The cementitious plaster applied to the facades of most buildings on upper campus of the University of Cape Town (UCT) has frequently been observed to fail with re-applications indicating repeated and ongoing failure. The UCT Plaster (or University Plaster, Lutyens Plaster) specification is a unique dash-finished plaster applied to many of the university’s buildings, some dating back to the 1920s, giving the plaster heritage significance. The observed failure is predominantly related to friability, delamination and spalling. Complementing this failure, there is a high variation in the plaster’s performance, appearance, and composition across buildings on campus. Investigations have shown the plaster specification to be outdated, with specific problems relating to detrimental old-fashioned colouring techniques and a lack of consideration for building materials available nowadays. Additional problems identified relate to substandard plastering workmanship and a lack of standardization. Repeating failure of the plaster results in negative social, environmental, reputational, and economic impacts for UCT. Therefore, a new specification is required, mitigating these failures and promoting standardization within heritage requirements concerning colour and texture of the plaster. Performance requirements were established in terms of fresh plaster workability, friability, bond strength, colour, and texture. A lab investigation included mix optimization and testing of workability, abrasion resistance, and bond strength, as well as visual aesthetic comparison tests. Tests were conducted on mixes with varying contents of cement, hydrated lime, sand, bonding admixture, and air entrainer. The findings show that, out of the mixes developed, a standard plastering mix and a separate finish coat mix using commercial pigments performed the best in context, provided adequate workmanship was applied.