The Hélios Group is made up of the companies GEC Ile-de-France (Générale d’Etanchéité et de Couverture) and Sallandre. GEC Ile-de-France, created in 1992, is a regional specialist in the waterproofing of roof terraces, and the thermal and air-proof sealing of buildings. GEC focuses on maintenance and renovation through multi-year contracts. The clientele of GEC Ile-de-France has historically consisted of administrators of private and public real estate stocks, and local communities and para-public buildings. Sallandre, created in 1875, works via plumbing and roofing installation maintenance contracts with a clientele mainly made up of large private sector commercial buildings.