With the vigorous development and application of the external wall thermal insulation technology, the design of the external wall thermal insulation system has gradually shifted from the early rigid anti-crack technical route to the layer-by-layer flexible anti-crack technical route. Because the thermal insulation layer is generally light in density and low in strength, and its external dimension is unstable due to the impact of temperature and humidity deformation, it is required that the matching plaster layer, putty layer and coating layer must be able to effectively adapt to this change. 

At present, There are many researches on plastering mortar, and it is also recognized that flexible polymer mortar is used as the mortar for external wall insulation, and corresponding standards have been formulated and issued to restrict it. Putty for external wall insulation, as a matching product with external insulation system, must not only meet the performance of ordinary external wall putty, but also meet the dynamic stress changes from the insulation system.