On March 31st 2020 the UK masonry design code, BS 5628 [1-3], was withdrawn leaving BS EN 1996 (Eurocode 6) [4-7] and the associated National Annexes [8-11] as the structural masonry code for the UK. BS 5628 was the fi rst limit state design code for masonry in the world when it was introduced in 1978 and allowed effi cient use of both slender walls and low strength units. Eurocode 6 has brought together from the participating countries input from a wide spectrum of designers including those from countries where thicker masonry walls are normally used. This paper examines the effect of some of the change in the design code on the potential use of autoclaved aerated concrete and identifi es areas of the Eurocode that need further consideration and development.