Polymer–cement waterproof coatings couple the rigidity of cement and the elasticity of polymers into compositmembranes that prevent water penetration. In the system, polymer particles aggregate to form films in the cementitious matrix and hence plug up capillary pores and bridge micro- cracks].In this paper we present in depth case study of Dunlop K205—an acrylic polymer–cement coating for the Chinese market—and position the practical experience on the broader context of review of recent literature and commercial products. K205 was used to seal a high‑moisture bathroom in Santa Clara, USA. After six months, the coating was waterproof, flexible and did not delaminate even at elevated relative humidity.Compressive strengths and water absorptions are demonstrated in numerical results; polymer content is used to explain their variations in simulation. Comparison tables are provided among K205 and other products like Sika Damp Proofing Slurry, Drizoro Maxseal Flex and SinoMaco crystalline coatings. Permeability reduction formulas and bond strength formulas are derived for polymer contents. Real observations and simulation results for both of them are visualized by figures.We refer to 35 articles — mostly which are published post-2020, according Vancouver style, wherein findings are reported and emphasized the benefits of polymer– cement waterproof coatings for residents as well as proper mixing, application and concerns related to sustainability issues.