Attached Greenhouses Sunrooms – Custom built attached polycarbonate greenhouses, sunrooms and solariums are often a wise addition choice for the builder. The Sundance Supply approach is a Multi Wall Lexan Polycarbonate sheet covering and the Base & Cap Installation System. The sheet comes in thicknesses from 8mm to 25mm, with warranties up to 2o years. The customer provides the frame, and remaining building components, for an elegant solution. Together this approach provides a watertight, attractive and long life attached structure, often costing significantly less than a prefab kit, that still requires customization.