In contemporary façade design, aluminum cladding systems are often specified with increasingly large or slender panel formats. To ensure structural integrity under wind loads and other environmental pressures, metal stiffeners are routinely introduced to limit deflection and distribute stresses. However, recent project submittals and site inspections have revealed a recurring inadequate or incorrect fixation methods for these stiffeners, particularly the reliance on weather sealants or structural adhesive tapes as primary restraint mechanisms.
This article outlines the risks associated with such practices, explains the performance limitations of non-mechanical fixings, and provides clear guidance on acceptable solutions in accordance with industry standards and long-term performance expectations.
It has become increasingly common to observe metal stiffeners bonded to aluminum cladding panels using weatherproof sealants or double-sided structural adhesive tapes, particularly in value-engineered solutions or accelerated construction programs. While these materials serve important roles in façade systems—such as weatherproofing and joint sealing—they are not suitable for structural or load-bearing applications.
In many instances, weather sealants are applied in a thin, superficial layer, intended merely to hold the stiffener in place. However, this approach fails to provide adequate adhesion. Without the correct bond-line thickness, surface preparation, and material compatibility, the sealant cannot guarantee a reliable or lasting bond between the stiffener and the panel substrate.
Provide high initial adhesion under controlled conditions. However, they present significant drawbacks in external façade use:
The consequences of relying on these materials includes:
To ensure the long-term structural reliability of cladding panels with metal stiffeners, the following best practices are strongly recommended:
Only where mechanical fixing is technically unfeasible, approved structural silicone sealants may be used. These must be:
Before approving or executing stiffener fixation methods, project teams should verify:
Façade systems rarely fail catastrophically overnight. Instead, they deteriorate gradually, often due to overlooked or undervalued details such as improper stiffener fixation. In a climate where performance, durability, and safety are under increasing scrutiny, treating stiffeners as structural elements is not optional, it is essential. As the industry pushes toward more efficient and sustainable façades, attention to detail at the micro level, including proper bonding and fixing methods, remains a critical determinant of long-term success.
AESG is an international Consultancy, Engineering and Advisory firm committed to driving sustainability in the built environment and beyond. With the highest calibre leadership team in our field, we pair technical knowledge with practical experience to provide hands-on, bespoke strategic solutions to our clients.
We have one of the largest dedicated specialist consultancy teams working on projects within the building, urban planning, infrastructure and strategic advisory sectors. With decades of cumulative experience, our team offers specialist expertise in sustainable design, sustainable engineering, MEPF, fire and life safety, façade engineering, commissioning, digital delivery, waste management, environmental consultancy, strategy and advisory, security consultancy, cost management and acoustics. Our prestigious portfolio demonstrates our extensive capabilities and our ability to consistently deliver best in class solutions to some of the industry’s most complex technical challenges.
Senior Associate Façade Consultant, AESG
Gennaro is a Senior Associate Façade Consultant with over 20 years of experience in curtain wall, stick system, doors & windows, structural point fix glass system.
Prior to joining AESG in 2021, Gennaro has worked as a Project Design Manager for one of the worldwide leading contractors in the engineering, project management, manufacturing and installation of architectural envelopes and high-end interior fit-out.
With half of his career spent in the UAE, he followed several iconic projects located in different countries like UAE, Saudi Arabia, Azerbaijan and Malaysia. In his role he was fully involved in managing the relations with clients, architects, and main contractors from the technical and economical point of view.
For further information relating to specialist consultancy engineering services, feel free to contact us directly via info@aesg.com
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