The present disclosure describes various building materials used in the building and construction industry, and to buildings or objects constructed therefrom, and to methods of making these building materials. The building materials comprise a polymeric material, such as sodium alginate and/or calcium alginate which confers significant flame-, fire- and heat-resistance or imperviousness to the materials. Other substances can be added to the materials to improve cross-linking and/or to produce resistance to fungal degradation. The building materials which can be produced, processed, or treated using the alginate polymers of the invention include, but are not limited to, wood products; masonry products; wall, roofing, flooring and siding products; and paint products. Further, sodium alginate in the form of a gel may be used as a firebreak to effectively stop the advance of grass fires, wildfires, and forest fires.