Development of the Holistic Artificial Ageing of Glass-to-Wood Silicone-Bonded Joints in Unitised Façades

Unitised structural sealant-glazed (SSG) façades with glass bonded directly to timber frames offer enhanced sustainability and superior thermal performance compared with conventional aluminium-framed systems. Becaxuse bonded joints must provide continuous structural support to the glass throughout the façade’s service life, long-term durability is the key requirement. Standardised testing protocols are designed for glass and metal substrates, making some of them incompatible with timber substrates. To verify the mechanical suitability of the concept of direct bonding to timber, an experimental holistic artificial ageing (HAA) method suitable for the timber substrate was developed to complement standardised testing protocols. The core objective of the designed approach is to simulate realistic conditions under which façades are subjected to synergistic combinations of environmental and mechanical loads. These combined actions are integrated into a synchronous timeframe, with a 6 h ageing cycle representing each year of the façade’s 50-year service life. The HAA was conducted on specimens of the genera larch, cedar, and oak, as well as on aluminium for comparison. The impact of the ageing on the strength and stiffness of the silicone joint was assessed by uniaxial tensile tests that were conducted on both non-aged and aged specimens. Despite a slight decrease in the mechanical properties of aged specimens (3.4% in strength and 24.9% in stiffness), they remained functional and compliant with legislative requirements. The results demonstrate the suitability of this HAA method for practical use, as the testing duration (approximately 7–8 months after the start of the project) and required effort (roughly 0.4–0.5% of a medium-large project budget) can be accommodated within a project timeline. Experimental results also demonstrate that joints composed of materials used in the test may be used in practice.