In an embodiment, a method includes applying a liquid plural component polymer to a sloped roof to form a protective surface that inhibits moisture seepage to the roof sheathing. In some embodiments, the plural component polymer may be a polyurea compound having a hardening time that is less than approximately 10 minutes. In some embodiments, one or more of the components may be aerated prior to application to the roof substrate. In some embodiments, one or more polystyrene panels may be affixed to the sloped roof prior to application of the liquid plural component polymer. Other embodiments are described and claimed.