This paper examines housing affordability in Ireland by looking at the distribution of housing costs across households. Using microdata from the SILC survey over the period 2005-2015, the contribution of this paper is threefold. First, the paper considers the trends in the cost of housing in Ireland across groups of households split by age, region, household structure, and their position in the income distribution. Second, we apply selected international housing affordability definitions and explore the share, and composition, of households in Ireland that would be captured by these definitions. We do not find evidence of universal affordability difficulties in the Irish market. However, certain groups do face acute affordability challenges. Third, working towards a definition of housing cost affordability for use in Irish policy discussions, we provide some guidance as to what such a definition could look like.