A method for applying render to a substrate, said method including the steps of: securing a layer of confining mesh having a three-dimensional open cellular structure to the substrate; applying a base layer of cementitious material over the confining mesh; and screening the base layer to a depth at least substantially level with an outer surface of the confining mesh. Preferably, the method includes the further step of: applying a layer of reinforcing mesh over the base layer; and applying a top coat of cementitious material over the reinforcing mesh. A cementitious plaster formulation for use in the method as defined in the method according to any one of claims 1 to 25, said formulation including: 10% to around 40% cement by weight of total dry ingredients; 50% to around 85% sand by weight of total dry ingredients; 5% to around 40% fly ash by weight of total dry ingredients; an air entraining agent and a thickener respectively combined in a ratio of from 1:1 to around 120:1 and in a combined amount of between 0.01% and around 10% by weight based on the weight of the cement; and sufficient water to provide suitable fluidity.