Building Safety Regime

Gateway 2 is the pre-construction approval stage under the Building Safety Act. It applies to higher-risk residential buildings and replaces the previous “deposit of full plans” under Building Control. No building work may begin until the Building Safety Regulator (BSR) has approved the full, detailed design. At this point, every aspect of the external wall, cladding, balcony and terrace system must be fully designed, specified, and evidenced as compliant with the Building Regulations.

Gateway 1 tests whether fire safety has been considered strategically in the design. Gateway 2 demands proof. Applicants must submit comprehensive design information, calculations, product data and test evidence demonstrating how compliance with each applicable regulation – especially Part B (fire safety) – will be achieved in practice. It moves from design intent to verified detail, including full product selection and interface design.

The BSR expects complete technical evidence packages covering the entire external envelope. This typically includes:

• A detailed fire strategy, incorporating balcony and façade interfaces, cavity barriers, and separation from escape routes.
• Detailed evidence of the competence of the designers working on the project, including subcontractors.
• Construction drawings at a resolution that allows for installation oversight – often full GA, section and junction details.
• Product specifications, including Declaration of Performance, classification reports (EN 13501-1/A2 s1 d0 or A1 where applicable), and third-party test certificates. Structural stability is just as important as fire safety, both need to be fully evidenced.
• Installation method statements and fixings data.
• Compliance matrices showing how each regulation is satisfied.

All documents form part of the “golden thread” that continues into Gateway 3.

The Building Safety Regulator, supported by multi-disciplinary teams of fire engineers, structural specialists and building control professionals, undertakes a technical review. The applicant must demonstrate that competent persons have prepared the design, that responsibilities are clearly allocated, and that all high-risk building work (HRBW) elements, including external wall systems, meet the required standards.

Full system definition is required. Generic references such as “non-combustible decking” or “A2 cladding system” are insufficient. Each component – deck board, sub-frame, bracket, fixing, insulation, façade panel and fire-stopping element – must be identified, tested, and justified as part of a complete build-up. Interface drawings must show cavity barriers, drainage gaps, and any breaks in fire propagation paths. Where proprietary systems are used, third-party certification should match the actual configuration proposed.

Yes, but only under controlled change management. Any substitution that affects compliance – such as altering material, fixing method or junction detail – must be formally reassessed, recorded, and approved before installation. Uncontrolled substitution is one of the most common causes of delay at Gateway 3. MyDek assists project teams in assessing equivalent performance and preparing change-control documentation to maintain compliance continuity.

Change is inevitable in a project to a greater or lesser degree and at any point in the design, build or occupation stages, and management of the changes is crucial. When a change is required, the Principal Designer must make a final decision on how to handle this in one of three ways:

1. A major change where the structural and/or fire strategy of the building is impacted in some way. In this instance, the Regulator must be informed immediately, and no work is allowed to continue until approval for the change has been issued.
2. A minor change where the structural and/or fire strategy is not impacted directly, for instance, a like-for-like replacement of a product, or a superior product substitution. In this instance, the Regulator must be informed, but work can continue. Proof will be needed at Gateway 3 that the change has been adequately managed.
3. A trivial change such as an alternative colour or finish. This is a recordable change. The Regulator does not need to be immediately informed, but a record must be kept of the change and must be submitted as part of the Gateway 3 application.

In all cases, what is installed on the building must be fully reflected in the Golden Thread of information.

Comprehensive evidence is essential. For cladding and balcony systems this may include EN 13501-1 classifications for combustibility, CWCT test data for weather performance, mechanical testing to EN 1990/1993 design standards, and corrosion or durability data to BS EN ISO 9223 or similar. All test reports must relate to the same configuration and materials proposed for use on the project. The BSR will reject evidence that is outdated, incomplete, or not representative.

Interface design is critical at Gateway 2. The submission must show how balcony or terrace systems tie into the primary structure and façade without compromising fire resistance, drainage, or thermal continuity. Each junction – edge connection, soffit, balustrade, or waterproofing interface – should be fully detailed, labelled, and cross-referenced to the fire strategy. Coordination between structural, façade and fire engineers is mandatory.

Gateway 2 marks the point where the golden thread becomes an operational document set. Every drawing, test certificate and calculation must be indexed and traceable. This information will form the baseline for construction verification at Gateway 3. Managing version control, file naming, and approval status at this stage prevents non-conformances later. MyDek can help maintain structured data packages for external envelope systems.

Typical issues include incomplete design information, mismatched fire test evidence, missing third-party certifications, or poor coordination between trades. Another frequent cause is lack of clarity about load paths or fixings between balcony systems and the façade structure. Early engagement with specialist suppliers, clear definition of responsibilities, and well-organised documentation are the best defences against delay.

Once approval is received, construction may begin, but the design is effectively “locked.” Any deviations or design changes must follow the approved change-control process. Site work will then be inspected and evidenced through the golden thread records to demonstrate that the building is constructed exactly as approved. This evidence forms the basis of Gateway 3 (pre-occupation) sign-off.

Gateway 2 approval is a legal precondition to beginning construction on any higher-risk building. Starting work without BSR approval constitutes a criminal offence. The regulator can issue a Stop Notice, halting all work on site until full compliance documentation is submitted and accepted. In serious cases, directors and dutyholders may face fines or prosecution under the Building Safety Act 2022 and the Building Act 1984. The BSR also has powers to require demolition or alteration of non-compliant work. If false or incomplete information is provided, or competent-person declarations are missing, the submission will be rejected, and future approvals may be subject to enhanced scrutiny.

MyDek provides complete system documentation – technical drawings, test data, structural calculations, and declarations – to support Gateway 2 submissions. Our design team helps project engineers and fire consultants prepare compliant interface details, coordinate decking layouts, and evidence A-class performance. We also support controlled substitutions and data management to maintain the golden thread, ensuring that the project moves efficiently towards Gateway 3 approval.