In order to answer this question, it’s important to know what is meant by “Structurally Bonded”.
‘Structurally bonded’ refers to the load-bearing structural adhesive used to form a bonded joint, capable of holding two or more substrates together under stress. In high-quality rooflights, this is the bond between the glass units or the glass unit and its framework.
Structural bonding is generally undertaken in controlled factory conditions during the assembly of the rooflight and when done correctly, will ensure the glass units and the frame will not become detached or move apart, be that:
When structurally bonded with structural silicone like Dow Corning 995, the rooflights glass and framework will expand and contract together regardless of temperature changes.
This means when a rooflight isn’t structurally bonded, there is the potential for the glass to move in its frame. This could happen once it’s installed due to the suction effect of high winds on the glass, or perhaps as it’s being transported to site, or by storing it leaning against a wall, or even by manhandling the rooflight unevenly onto the roof.
With modern-day flat roof rooflights having sheer external surfaces, they almost completely rely on the quality of the external perimeter seal between the glass and the frame. So, in any of the examples given, movement of the glass in the frame can cause the perimeter rooflight seal to become detached from either the glass or the frame, in turn leading to every owner’s worse fear – leaks.
So, in answer to the question, let’s pose another question:
Why risk having a rooflight leak when there are well-made, structurally bonded products on the market that won’t?
So you may be wondering how to check this – How do I know when a flat rooflight is structurally bonded? If the rooflight manufacturer says you cannot lift its product by the glass, the glass can’t be structurally bonded to the framework so the product isn’t structurally bonded!
All Duplus rooflights and roof lanterns are structurally bonded. Every product has been designed and is individually tested to ensure full compliance with The Dow Corning Quality Bond Scheme through regular auditing.