Organic mastics are divided into two categories. “Type I” describes the most water-resistant mastics. These may be used in commercial and light-construction applications where there is some limited water exposure. Type I products also may be used for residential floors and countertops.
“Type II” mastics are restricted in terms of recommended use, because they do not have as high a level of water resistance as Type I products possess. Type II mastics may be used only for walls and ceilings in light-construction applications that are dry or subject to minimal water exposure.