High-Rise Buildings with Combustible Exterior Façade Systems: A New Fire Risk Assessment Tool

Susan Lamont
Associate Director
Arup, Dubai

Fires in existing high-rise buildings involving the combustible exterior wall assemblies are becoming more prevalent in cities globally. This presentation will outline the background research and methodology developed for a new prioritisation and risk assessment tool for use by Authorities Having Jurisdiction (AHJs), building owners or facilities managers to assess existing buildings with combustible façade systems across a large portfolio of buildings.
The methodology is qualitative and takes into account the existing building envelope; potential ignition sources; building characteristics; and existing fire safety measures such as means of warning, containment, and extinguishment. It is based on a two-tiered assessment process.
Tier 1 entails an AHJ, building owner, or facility manager answering a small number of questions with clearly pre-defined answers, to inform the ranking of buildings within their portfolio. Some questions pertain to the combustibility of the insulation and facade cladding; the presence of sprinklers; potential ignition sources; and the type of alarm system.
Tier 2 is where authorities will complete a deeper fire risk assessment evaluation of those buildings deemed at risk in Tier 1. Onsite inspection; as-built information; maintenance records; samplings; and laboratory testing of unknown facade materials are considered in this section.
Based on the answers given by the user, each variable under assessment is qualitatively scored and then combined by the methodology to assess the likelihood and consequence (risk) of a fire over multiple stories of a high rise building.
The methodology is not a code compliance check and therefore can be used in any geographic area. It is suitable for use with residential (hotel, apartments) or business (office) type occupancies that are over 18m high.