Metal roofing basics

Metal roof systems often are misunderstood, especially by building owners and consumers. For instance, many building owners are unaware that there actually are two types of metal panel roof systems. Also, building owners may not realize metal roof systems are not limited to steep slopes—they can be installed for low-slope applications, as well. But once a building owner chooses to install a metal roof system, he must be well-informed about the special design considerations that are unique to metal roofing.

System types

Metal roof systems traditionally are divided into two categories: architectural and structural.

Architectural metal panel roof systems typically are hydrokinetic, water-shedding systems. These systems are designed to shed water rapidly over panels' surfaces, so the panels' seams are not necessarily watertight. For panels to shed water quickly, a roof must have adequate slope. NRCA recommends a roof slope of 3-in-12 (14 degrees) or greater for architectural metal panel systems.