The threshold for a 'Relevant Defect' under the Building Safety Act 2022: the First-Tier Tribunal's decision, 6 January 2026
What is and isn’t a ‘Relevant Defect’ under Section 120 of the Building Safety Act 2022 (BSA) continues to be debated amongst parties to fire-safety remediation projects, whether an external wall system or internally. The Vista Tower decision remains the most salient answer, pending the appeal to whether it was ‘just and equitable’ to make a remediation contribution order (RCO) for £13m against nearly 90 respondents. One of the central questions in that appeal is what the threshold is for a defect in a building to become a ‘relevant defect’ including whether it must cause an intolerable risk of harm or not.
In a decision released on 6 January 2026, the First Tier Tribunal (FTT) is beginning to answer these questions. The Canary Riverside estate situated on Westferry Circus in London is an extensive mixed-use residential development including a hotel. The FTT has held this month (LON/00BG/BSA/2024/0005 LON/00BG/BSB/2024/009) a ‘building safety risk’, featuring within the definition of a ‘Relevant Defect’ under s.120, refers to any risk, however small, to people's safety arising from fire spread or a building collapse.
The FTT rejected arguments that a risk must exceed a certain threshold to constitute a relevant defect, noting that the degree of risk is more relevant to determining appropriate remediation rather than whether a defect exists. It is then the task of PAS 9980 to identify whether remediation is necessary. That means identifying a relevant defect does not necessarily translate into a requirement for remediation every time because the purpose of PAS 9980 is then to assess that risk.
The Development
Canary Riverside contains 280 private residential apartments across four buildings: Belgrave Court, Berkeley Tower, Eaton House, and Hanover House. They are all ‘relevant buildings’ for the purpose of s.117 of the BSA.
There are also rental units at Circus Apartments, the Canary Riverside Plaza Hotel, health club and restaurants.
The Proceedings
The Secretary of State brought two applications for a Remediation Order (“RO”) and/or Remediation Contribution Order (“RCO”).
The Respondents were Canary Riverside Estate Management Limited, Octagon Investments Limited, Yianis Holdings Limited, and Riverside CREM 3 Limited.
Liability centred upon seven external wall systems. Each party’s appointed fire engineering expert agreed that a building safety risk existed in relation to three of them, but they disagreed on the remaining four.
The FTT ultimately held six contain relevant defects but the seventh, reconstituted stone cladding, did not.
The “Risk”
Whether or not those four disputed wall types constituted a building safety risk meant assessing expert evidence with respect to the risk of spread of fire or a structural failure. The FTT applied the reasoning expressed in Waite v Kedai that whether a defect is relevant is to be assessed at the date of the FTT hearing and whether that defect causes a building safety risk in light of today’s knowledge (as opposed to whether or not the works complied with the Building Regulations in force at the time). The FTT held:
“Compliance with building regulations at the time of construction cannot, for example, cannot be definitive, because regulations have changed over time. The better approach, in our view, is to focus on whether an asserted defect causes a building safety risk. If something was done (or not done), or if something was used (or not used) in connection with relevant works to a building, which has caused a building safety risk, it will be a relevant defect for the purposes of s.120.” [paragraphs 47 and 48].
The Respondents argued a relevant defect cannot mean any risk arising from the spread of fire or building collapse, as all buildings carry a degree of risk. It would therefore follow there must be some defects where the risk is so low it cannot amount to a Relevant Defect. The Respondents asserted the starting point to see whether a risk is sufficiently low has to be a PAS 9980 assessment, borrowing from the FTT’s decision in Vista Tower that any risk above “low” risk may be a building safety risk.
The FTT disagreed. The FTT decided any risk, no matter how small, can be considered a building safety risk. A PAS9980 assessment would be “clearly relevant” to any such assessment, but not conclusive. That is because the threshold test for tolerance “is a low one” and that the FTT’s task is to identify whether, at the date of the hearing, a risk exists (paragraph 42).
In other words, the FTT decides whether a risk exists, not the degree of that risk. Identifying the risk comes before determining the defect. This follows on from decisions in Centre Point and Hillside that the role of the FTT is to assess the evidence before it and not append detailed schedules of how works are to be carried out to remedy that risk because the FTT’s task is to answer the ‘what’, not the ‘how’.
Interestingly, the FTT considered its decision is not inconsistent with Vista Tower, but that if the Upper Tribunal were to hold a “low” risk assessment in a PAS9980 means that a defect is incapable of amounting to a building safety risk, the FTT “respectfully disagree” (paragraph 41).
Assessing the Risk
The FTT turned to numerous sources when tasked with assessing any risk, including Approved Document B (ADB) - a practical guidance on how to comply with the Building Regulations in relation to fire safety. Compliance with ADB does not necessarily guarantee compliance with the Building Regulations.
In assessing whether Relevant Defects were present at Canary Riverside, both experts emphasised compliance with ADB is important, with the Applicant submitting the following approaches could best describe the approaches one many take:
- ADB Approach: focusing on compliance with ADB, acknowledging there is wide range of acceptable design and construction solutions which may not strictly comply with ADB.
- PAS 9980 Approach: assessing in accordance with PAS 9980.
- Cautious Approach: accepting any risk above “low” under a PAS 9980 assessment may result in the FTT determining a relevant defect exists.
For those seeking widescale remediation to categorically ensure the building is made as safe as possible, the cautious approach is naturally given greater weight.
Decision
The FTT decided three of the four disputed external wall systems constituted a building safety risk due to non-compliance with ADB.
External Wall Type 1 (EWT1), a masonry cavity wall with combustible phenolic insulation, which included most of the external walls at Canary Riverside, received the greatest amount of discussion. The Applicant’s expert considered this wall type to be a building safety risk under both the ADB Approach or Cautious Approach, but not if using the PAS 9980 Approach.
The Respondents’ expert submitted evidence to show EWT1 was inherently safe, including pursuant to the PAS 9980. In particular, it was said to be “manifestly obvious to a competent fire risk assessor that the risk to life from fire spread over external walls would not warrant an FRAEW”. A PAS 9980 FRAEW recorded a “low” risk rating.
Having regard to all the evidence presented, the FTT assessed it was the degree to which there had been compliance with Building Regulations B3 and B4 that carried the greatest weight when assessing whether the wall types under consideration caused building safety risks. The FTT considered there may be other methods to demonstrate compliance other than those in ADB, and that compliance with PAS 9980 also carries significant weight.
Missing or defective cavity barriers for EWT1 were found to constitute a relevant defect in light of non-compliance with Requirements B3 and B4. This was despite the PAS 9980 FRAEW concluding that the risk posted by the missing cavity barriers was “low”.
Does that mean remediation?
The FTT considered International Fire Consultants Limited’s technical note concluding the masonry system under EWT1 did not require remediation. The FTT concluded that whether or not the cost of remedial works was justified was not relevant to the question of whether a building safety risk was present – it may however be relevant when determining the applications for an RO and/or RCO.
The FTT held if a low risk can mean a relevant defect is present, that does not mean remedial works are inevitable. That is because the FTT’s view is the purpose of PAS 9980 is to assess those risks which will inform whether such action is necessary.
Therefore, the FTT may consider it inappropriate to order remediation where the level of risk does not justify it even where a relevant defect is held to exist. For ROs and RCOs, that means orders may be rejected even where there are relevant defects.
