Large Slabs on Facades: How Engineering Prevents the Risk of Detachment

Perspective detail of the ventilated façade made of large-format stoneware. The view from below highlights the precision of the installation and the minimalist aesthetic achieved by concealing all the utilities behind the ceramic cladding.

Contemporary architecture increasingly favors the use of continuous, clean surfaces with a strong visual impact.

In this scenario, large-format ceramic and porcelain stoneware slabs have become the undisputed protagonists of building envelope cladding. However, this aesthetic evolution must be supported by rigorous structural engineering. As the size of the modules increases, the physical and mechanical stresses to which the façade is subjected also increase exponentially.

Ensuring maximum safety over time and eliminating the risk of detachment at its source is a challenge that does not allow for approximations or standardized solutions, but requires a customized engineering approach, the fruit of thirty years of experience in the field.

Risk Factors: What Makes a Big Plate Stress?

An exterior façade is a living element, constantly exposed to atmospheric and dynamic forces. Underestimating these forces compromises the integrity of the structure. The main risk factors include:

• Thermal Changes and Expansion: Facades are subject to constant temperature changes (day/night, summer/winter). The materials of the exterior cladding and the metal substructure have different thermal expansion coefficients; the engineering must absorb these relative movements without generating internal stresses.

• Wind Action and Load: The thrusts and, especially, the depressions caused by the wind exert a constant tensile force on the panels. The larger the panel, the greater the "sail" effect that the fastening system must counteract.

• Structural Movements of the Building: Settlements of the reinforced concrete load-bearing structure or operating loads can transfer deformations to the exterior envelope if it is not properly connected and released.

The VM Group Approach: The Total Safety of Structural Glue Fixing

Application of double-sided tape on the substructure of the ventilated facade

Today, the use of latest-generation structural adhesives represents the highest level of safety for façade cladding with large-format panels. VM Group Srl uses bonding systems (developed in close partnership with market leaders such as Mapei) that boast a certified durability of more than 25 years (the minimum guaranteed for ETA certification), tested in salt spray and under extreme thermal stress cycles.

Unlike older systems, chemical fixing offers continuous hold: by applying the adhesive to multiple vertical profiles arranged along the height of the panel (for example, on 3-meter modules), the substrate is evenly distributed. This eliminates the stress concentration points typical of mechanical hooks alone and ensures that, even in the event of accidental breakage of the ceramic, the fragments remain firmly anchored to the supporting structure without any risk of falling.

The integration of an additional mechanical hook is therefore intended as a safety redundancy, introduced primarily for greater heights or at the express request of the Construction Manager (DL).

Comparative Analysis of Anchoring Systems for Large Slabs

The choice of fastening technology depends on the building's height, wind exposure, and the specific aesthetic requirements of the client or designer. Below is an overview of the main solutions:

Fixing System	Technical Features	Aesthetic Impact	Security Level
Chemical / Structural Bonded (Maximum Safety)	The panel is applied using high-performance polyurethane and elastomeric adhesives to metal profiles. Continuous hold across the entire height of the panel.	Completamente nascosto, superficie pulita, planare e continua.	Maximum safety. Uniform load distribution (wind and expansion). Certified durability of over 25 years*. In the event of breakage, it retains 100% of the fragments at the desired height.
Visible Mechanical with Chemical Support	Integration of exposed stainless steel hooks combined with structural bottom gluing.	The hooks are visible along the joints and can be painted to match the slab.	Redundant. Combines the continuous stability of the glue with the visual safety of the hook. Used for high ceilings or as specifically required by the building management.
Retractable Mechanical (KERF System)	Micrometric incision in the thickness of the edge of the ceramic slab into which the aluminium fixing profile is inserted.	Completely hidden. The facade surface remains clean and free of visual interruptions.	Excellent. Requires adequate sheet thicknesses and precise industrial processing.
Retractable Mechanical with Rear Bolts	Insertion of special geometric expansion plugs on the back of the slab, pre-assembled in the workshop.	Completely hidden. Maximum freedom of expression for exceptionally large modules.	High level of static constraint, ideal for absorbing deformations and dynamic movements of the building.

System Certification and Technical Management

Handling of the 300 x 100 cm h slab

Risk prevention is not limited to the choice of hook, but also involves comprehensive structural calculations. The methodological process applied by VM Group includes:

1. Wall support verification: Pull-out test to verify the anchors' tightness on the existing infill.

2. Customized static calculation: Sizing of aluminum uprights and crosspieces based on the actual wind pressures of the specific climate zone.

3. Rear safety net: Application of a fiberglass mesh on the back of the ceramic panels (fiber reinforcement) to prevent them from tipping over and falling in the event of a violent external impact.

Conclusions

Building envelope engineering is the only true guarantee for protecting capital investments and public safety. When choosing large-format panels for a ventilated façade, the technical partner's experience in managing tolerances, expansion joints, and structural anchoring systems makes the difference between a long-lasting project and a potential technical risk.

VM Group offers designers, companies, and general contractors its in-house engineering office to support the development of the executive project from the early visual concept stages.

*You can download the full official text directly from the EOTA server:

EOTA - European Assessment Document EAD 090097-00-0404

Evidence of Durability (Working Life)

In the document, in the Working Life/Durability section (section 1.2.2), the following is explicitly stated:

The assessment methods included or referred to in this EAD were written based on the manufacturer's request to consider a working life of adhesive systems or bonding kits for their intended use of at least 25 years, provided they are subject to appropriate installation and maintenance.

All accelerated aging tests performed by notified laboratories (thermal shock, freeze/thaw cycles, water immersion, and resistance to the combined action of humidity and atmospheric agents) are calibrated and structured following this regulatory framework to ensure that the structural integrity of the chemical fastener does not decline below safety limits over a quarter of a century.