The roofs of buildings play an essential role in energy efficiency because a significant amount of solar radiation is absorbed by roofs in hot weather and a significant amount of heat is lost through roofs in cold weather. This paper is a systematic literature review about roofing methods for flat roofs. Ten roofing methods are reviewed in this paper. They are concrete roof, cool roof, insulated roof, roof garden, photovoltaic panels’ roof, biosolar roof, double-skin roof, roof ponds, skylight roof, and wind catcher. The review covers each roof’s main features, heat flux reductions, payback periods, and the appropriate climate for its implementation. Furthermore, the basic principles for selecting appropriate roofing methods are discussed and future studies for integrating these roofing methods are suggested. Some of these methods can eliminate the need of installing HVAC (Heating Ventilation and Air-conditioning) systems and others can achieve a high percentage of heat reduction if they are the right choice and they are implemented in the right circumstances. An incorrect selection could result in mild to severe energy penalties. The review contributes to the increasing knowledge about sustainable roofing and helps designers to increase building energy efficiency by selecting the appropriate roofing method.