Gallaher Companies is a development company headquartered in Windsor, Ca with projects throughout the Western United States. ... Founded and run by the Gallaher Family, the company manages all aspects of the development process. From site acquisition, entitlements, architectural and landscape plans, to floorplans and interior design: all is handled in-house. The final phase, building, is realized by the building arm, OSL Construction. With all aspects under the same roof, the company moves swiftly and efficiently with optimal quality control, from beginning to end. read more