Mapei Ultraplan Extreme 2 Weather Resistant Self Leveling UnderlaymentUltraplan Extreme 2 is an advanced, hydraulic cement based, self leveling compound designed for fast track underlayment applications. It is especially formulated for leveling interior, horizontal concrete surfaces where environmental controls are not operational or the building is not enclosed. Once installed, Ultraplan Extreme 2 is not affected by exposure to intermittent rain exposure after 6 hours or to freezing temperatures after 3 days of curing.