The Building Safety Act and Roof Terraces: What Duty-Holder Obligations Mean in Practice
The Building Safety Act 2022 introduced a duty-holder framework that fundamentally changes who carries design-stage responsibility for decisions made above occupied space. For architects specifying roof terraces on higher-risk buildings, the implications are direct and largely unaddressed in current practice.
Balconette, the manufacturer of the BalcoDeck® non-penetrative deck and balustrade system and holder of patent GB2636232, is calling attention to the specific obligations the BSA creates for Principal Designers specifying roof terrace details - and the documentation gap that most architects have not yet closed.
The golden thread and the roof terrace fixing
The Building Safety Act requires a continuous documentary record - the golden thread - from design intent through to as-built completion and beyond. For higher-risk buildings, this record must be maintained and made available to the Building Safety Regulator throughout the building’s lifecycle.
A penetrative balustrade fixing installed by a subcontractor after the waterproofing membrane was signed off represents a break in that thread. The membrane specification is recorded. The waterproofing installation is certified. But the fixing through that membrane, made weeks or months later by a different trade, may not appear in any document that connects back to the design intent for the waterproofing system.
This is not a theoretical risk. On conventional roof terrace projects, the structural engineer specifies the balustrade fixing, the waterproofing contractor installs the membrane, and the balustrade installer introduces fixings through it at a later programme stage. There is no single document that records the interface between these three scopes, confirms that the membrane manufacturer was consulted, or provides evidence that the membrane integrity was verified after the fixings were installed.
Under the BSA, the Principal Designer carries a duty to ensure that design information is compiled, managed and handed over in a way that supports the golden thread. A fixing that compromises the waterproofing system and is not documented as part of the design record is a golden thread problem - not just a waterproofing one.
What the duty-holder framework changes
Before the BSA, an architect whose specification led to a roof terrace leak had a PI exposure that played out through the courts, often years after practical completion. The BSA does not remove that exposure - but it adds a regulatory dimension. The Principal Designer who cannot demonstrate that the golden thread was maintained for a higher-risk building above 18m is not simply at risk of a negligence claim. They are at risk of regulatory scrutiny.
The Act also changes the accountability structure at design stage. The Principal Designer is now explicitly responsible for coordinating design information across disciplines. Where a roof terrace involves structural, waterproofing and balustrade scopes that traditionally have not coordinated at the interface, the Principal Designer cannot simply issue drawings and leave the coordination to the contractor. The BSA requires that design information is coordinated before it reaches the site.
What non-penetrative certification provides
Effi Wolff, founder of Balconette and creator of the BalcoDeck® system, said: “The Building Safety Act has created a documentation requirement that penetrative balustrade systems cannot satisfy cleanly. When you have three trades - structural engineer, waterproofer and balustrade installer - each working in sequence with no single document connecting their scopes, the golden thread has a gap in it. BalcoDeck® was designed so that the structural performance and the membrane integrity are confirmed in a single Certificate of Compliance. That’s not just a product benefit - it’s a direct response to what the BSA now requires.”
The BalcoDeck® Certificate of Compliance covers structural load compliance to BS EN 1991-1-4 and BS 6180, membrane integrity confirmation, installation methodology documentation, and pre- and post-installation survey records. It provides a single document that can be incorporated into the golden thread information pack for the building.
For architects specifying roof terraces on higher-risk buildings, the question is no longer just whether the detail works at practical completion. It is whether the documentation supports the duty-holder obligations that extend from design stage through the building’s lifetime.
