Why the system has to be designed and manufactured as one and what happens to performance when it isn't

I started on the shop floor of my father's glass and aluminium factory when I was in my twenties. I spent eleven years there before founding Balconette in 2004, and I have spent the two decades since designing, manufacturing and installing glass balustrade and balcony systems from our factory in Surrey.

That background gives me a particular way of looking at how buildings go together. Or rather, how they go wrong.

Most roof terrace failures are not failures of individual products. The membrane performs. The balustrade is structurally sound. The deck surface is fit for purpose. The failure is at the interface between them - at the point where one trade's work ends and another's begins, where the assumptions made in one part of the design are invisible to the engineer working on the next part, where the system that was specified as a coherent whole has been assembled from components that were never designed to work together.

I have seen this repeatedly over twenty years. And it is why, when I set out to design BalcoDeck®, I made a decision that shaped everything that followed: it would be designed, engineered and manufactured as a complete system - one company, one facility, one certificate of compliance - or it would not work.

What system coherence actually means

When you design a glass balustrade, you make assumptions about the base fixing. The glass thickness specification, the interlayer type, the panel dimensions - all of these are calculated against an assumed base moment capacity. If the base fixing changes, those assumptions become wrong. The structural glass specification is no longer valid for the actual installation.

In a penetratively-fixed balustrade assembled from separate suppliers, this mismatch is routine and largely invisible. The glass supplier specifies glass to a certain load. The fixing supplier provides a fixing rated to a certain capacity. The waterproofing contractor provides a membrane. The deck installer provides a deck. A main contractor brings them together on site. Nobody has modelled the complete load path from glass panel to roof structure in a single calculation. Nobody has verified that the assumptions made at each stage are consistent with those made at every other.

The result is a system whose actual structural performance is determined by the weakest link in a chain that nobody has traced end to end.

With BalcoDeck®, the calculation is integrated from the start. The wind load assessment for a specific site determines the base moment demand. That base moment demand determines the platform geometry. The platform geometry determines the loads - and the system is designed to ensure that the substructure bears and resists these loads within safe limits. All this is done without penetrating or structurally compromising the waterproofing layer beneath the BalcoDeck® substructure. The glass specification is calculated against the actual base stiffness of the platform, not an assumed value. The deck surface loading is included in the overall structural model.

Every component is calculated against every other. The system is coherent because the engineering is coherent. And the Certificate of Compliance we provide at the end of every installation documents that coherence - structural loads, wind loads, fire rating, building regulations compliance and material specifications, in a single document from a single source.

What happens when the system is not coherent

The most common failure point is the penetration interface - the sealed junction between the balustrade post fixing and the waterproof membrane. That interface is doing multiple things simultaneously: creating a watertight seal, accommodating differential thermal movement between the steel fixing and the membrane, and carrying any load path discrepancies that the structural engineer did not account for.

That is a lot to ask of a bead of sealant with a service life shorter than the building it is sealing.

The failure does not happen on day one. It happens at year three when the sealant has begun to fatigue from thermal cycling. Or year five when the first water ingress event occurs - often diagnosed as membrane failure, because that is the easier explanation. Or year eight when the structural consequence of repeated wetting and drying begins to manifest in the fabric of the building below.

By that point, the waterproofing contractor has been paid and moved on. The balustrade supplier has fulfilled their contract. The deck installer has no ongoing liability. The architect is holding PI exposure for a defect that none of the parties responsible for the individual components will acknowledge as theirs.

The single-source model

One company. One system. One Certificate of Compliance.

This is not a marketing proposition. It is the structural logic of how you build something that performs over the life of a building rather than over the life of a warranty period.

When BalcoDeck® surveys a roof, the engineer assessing the structural loads is the same engineer who will design the platform to carry them. When the platform is manufactured in our Surrey factory, it is made to the drawings produced by the engineer who designed it. When our team installs it, the installation follows a methodology that the design engineer has specified and that will be documented in the Certificate of Compliance.

If there is a discrepancy between the structural assessment and the conditions on site, we know immediately - because the same organisation is responsible for both. There is no gap between design and execution for a mismatch to hide in.

Thirty years of manufacturing has taught me that the most expensive failures are the ones that were inevitable from the first day, but invisible until it was too late to fix them cheaply. The roof terrace industry has been building those failures in for twenty years.

BalcoDeck® is the alternative.