Despite significant progress having been made in the study of flame retardancy of cellulosic building materials, the quest to find the ideal flame retardant material still continues. This review paper explores various options to substitute halogenated flame retardants by halogen-free alternatives in green building materials. Conventional flame retardants do not chemically react with cellulosic building materials such as bamboo. Owing to this, they remain an extraneous part of the substrate and could easily leach out due to various factors leading to low efficiency of the flame-retardant action. Durability of flame retardancy can be ensured by applying an additive that would chemically react with at least one of the ingredients of the green building material so that the flame retardant would remain an inherent part of the substrate. This paper also describes the reaction mechanisms of various treatment methodologies for ensuring the efficacious actions of non-halogenated flame retardants in green building materials such as wood and bamboo.