The metal roofing market is larger than ever and the popularity of metal roofs continue to grow with both homeowners and building owners. But with so many different types, styles and profiles of metal roofing available today, it can be tough to figure out which metal roof is right for your next project. To get all the great benefits metal roofing has to offer, you need to 1) have the right type of metal roofing system, 2) use it in the right roofing application, and 3) it has to be installed correctly.
Types of metal roofing
One article is not sufficient to adequately describe each and every type of metal roofing panel on the market today, but we can separate metal roofing into two categories: metal roofing panels that attach using exposed fasteners and metal roofing that attaches using hidden fasteners.
Exposed fastener metal roofing
Exposed fastener means that the metal roofing panels are attached to the home or structure by driving a screw through the face of the metal and into the wood or metal substrate. The screws are sealed by a rubber washer attached at the base of the head that gets compressed when the screw is driving in. In other words, and exposed fastener type of metal roofing means that the fasteners or screws are visible or exposed. It requires approximately 70 screws to secure 1 sq of metal roofing. For this reason this type of metal roofing is great for light commercial buildings, warehouse roofs, agricultural buildings, pole barns and garages but it is not recommended for homes or buildings with finished interiors. (Read why we don't recommend exposed fastener metal on homes.)
Hidden fastener metal roofing
Hidden fasteners are screws that are not visible and that are under the metal roofing. This category of metal roofing is often referred to as standing seam. The metal roofing panel is attached to the home or structure by securing a clip that hooks over one leg of the metal panel. The next metal panel is then installed and covers over the clip making the fastener or screws "hidden".
There are two types of standing seam metal roofs: 1) snap lock standing seam and 2) mechanically seamed standing seam.
Snap lock standing seam is created by "snapping" on side of a metal roofing panel onto another so that they hook together and seam is raise. Mechanically seamed metal roofing panels are set side by side then a seamer is used to mechanically bend over the tops of the panels locking them together.
The pitch or slope of a home or structure is very important when choosing a metal roof. For roofing projects that have a slope of 3:12 or greater any roofing panel may be used. But for slopes below 3:12 only a mechanically seamed metal roofing panel will work. Both an exposed fasteners metal roof and the snap lock standing seam will leak on slopes below 3:12.
Structural or Architectural metal roofing
The type of decking or substrate that the metal roofing is to be installed over matters and should factor into your decision of what type of metal to choose. Structural metal panels can span over open purlings or struts while architectural metal roofing needs a solid deck or substrate such as plywood or OSB boards. Over spanning a metal panel can seriously compromise the way the metal roof functions and how long it will last. Choosing the correct gauge or thickness of metal roofing will ensure your metal roof performs as advertised.