Fire safety engineering designs should comply with the ALARP requirement, meaning that fire safety measures should be implemented to ensure that fire risks are As Low As Reasonably Practicable (ALARP). However, previous approaches have often been contradictory or unclear, especially with respect to the concepts of risk aversion, the valuation of risk to life, the concept of disproportionality, and the need to take into account monetary benefits resulting from life safety investments. First, the As Low As Reasonably Practicable (ALARP) criterion is specified to a societal, risk-neutral, and scalar cost-benefit analysis in the field of fire safety engineering. This is done to overcome the shortcomings in current practice with respect to utilizing the ALARP criterion for Probabilistic Risk Assessment (PRA).Second, the ethical dilemma of the valuation of risk to human lives is addressed by application of the Life Quality Index (LQI), as has been suggested in the field of structural engineering through the recent ISO 2394:2015 standard. Contrary to the existing literature, the proposed interpretation for the ALARP requirement corresponds to an application of the LQI maximum societal benefit criterion. This ensures that safety resources are allocated so as to maximize the number of lives saved, and implies that the ALARP criterion results in stronger minimum requirements for life safety investments, i.e. societal lower bound investment levels.Third, the valuation of costs and benefits by the fire safety engineer is addressed by emphasizing the duty of care, and by specifying a benchmark criterion for the objective, diligent, and competent fire safety professional. This reinforces self-reflection amongst fire safety professionals, and diminishes the need for often unjustified or poorly specified disproportionality factors.Finally, the relationship between fire safety design and private actor cost-optimization considerations is discussed, and the presented concepts are illustrated using three examples. These clarify the application of the presented concepts and demonstrate how the societal ALARP requirement interacts with the (safety) preferences of private investors. The examples highlight the importance of the societal ALARP evaluation and show that this governs the safety investment when the private investor values damages low, applies a high discount rate, or takes into account indirect costs (e.g. aesthetic costs) related to the safety investment.