You don’t expect to see structural anchor failures on a building that is only six years old. For asset and facility managers, a recent handover date usually means you should be able to take overhead safety pretty much for granted. However, a recent site visit to an office car park proved that poor installation and the wrong material choices can cause critical issues much sooner than expected.
Our team was called out to test the overhead building services grid, which holds up the heavy network of Unistrut channels, LED light fittings, and cable trays. While this was meant to be a routine validation check, our initial walk-through showed that the fixing system had already begun to give way.
Finding structural failures on a practically new asset is alarming. Using calibrated Hydrajaws pull-testing rigs, we looked into why these anchors failed so early in their lifespan, why a standard test report wouldn't be enough to solve the problem, and how we fixed the issue on the spot at the client's request.
The Site Assessment: Uncovering the Failures
The objective of the site visit was routine validation. However, visual inspection quickly revealed that parts of the Unistrut system holding up the primary lighting fittings and service runs had visibly sagged and in some places, entirely pulled away from the concrete slab overhead. To determine the root cause, we used calibrated Hydrajaws pull-testing rigs to provide quantitative data which confirmed our worst-case scenario: a cascading series of structural anchoring failures.
The failures were driven by two distinct missteps made during the original construction phase.
1. Fixing Into Concrete Joints
The first major issue uncovered by our engineers was the placement of the fixings. A significant portion of the dropped anchors had been drilled directly into, or immediately adjacent to concrete joints.
When a traditional expansion anchor or drop-in anchor is set inside these zones, the concrete surrounding it is fundamentally unstable. As the joint opens and closes by fractions of a millimetre over time, the friction-based dynamic holding the anchor in place is compromised, leading to immediate slip and eventual pull-out under standard loads.
2. Corroded Carbon Steel Anchors
The second issue was material degradation. The multi-storey car park, while covered, was an open-sided structure exposed to fluctuating ambient humidity, seasonal temperature shifts, and exhaust fumes containing sulfur and nitrogen oxides.
The original installers had used standard yellow, zinc-plated, carbon steel expansion anchors. Over the years, atmospheric moisture and chemical exposure caused severe galvanic and uniform corrosion. The expansion sleeves had completely rusted, causing the metal to flake, lose its structural cross-section, and lose its grip against the internal walls of the drill hole. If left unchecked, the continuous dead weight of the lighting infrastructure meant a catastrophic, sudden collapse of the services grid was not just a possibility, it was an inevitability which was alarming considering the building was realtively "new" in terms of age.
Standard Testing vs. Our Service
In the site testing sector, most pull-testing companies operate strictly within a rigid silo: Arrive on site, conduct a test and provide a report on their findings.
While this fulfills a remit, it can leave a property manager or facilities director in a incredibly difficult and high-liability position if they find similar failures. The client is handed a piece of paper confirming that their ceiling infrastructure is structurally unsafe and at risk of collapse, but they are left with zero immediate engineering guidance on how to fix it. The risk remains active, the area must be cordoned off, and the client is forced to consult structural engineers, source alternative fixings, and hire secondary contractors to remediate the work.
At Certifix, we approach project safety differently. We believe that identifying a critical structural failure is only half the job; mitigating the risk immediately is the real objective.
The Solution: Speed, Performance, and Stainless Concrete Screws
Because we operate as both technical testing specialists and an experienced fixing supplier, we didn't just deliver bad news and walk away. Instead of leaving our client with an unsafe asset and an administrative headache, our technical team instantly calculated the correct remediation methodology. For this specific car park environment and concrete condition, the clear technical choice was to switch away from unpredictable friction-based expansion anchors entirely and opt for a hybrid solution.
Why Stainless Steel Concrete Screws and Resin?
We specified high-performance, A4 stainless steel concrete screws combined with an epoxy resin to replace the failed fixings. This hybrid approach delivered a dual-action mechanism, combining the immediate mechanical interlock of a concrete screw with the environmental sealing and high-load capabilities of a chemical anchor. This specific combination offered distinct structural advantages:
Unlike traditional drop-in or shield anchors, concrete screws do not rely on outward expansion force to grip the substrate. They feature an optimised thread design that cuts cleanly into the concrete matrix, exerting zero expansion stress on the concrete. When combined with an epoxy resin, the chemical completely fills any micro-cracks or voids within the distressed concrete slab, ensuring an even distribution of the load near dynamic slab zones or irregularities.
By specifying A4-grade stainless steel, the fixings themselves are inherently resistant to aggressive atmospheric conditions. Introducing the epoxy resin adds a secondary, critical line of defense: it completely seals the drilled hole against the ingress of atmospheric moisture, seasonal condensation, and corrosive exhaust emissions. The resin also prevents water from pooling in the overhead soffit holes, eradicating the risk of hidden internal corrosion.
While standard chemical anchors require extended curing times before they can accept a load, a hybrid screw-and-resin solution allows the screw to establish immediate mechanical hold.
The true value of our integrated approach came down to instant verification. Once installed, we immediately subjected the new installations to rigorous, on-site pull tests to prove the mechanical performance of the new fixings on the spot. Our recommended solution demonstrated that they easily surpassed the design load criteria without slipping, yielding, or damaging the substrate.
Zero Waiting. Risk Mitigated.
By combining on-site pull testing with immediate technical specification, this car park refit was turned around in a fraction of the time a traditional procurement route would take.
Instead of getting caught in an extended loop of waiting for engineering consultants, sourcing parts from separate suppliers, and dealing with prolonged closures of vital staff parking bays, the client received an immediate technical resolution. We didn't just diagnose the issue; we physically installed the high-performance resin-screw fixings, tested them to their limit on-site, and handed back a certified, structurally sound environment.
If you suspect that your overhead services, suspended grids, or heavy fixtures are relying on incorrect or failing anchor specifications, especially in high-vibration or exposed environments, don't wait for a structural failure to highlight the issue.
Does this sound familiar? Do you find yourslef in similar situations on you projects?
Get in touch with our technical team today to arrange a precise site pull test. We will provide you with clear, quantitative data on your current fixings and, if there is an issue, working together with you, we will deliver the engineered solution.
