A separate design characteristic of a metal roof system is the slope. Metal roof systems can be installed in either a steep slope or low slope application. Forgetting to consider the slope can be a major source of problems for metal roof systems.
It is important to consider the slope of the roof when designing, installing and maintaining a metal roof system. The NRCA (www.nrca.net) defines a low-sloped roof system as any roof with a slope less than 3:12. All other roof systems are considered steep sloped.
Hydrostatic metal roof systems are designed to hold water until it can drain. These roof systems are capable of holding water without the roof system leaking. Typically these metal roofs are found on larger pre-engineered metal buildings. These larger structures are more costly to design with a steep sloped roof assembly. Additional hydrostatic metal roof systems can be found on residential applications. Tin and copper metal roofs can be installed with soldered flat seams in a hydrostatic system.
Hydrokinetic metal roof assemblies are designed to shed water. These systems are designed for steep slope applications. Steep sloped applications are found on residential and commercial applications where water cannot remain on the roof system. If the water is retained on the roof system it can create hydrostatic pressure forcing water into the details and creating metal roof leaks.