How does an undercut anchor work?
The principle behind concealed, positive-locking fixing of façade panels.
Key facts at a glance
- A cylindrical hole with a undercut is drilled into the rear of the panel.
- The anchor is set into this undercut to create a positive-locking connection.
- The visible face of the panel remains free of fixing points.
- Hole geometry, anchor, embedment depth and panel material must be coordinated.
- The applicable approvals and installation instructions are decisive.
Positive locking at the rear of the panel
An undercut anchor mechanically fixes a façade panel through a specially shaped blind hole in its rear side. The hole is cylindrical at first and widens at its base. During installation, the anchor sleeve expands into this geometry. This creates a positive-locking connection: loads are transferred into the panel material through the undercut without penetrating the visible face.
From the drilled hole to the substructure
A panel bracket or another connecting element is attached to the installed anchor. This connects the panel to the substructure of the ventilated rainscreen façade. Dead load and wind loads are transferred from the cladding through the anchor and panel bracket into the supporting system. The arrangement and number of fixing points depend on panel format, material properties, edge distances, loads and the applicable technical evidence.
With the KEIL system, the cylindrical hole and undercut are produced using a coordinated drilling tool. The KEIL undercut anchor is then installed with controlled displacement. The matched geometry of hole and anchor supports reliable installation, but does not replace the specified inspection of hole dimensions or compliance with the relevant approval or ETA.
Design as a system task
Undercut technology is not an isolated component. Panel material, residual panel thickness, embedment depth, fixing element, connection detail and substructure must be considered together. Only this coordination creates a load-bearing and durable concealed fixing. Any deviation from the specified system components or installation parameters therefore requires technical assessment.
Conclusion
An undercut anchor transfers loads through a positive-locking connection in a undercut hole on the rear of the panel, enabling concealed façade fixing. Safe performance depends on the precise coordination of all system components.
