manufacturers marking their own homework is drawing to a close and the companies that recognise that today will almost certainly be the ones leading the market tomorrow.
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Stella produces exceptional rooflights that combine a flush fitting profile, while utilising the very best of materials, and has become the first choice for discerning clients looking to bring natural daylight into their living spaces through premium quality rooflights.
