A binder for elastomeric wall coatings. The emulsion produces durable coatings with the excellent elongation and recovery characteristics necessary to bridge dimensionally unstable cracks, particularly at colder temperatures. This product employs chemistry that imparts excellent dirt pickup resistance and improved resistance to alkali and efflorescence resistance. In addition to elasticity and durability, coatings based on this product are permeable to water vapor, which permits moisture in the masonry substrate to escape without causing blisters.