In this study, fragility functions are developed to estimate expected volcanic ash damage to vinyl greenhouses and livestock sheds among common agricultural facilities in South Korea. The fragility functions are derived through the FOSM (first-order second-moment) analytical approach based on the thickness distribution of volcanic ash observed in the 1980 eruption of Mt. Saint Helens in the USA and on agricultural facility codes and specifications in South Korea. In this study, the volcanic ash fragility functions evaluated represent the conditional probability of failure of vinyl greenhouses and livestock sheds over the full range of volcanic ash loads. For the evaluation, 4 types (i.e., automated, single span, tree crop, and double span types) of multi-hazard resisting vinyl greenhouses and 3 types (i.e., standard, coastal, and mountain types) of livestock sheds conventionally utilized in South Korea are considered. All volcanic ash fragility functions estimated in this study are fitted using parameters of the lognormal CDF (cumulative distribution function), and the obtained parameters are compiled into a database for use in the future. The volcanic ash fragility functions developed in this study are intended to be used to evaluate potential risks and losses from volcanic eruptions around the Korean Peninsula.