High moisture in the slab and associated moisture vapor transmission is one of the leading causes of resinous flooring issues and failures. LATICRETE® recommends for protection against moisture vapor or when the relative humidity (RH) in the concrete measures 75% or greater to use LATICRETE Moisture Vapor Barrier as your base coat (primer) in all epoxy systems. Read MoreHigh moisture in the slab and associated moisture vapor transmission is one of the leading causes of resinous flooring issues and failures. LATICRETE® recommends for protection against moisture vapor or when the relative humidity (RH) in the concrete measures 75% or greater to use LATICRETE Moisture Vapor Barrier as your base coat (primer) in all epoxy systems. Read Less