The introduction of the Building Safety Act 2022 represents a fundamental shift in how high-risk buildings are designed, constructed, and managed in the UK. With the rollout of Gateway 2, a key checkpoint within the new regulatory regime, specifiers, designers, and contractors must now engage with compliance in more structured and transparent ways. One of the areas most impacted by this change is through-wall construction.
Gateway 2: A New Compliance Milestone
Gateway 2, which came into force in October 2023, acts as a planning threshold at the pre-construction phase for higher-risk buildings (HRBs). Before any building work begins, full design details must be submitted to the Building Safety Regulator (BSR) for approval. This includes all aspects of the external wall system with no exceptions.
For through-wall systems, which serve as the backbone of a façade’s fire and structural integrity, this means that the selection and specification of every layer, insulation, sheathing, cavity barriers, vapour control layers, and cladding must be proven compliant as a complete, tested assembly. Fragmented or retrospective specification practices are no longer acceptable.
Implications for Designers and Specifiers
Design teams are now required to provide evidence that the through-wall construction meets all performance requirements, including fire resistance, thermal performance, structural stability, and weather protection. Simply demonstrating the compliance of individual components is insufficient; the entire system must be verified for compatibility and performance under realistic conditions.
Additionally, specifiers must ensure that the system has appropriate third-party testing and certification. Reliance on desktop studies or assumptions of equivalence is increasingly risky under Gateway 2 scrutiny. This change places a premium on early collaboration between product manufacturers, design teams, and compliance consultants.
Raising the Standard for Safety and Accountability
Ultimately, Gateway 2 enforces a cultural shift toward accountability in construction. It requires specifiers to make design decisions that are not just compliant in theory, but also provable in practice. Through-wall systems are central to that effort, both as a safety-critical component and as a symbol of how regulatory reform is reshaping best practice.
Want to learn more? Book our CPD "Specifying Compliant Through Wall Systems Used With External Facades", where we explore the BSA and Gateway 2 as part of the seminar content.
