Retrospective HRB Approval and Gateway 2: Regularising Completed Works and Approving What Comes Next
When Higher-Risk Building Status Is Discovered After Construction Has Started
Building work within an occupied apartment block can appear relatively straightforward until the building’s Higher-Risk Building status is identified. In this case, the client had already commenced and partly completed refurbishment works with an Approved Inspector involved, but without recognising that the building fell within the more stringent regulatory regime overseen by the Building Safety Regulator. Once that position came to light, the works were stopped and a specialist route forward was required.
The project now involves two connected but legally distinct approval processes: a retrospective regularisation application for building work already carried out without the required approval, and a prospective Gateway 2 building control approval application for work that remains to be undertaken. Our High Risk Building Hub explains the wider regulatory framework, while our High Risk Building Consultancy Services set out how we support clients facing complex HRB approval and delivery issues.
The immediate challenge is not simply to prepare two applications. The completed works, existing building conditions and proposed future design must be reviewed as one coordinated technical problem. This requires robust architectural information, evidence of Building Regulations compliance, clear dutyholder responsibilities and a practical strategy for resolving any gaps. Our Building Regulations Services and previous work Taking Over as Principal Designer on a Higher-Risk Building illustrate why structured technical leadership is essential when a project changes direction mid-process.
How an Apparently Conventional Refurbishment Became an HRB Project
The client approached Folly Architects after being instructed to stop work. Like many apartment owners and developers, they had relied on the professional team around the project and reasonably believed that the correct building control route was in place. An Approved Inspector had been involved, which added to the impression that the regulatory position had already been addressed.
However, responsibility for establishing the correct statutory route cannot be resolved simply by pointing to earlier involvement from a building control professional. Where a building satisfies the Higher-Risk Building criteria and the proposed works fall within building control, the Building Safety Regulator is the building control authority. Work requiring approval should not begin until the relevant approval has been obtained.
This creates a difficult position when the issue is discovered after construction has started. The project cannot simply continue under the original assumptions, but neither can the completed work be ignored. The design team must establish precisely what has been built, what remains incomplete, what evidence exists and whether the installed work complies with the functional requirements of the Building Regulations.
Separating the Retrospective and Prospective Approval Routes
The first workstream relates to the unauthorised work already undertaken. This requires a regularisation strategy supported by accurate as-built information, surveys, photographs, product evidence, specialist input and, where necessary, opening-up inspections. The purpose is to demonstrate whether the completed work complies and to identify any corrective measures required before retrospective approval can reasonably be sought.
The second workstream is the Gateway 2 application for the future scope. This must describe the remaining proposed work in sufficient detail to allow the Building Safety Regulator to assess compliance before construction recommences. Our article Navigating Gateway 2 in Knightsbridge explains why Gateway 2 demands coordinated design information rather than an outline package that is intended to be resolved during construction.
Although the two applications must be clearly differentiated, they cannot be developed in isolation. The retrospective work may affect compartmentation, structure, services, ventilation, fire stopping or escape provisions that also influence the proposed design. The future works must therefore start from a verified understanding of the current building, not from superseded pre-construction drawings.
Reconstructing the Evidence for Work Already Completed
Retrospective HRB work is often more demanding than designing prospectively because compliance must be evidenced after elements have been concealed or finishes completed. Drawings prepared before construction may no longer represent what was installed, while contractor records may be incomplete or inconsistent. A credible application needs to distinguish confirmed facts from assumptions and explain how each uncertainty will be tested or resolved.
Our first task is to create a reliable information baseline. This includes reviewing the original design package, Approved Inspector correspondence, site records, product data, contractor information and consultant designs. Those records are then checked against measured surveys and site inspections so that an accurate as-built architectural package can be prepared.
Where evidence is unavailable, selective opening-up may be necessary. This can include checking fire stopping, wall build-ups, structural connections, service penetrations and concealed materials. The purpose is not to create unnecessary disruption, but to obtain proportionate evidence for safety-critical matters that cannot responsibly be assumed.
Preparing the Gateway 2 Package for the Remaining Works
The prospective application must clearly define the boundary between completed, corrective and future work. This is particularly important where some construction has been paused midway through a sequence. Drawings, schedules and written strategies need to show the current condition, the proposed end state and the steps required to move safely between them.
As Principal Designer under the Building Regulations, the architectural role extends beyond producing drawings. It includes planning, managing and monitoring design work, coordinating consultant information and ensuring that the design demonstrates compliance. Our guidance on The Role of the Principal Designer explains why this responsibility is central to HRB projects where fragmented or contradictory information can undermine the submission.
The application also requires procedural documents that explain how compliance will be controlled during construction. These commonly include change control arrangements, a construction control plan, competence information, mandatory occurrence reporting procedures and a clear inspection strategy. These documents must reflect the real project rather than operating as generic templates detached from the proposed work.
Frequently asked questions
The following questions and answers summarise common queries relating to this topic.
A regularisation certificate application may provide a route for unauthorised building work already carried out, but approval is not automatic. The application must be supported by evidence demonstrating compliance, and opening-up, testing, corrective work or replacement of non-compliant elements may be required.
Work that requires Building Safety Regulator approval should not continue without the correct approval. The project team should define what has been stopped, protect the site and obtain project-specific regulatory advice before undertaking further construction or investigative work.
The completed unauthorised work and the proposed future work have different approval purposes. The retrospective application addresses what has already been built, while the Gateway 2 application seeks approval for work that has not yet been carried out. The information must be clearly separated but technically coordinated.
Not necessarily. The correct building control authority and procedure depend on the building classification, timing and project circumstances. For in-scope work to an existing Higher-Risk Building, the Building Safety Regulator is generally responsible for building control approval, subject to any applicable transitional arrangements.
The evidence will depend on the scope, but may include accurate as-built drawings, site photographs, surveys, product certification, contractor records, fire and structural information, services design, inspection findings and opening-up evidence. The package must clearly distinguish verified construction from assumptions.
Managing Risk Before Work Recommences
A stop-work instruction creates obvious programme and cost pressure, but restarting prematurely can make the regulatory position worse. The correct priority is to preserve the site, prevent further unauthorised work and establish a clear approval strategy. Contractors and consultants should understand which activities are paused, which investigative works may be required and who is authorised to issue design information.
The client must also be given a realistic view of potential outcomes. Retrospective approval is not automatic, and installed work may need to be altered or removed where compliance cannot be demonstrated. Equally, the future design may need to change once existing conditions are properly understood. Early clarity is commercially valuable because it allows corrective work, consultant appointments and programme implications to be considered before further commitments are made.
This case demonstrates why HRB status should be checked at the outset of any apartment refurbishment, even where the proposed work appears localised and an established building control route seems to exist. Our guide What Is a Higher-Risk Building? provides an initial explanation of the statutory criteria and why apparently modest internal works can still trigger enhanced regulatory requirements.
A Coordinated Route from Unauthorised Work to Compliant Completion
The value of a combined strategy is that it avoids treating the completed and proposed work as unrelated submissions. The retrospective package establishes the verified starting point. The Gateway 2 package defines the compliant route forward. Together, they provide the Building Safety Regulator with a coherent account of what happened, what exists now, what must be corrected and how the remaining work will be controlled.
For clients who discover HRB status after work has begun, the situation is serious but it can be approached methodically. The first steps are to stop affected work, preserve records, appoint a competent team and avoid making unsupported assumptions about the building. A structured technical review can then convert a confused project history into clear evidence, defined responsibilities and a credible regulatory submission.
Folly Architects is supporting this project through the retrospective and prospective approval processes, coordinating architectural, fire, structural and building services information while establishing the Principal Designer framework required for the remaining work. If you have commenced work within a Higher-Risk Building without the correct approval, early specialist advice is essential before further construction takes place.
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If you would like to discuss a project, clarify regulatory requirements, or understand how our experience may be relevant to your work, you are welcome to get in touch.
