The United Union of Roofers, Waterproofers and Allied Workers, based in Washington, D.C., has 22,000 members participating in nine regional district councils across the country. The union represents members who apply all types of roofing and waterproofing systems, including but not limited to: all low-sloped roofing systems (vegetative and solar photovoltaic roofs), structural waterproofing, steep-sloped roofing systems and air barrier applications.