ISO 3957:2025 PDF

This document specifies a large-scale fire test method for measuring the heat release rate (HRR) and the smoke-production rate (SPR) of wall systems. The fire scenario covered in this document is representative of severe fires originating in near wall or corner locations of an exterior or interior wall construction. A severe fire scenario is defined that imparts a heat flux on the order of 100 kW/m2 to the wall systems. These include exterior fire scenarios such as dumpster, balcony storage fires, and vehicle fires originating outside buildings. Fires caused by combustible storage inside unsprinklered or inadequately sprinklered occupancies, such as warehouse and manufacturing occupancies, represent a few examples of severe interior fires. This document measures the HRR and SPR in accordance with ISO 24473. This document also provides guidelines for heat release and smoke production performance limits, developed and used for risk evaluation by the insurance industry. The test method is not applicable to scenarios where a fire initiates within an air cavity, if present, of an exterior wall system. The test method does not incorporate a window structure and is therefore not applicable to fire spread hazards resulting from inadequately protected window openings in a post-flashover fire scenario.