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Rooftop Gardens and the Building Safety Act: Not a Storey, Says UK Government

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The UK government has recently clarified that roof gardens should not count as an extra storey under the Building Safety Act 2022. This update reverses a feared implication of a First-tier Tribunal (FTT) decision and re-affirms official guidance on how to measure building height. It has significant consequences for high-rise design, planning and compliance. This blog explains the legal and planning background, what the Building Safety Act and its regulations say about storeys and higher-risk buildings (HRBs), and how this clarification affects architects, developers, planners and compliance teams. We also look at real UK examples of rooftop gardens, and how encouraging green roofs aligns with sustainability and biodiversity goals. Finally, we summarise expert commentary on the ruling.



Background: Building Safety Act and Planning Context

In the wake of the Grenfell Tower disaster, the UK introduced the Building Safety Act 2022 to tighten fire and structural safety, especially for tall residential buildings. Under the Act (section 65), a higher-risk building (HRB) in England is one that: (a) has at least two residential units, and (b) is 18 metres or more tall or has seven or more storeys. Any building meeting these criteria (or qualifying under transitional provisions) must be registered with the Building Safety Regulator (BSR), appoint a Principal Accountable Person, and follow the new HRB regime (golden thread, building control by the BSR, etc).



Importantly, “storeys” are counted according to detailed criteria. The Building Safety (Descriptions and Supplementary Provisions) Regulations 2023 list certain levels that do not count as storeys – notably rooftop plant or machinery floors and basements. Other intermediate or mezzanine floors count only if they cover at least 50% of the area of the storey above or below. However, the regulations do not explicitly define a “storey” in general terms. Instead, government guidance has been used to clarify how to measure height and storeys for HRBs. In practice, this means the top floor is normally a storey only if it is an occupied, fully enclosed space, and roofs or roof terraces have generally been excluded.



On the planning side, higher buildings (above 18m or 7 storeys) require early engagement with the Building Safety Regulator through “Gateway One” applications, so planners must consider the HRB status of new schemes. At the same time, national and local planning policies strongly promote roof planting. For example, the London Plan and the National Planning Policy Framework encourage green roofs and urban greening to improve sustainability and biodiversity. A ruling that counted roof gardens as an extra floor could have undermined those planning goals.


The Controversy: Tribunal Decision vs Official Guidance

Before the recent clarification, there was uncertainty over whether a roof garden could trigger the HRB height or storey threshold. In June 2023, official guidance on higher-risk buildings stated that “a storey must be fully enclosed to be considered a storey. The roof of a building should not be counted as a storey. Open rooftops such as rooftop gardens are not considered storeys”. In other words, under the guidance a rooftop terrace was treated as part of the roof, not an occupiable storey, when measuring height or counting levels.



However, in July 2024 the First-tier Tribunal (Property Chamber) delivered a controversial ruling (the Smoke House & Curing House case). The tribunal found that an open rooftop garden on an East London block of flats effectively added a seventh storey and pushed the building over the HRB height and storey thresholds. The judge reasoned that the legislation and regulations did not expressly exclude roof gardens as storeys, and therefore it treated the roof garden as a storey. This meant the building should have been registered as a higher-risk building with associated safety obligations. The decision highlighted a conflict between the legislation/regulations (which were silent on roof gardens) and the guidance (which excluded them).



The tribunal’s interpretation created immediate confusion. Projects planning roof gardens were suddenly unsure if that design element would inadvertently make their building an HRB. The tribunal itself noted it had no jurisdiction to definitively determine HRB status, and its decision is not legally binding beyond that case. But the potential impact was real: developments skirting the 18m/7-storey line could face a new costly compliance regime purely because of a garden on the roof.


Government Response and Clarification

Reacting to the controversy, the government moved swiftly to reaffirm the original guidance. In October 2024 a joint note from MHCLG (now DLUHC) and the Building Safety Regulator instructed the industry and regulators to continue using existing guidance. It said explicitly that until changed, rooftop gardens should not be counted as storeys in determining HRB.



In May 2025 the position was made even clearer. The Ministry of Housing, Communities & Local Government (MHCLG) formally responded to the Tribunal. On 28 May 2025 it announced it is consulting on amending the HRB regulations to explicitly state that roof gardens are not storeys. Until that regulatory amendment is in place, the department confirmed that its view remains: “roof gardens are not storeys for these purposes.”  The official Building Safety Regulator news page similarly emphasises that its inspectors will continue to follow the standing guidance, noting that “rooftop gardens are not considered storeys and should not be counted as such” when deciding HRB status.



In short, the UK government has now clearly put its weight behind the interpretation that open roof terraces are roofs, not additional floors. This restores certainty to the regime: design teams can proceed knowing a green roof will not inadvertently create a 7th storey for safety purposes. At the same time, the proposed regulatory change will put this on a statutory footing, removing any lingering doubt about the legal definition of a storey.


Implications for Industry Stakeholders

This clarification has important implications for the construction industry:

  • Architects and Designers – Rooftop gardens and terraces are popular design features for amenity, climate resilience and aesthetics. Designers can now plan green roofs on towers without fearing that the act of adding a garden would breach the 18m/7-storey threshold. This gives greater freedom to use rooftop space (for gardens, sky lounges, solar panels etc.) as true outdoor space, aligning design with sustainability goals. It also means that design strategies relying on partial fourth-mechanicals storeys (e.g. plant rooms on the roof) remain safely treated as non-storeys under HRB rules. In effect, any fully enclosed residential floor counts, but an open deck or green roof does not.


  • Developers and Owners – Registering a building as an HRB means significant extra costs (building safety case reports, fees, appointing Principal and other Accountable Persons, complying with new rules for evacuation, etc). For marginal schemes, counting a roof garden as a storey could have pushed projects into this regime. The government’s stance avoids these unplanned costs for many developments. Developers should still be vigilant on height (especially if any plant rooms are included), but now know that committing to sustainable roof landscaping won’t unexpectedly trigger the higher-risk regime. This clarity can improve investment confidence: green roofs will no longer be a potential liability under building safety law.


  • Local Planning Authorities and Planners – Planners often encourage roof gardens under policies on urban greening and biodiversity. With the safety regime aligned, planners can continue to require or incentivise rooftop planting without worrying it will create extra regulatory burden. The planning gateway process itself will still involve the BSR, but the outcome will be more predictable. Early assessments can note that roof decks are excluded. Moreover, this supports the policy objective of using brownfield roof space for green infrastructure – a solution that planning policy (e.g. net zero targets, the Urban Greening Factor, and biodiversity net gain requirements) increasingly demands.


  • Building Control and Compliance Teams – Compliance officers and building controllers rely on clear rules. The government’s note ensures that inspection and approval processes remain consistent. The RIBA/BGSA guidance on measuring building height continues to apply. For buildings under construction or renovation, when calculating final height and storey count, officials will ignore rooftop gardens as before. Any pending or future higher-risk building registration will similarly count storeys per the standing guidance. Compliance teams must still document floor counts carefully (noting where mezzanines or sloped ground-floor heights apply), but the rule on open roofs is now reconfirmed. It avoids a potential compliance quagmire where a design change (adding a green roof partway through construction) might have triggered retroactive HRB status.


Key Takeaway: Practitioners should design and certify buildings per the existing government criteria: only fully enclosed floors count as storeys. When in doubt, follow official guidance and await formal regulations, rather than the Tribunal’s narrow view.


Sustainable Design and Urban Biodiversity

Encouraging rooftop gardens aligns with broader sustainability goals. Green roofs help cities adapt to climate change by absorbing rainwater (reducing drainage loads), cooling building and urban air (mitigating the heat island effect), and providing habitat for birds, pollinators and other wildlife. They can deliver biodiversity net gain, a planning requirement for new developments in England, by creating priority habitats where little ground-level green space exists. Plants on roofs also improve building insulation and air quality.



From an energy and carbon perspective, combining solar panels with greenery can offset energy use while capturing carbon. Rooftop farming or community gardens can even supply local food. For example, the IKEA Greenwich roof produces vegetables for its cafe and local charities. Social benefits include creating communal spaces and mental health value for residents. Planning policies like the London Plan’s Urban Greening Factor explicitly reward developments that include roof planting.



By explicitly stating that these sustainable features do not bump a building into the HRB regime, the new guidance removes a potential barrier to green infrastructure. Architects and city planners can factor extensive planting into designs without fearing it will add burdensome safety requirements. In practice, a building’s height is still measured to the top floor slab of the highest occupiable storey – but any external garden or terrace above that slab is treated as ornamental roofscape. This means developers retain a simple “height to the floor level” check, regardless of roof use.


Conclusion

In summary, the UK government’s recent clarification confirms that rooftop gardens do not add to a building’s storey count under the Building Safety Act. This holds true until and unless the law is formally changed – something that is already being consulted on. For the construction industry, this means certainty that green roofs and open terraces will continue to be treated as roofs, not additional floors. Architects can confidently incorporate rooftop landscaping, planners can encourage it as part of sustainability strategies, and developers can avoid unintended compliance costs.



By removing this ambiguity, the ruling supports both safety and sustainability objectives. It ensures that the strict new safety regime for tall housing applies only to the intended building form, while allowing cities to embrace the environmental benefits of green roofs. In practice, teams should follow the official guidance on counting storeys (fully enclosed levels only) and look out for the forthcoming regulations for the definitive rule. Overall, the clarification is a boon for urban design – it means amenity, biodiversity and resilience can go on rooftop menus, not just on legal charts of compliance.


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