The construction of inverted roofing systems is well known within the construction industry and has been practiced for several years. Inverted roofing systems provide for a quick, easy and efficient installation reducing cost in comparison to traditional built-up roofs. They also reduce the number of water impermeable membrane seams present on the roof, which lowers the probability that the roof will leak. Roof repairs and maintenance are made easier, and the lifetime of the roof is improved.
The industry standard inverted roofing systems typically comprise a roof deck, a water impermeable layer, a thermal insulating layer, a filtration layer, and a ballast top-layer. This composite roof structure can be manipulated and altered in a variety of ways in order to adjust the particular characteristics of the roof. For example, the ballast layer on the top of the system can be made of gravel, stone pavers, or even green material (such as grass/sod) in order to alter the functionality or appearance of the roof.
Although inverted roofing systems have provided for improvements in roofing construction, there remain some issues. Load associated with the inverted roof, and in particular the ballasting can force architects and designers to reinforce building structures to accommodate this load. Such design can increase building costs, time of construction and may limit design capabilities. The cost and time required for the installation of an inverted roofing system is also significant. The inverted roofing system layers can be worn down and degraded by environmental factors such as UV rays, moisture, and temperature. Green roofs, which utilize organic matter ballast, may also retain water mass in plant material/soil. This may further increase the load of the inverted roofing system that must be supported by the building structure.
Inverted roofing systems are manufactured such that most of the components of the roof are not fastened directly to the roof deck. By eliminating nearly all adhesives and fasteners the cost and time of roof installation are reduced. However there are concerns about wind uplift on the roof—the ability of strong wind to dislodge components or the entirety of the inverted roof. In order to combat these concerns, ballast layers have added mass which increased the structural strain on the building.
In some configurations, to create an effective inverted roofing system, the roof deck requires a slope of at least a 2% gradient. This necessity creates design obligations, high costs, and reduces the available uses for a roof structure.
In other configurations, to create an effective inverted roofing system the roof deck can be flat, but in these configurations the ballast top-layer requires a mass load of at least 10 pounds per square foot (lbs/sq ft). This necessity creates design obligations, high costs, and reduces the available uses for a roof structure.
Green roofing ballasts require maintenance and additional infrastructure. Such systems need water and nutrient to grow and thrive which must be provided through ongoing care or functioning infrastructure. These additional elements can be costly and may further increase the overall roof load that the building structure must then support.
Artificial green roofing ballasts, such as Astroturf, have been introduced in an attempt to reduce the additional resources associated with traditional green roofing ballast. Although such synthetic replacements may somewhat reduce the maintenance and infrastructure requirement, other green roofing benefits associated with the natural appearance of a traditional organic green roofing are reduced.
One product of recent developments within construction industry is the improvement of roofing costs. However loss of heat (or alternatively retention of heat), material, labor, and replacement costs drive up the overall costs of construction and in particular the costs of constructing a roof. Further specialized roofs such as traditional green roofs make for even greater associated costs.
Therefore there is a need for an inverted roofing system that is not subject to one or more limitations of the prior art.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.