Sourced from FacilitiesNet
One evolution in roof design mentioned by both representatives of the roofing materials manufacturers are the challenges to the roof system from using the roof in ways besides waterproofing. As Miranda puts it, “We are expecting roofing systems to do more than they can. We want them to be more than a roof.” As available land shrinks, any real estate in the building is seen as a money loser if it cannot be utilized for something. So now roofs are being used as recreational surfaces, platforms for holding solar panels and integrated PV systems, planting and garden areas, plaza decks, and cell phone towers.
Each of these uses creates its own challenges to the design of the roof and adds new complexity to the system as a whole. In the case of garden roofs (also known as green or vegetated roofs) a whole new set of issues arise. The membranes must be protected from the plant root systems’ ability to penetrate membranes in their search for water. The weight of the plants, planting medium, any water in the system, and any hardscaping for walkways must be accounted for in the design of the structural system. Access to the membrane for maintenance and repair needs to be considered. Irrigation of the plants and access to the plants for maintenance and replacement also must be considered. Access to public areas must be provided for people with disabilities. All these factors require expertise in landscaping, mechanical systems and structural engineering to design such a roof system. Except for the plant-related issues, plaza deck design requires the same considerations as the vegetated roofs.