Glazpartners 2026
Avoiding the costs of poor fastener selection and installation
Andy Holland, Technical & Marketing Manager at Rapierstar, highlights the importance of correct fastener selection and application during window and door manufacturing, installation and repairs.
The types of self-drilling screws used in PVCu window and door manufacturing and installation, and how they are used, are usually not the biggest concerns among fabricators and installers. However, making the wrong choices with these tiny components can often cause the most costly headaches, directly hitting profitability.
Unless self-drilling fasteners are selected correctly for the many different applications and profile systems, and installed as designed, the performance, operation, and long-term durability of the finished unit can be compromised. That’ s why a large part of our team’ s work is with fabricators across the UK and Ireland to help them optimise fastener selection and use.
Fastener focus, however, is not just a fabricator concern. If you are an installer,
you will already be aware of the different types of frame fixings available and how to use them, but what about the screws used to assemble the units? If you remove any screws during window or door installation, such as to temporarily detach a sash, or when completing a window repair, you also need to know how to make the right fastener choices.
This is why everyone should understand the most common reasons fasteners fail to meet expectations in a window or door assembly. Being better informed about where things may go wrong due to fastener choice and use can be helpful throughout the supply chain, from the
factory floor to a homeowner’ s repair.
Four common fastener issues in PVCu fabrication are as follows – depending on the application, these issues can affect structural performance, resistance to wind loading, security and the long-term retention of hardware:
1. SCREWS NOT ENGAGING PROPERLY WITH THE STEEL REINFORCEMENT
Drilling into thin steel reinforcement requires controlled axial pressure, not aggression. Keeping the driver aligned with the screw is critical, as even a small deviation reduces drilling efficiency and can prevent proper engagement with the steel.
2. EXCESSIVE DRIVER SPEED IS USED DURING FABRICATION
Another often-overlooked issue is using a driver with excessive RPM. Using a highspeed driver setting may feel efficient, but excessive rotational speed can generate excessive heat at the drill point. This can reduce cutting efficiency and potentially damage the point before it penetrates and connects with the steel reinforcement.
3. DRILLING CAPACITY AND SCREW LENGTH HAVEN’ T BEEN MATCHED TO THE APPLICATION
Drilling capacity relates to the overall thickness of material that the drill point is designed to penetrate. Screw length must also account for the overall material stack, including PVCu, steel reinforcement, hardware, brackets and packers, while still providing adequate thread engagement. Drilling capacity and screw length should always be matched to the material stack and the required thread engagement to ensure consistent performance.
4. USE OF IMPACT DRIVERS
Despite their popularity, impact drivers are often unsuitable for fixing into reinforcement. Their shock loading and torque spikes can damage drill points, strip the formed thread and increase the risk of head failure. Excessive final tightening torque can also overstress the fixing after drilling is complete. For controlled, repeatable installation, torque-controlled drill / drivers or production screwdrivers are generally preferable, as they let you manage both driver speed and final tightening torque more consistently.
THE KEY TO SUCCESS: CONTROL AND CONSISTENCY
Consistency in fastener selection, tool settings and installation methods delivers more reliable results than changing components without first identifying the root cause of a problem. After all, windows and doors are‘ systems’ formed of different materials and components, and the screws make a hugely important contribution within them.
Rapierstar supports this approach with application testing, Recommended Fixing Manuals, and factory Health Checks that help manufacturers select the correct fastener and establish consistent installation application settings.
www. rapierstar. com
12 OCTOBER 2026 CLEARVIEW-UK. COM