Introduction The 28 February 2019 decision as to liability for the Lacrosse Tower fires of November 2014 will send shockwaves through the construction industry.[1] The fire was caused by a discarded cigarette butt that ultimately ignited Aluminium Composite Panelling (“ACP”) on the façade of the 21 storey apartment block. The industry has been waiting with baited breath to find out who might be liable for the $12.7 million cost to compensate the building owners for repair of the fire damage and replacement of the cladding with an alternative product. The ACP used in the Lacrosse Tower was constructed with two layers of 0.5mm thick aluminium sheeting between which was sandwiched a core layer of about 4mm in thickness of 100% polyethylene. The material is strong, light weight, easily bent to a shape and offers long term aesthetic appeal. In the last two decades its use in Australia has become widespread, including on the facades of hundreds of high-rise apartment blocks. Across the world there have been dozens of fires similar to the Lacrosse fire, some resulting in fatalities. The evidence in the Lacrosse case showed that ACP, when subjected to significant heat by way of a fire, delaminates. The delamination exposes the interior polyethylene layer to flame and oxygen. Some have described the polyethylene layer as “frozen petrol”. The polyethylene then liquifies resulting in an extremely rapid escalation of fire. The Proceedings The owners of Lacrosse sued the builder for $12.7 million, essentially for constructing an unsafe building, constructed with ACP cladding. The builder denied liability but said that, if it was at fault, the fire engineer, the architect and the building certifier (“the Professionals”) should reimburse it for its liability. The builder said it had relied upon their professional expertise when it incorporated ACP cladding into the design and construction of Lacrosse. The Building Code As with all buildings in Australia, Lacrosse was required to comply with the BCA[2] applicable at the time of its construction. Compliance with the BCA can be achieved by two paths; strict compliance, known as deemed to satisfy compliance, (“DTS”) or alternatively, a performance-based compliance. Where a performance-based solution is adopted, an assessment is made as to whether, notwithstanding the literal non-compliance of the method or product, the performance of the building is safe if the method or product is adopted. In the Lacrosse project, the use of ACP was said to be a DTS solution. Hence, it was necessary that it complied, in every respect, with the literal requirements of the BCA. The BCA required the cladding of Lacrosse to be “non-combustible”, subject to any exclusions. In the proceedings, two exclusion clauses in the BCA were relied upon as a justification for the DTS use of ACP cladding on Lacrosse: Clause C1.12 and Clause 2.4. The Clause C1.12 exclusion Clause C1.12 of the BCA allowed for the use of combustible bonded laminated materials where— (i) each laminate is non-combustible; and (ii) each adhesive layer does not exceed 1 mm in thickness; and (iii) the total thickness of the adhesive layers does not exceed 2 mm; and (iv) the Spread-of-Flame Index and the Smoke Developed Index of the laminated material as a whole does not exceed 0 and 3 respectively.