Traditional Single Ply Roofing On Metal Buildings Is Not a Good Idea!

When most of us think about roofing, we think of the traditional asphalt shingles that are common place throughout much of suburbia.  Some might even say that no one ever got fired for choosing a single ply asphalt roof.

Well, the story is not so simple, especially if you happen to own a metal building.  “What could go wrong with a shingle roof?” you might ask.  Well plenty as Choice Roof Contractor Group points out in the following article:

Buildings that are made for single-ply membranes will be supported by bar joists that act independently from one another. Bar joists have a built-in camber, an upward curvature of a joist to compensate for deflection due to loading conditions, to aide with creating a level surface for water flow. Whereas, a pre-fab metal building is designed for balance across the entire structure with purlins, a horizontal structural component that is attached perpendicularly to the joist to create support, that work in unison.

Creating water flow with proper direction is essential to the success of your roofing membrane and your metal structure. A ribbed metal roof will direct water rather than allow it the chance to flow where it wills. When a single-ply membrane is applied to your metal roof, water flow is altered and will then flow to the path of least resistance, the mid-span of the purlins. This creates an unbalanced weight, the potential for a roof collapse and challenges the integrity of your entire structure.

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So what might be a good alternative? Well for most steel buildings a metal alloy roof is a standard alternative as  Buildings Guide describes here:

As mentioned above the visibility of your roof may affect the finish you select. Most all steel buildings come standard with a GALVALUME® roof. A GALVALUME® roof consists of a sheet of steel with 55 percent clear Aluminum-Zinc alloy coat. This protective coat is specially designed to handle the most extreme conditions, including inclement weather such as storms, rain and snow as well as consistent exposure to heat and sun. Since the Aluminum-Zinc alloy coat is clear the silver steel underneath is visible on a GALVALUME® roof. The average GALVALUME® panel comes with a 20 year warranty.

For owners who wish to make cosmetic alterations to their buildings there are several paint options for your roof. Painted roof panels are a more expensive option but buildings with painted roofs are often aesthetically preferable as they appear more finished, and blend in better with surrounding structures. The color options will depend upon the specific supplier of your steel building but the most common options are variations of red, blue, green, gray and tan. However, be sure to ask about warranty options before deciding upon a color for your roof. While most painted panels are coated with a Silicon Polyester-based paint and include a 25 year warranty, some color options are significantly less durable and may carry as few as a five year warranty.

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For more information on the advantage of metal roofing, visit this site:

One other danger that one often needs to consider in terms of a steel building is the issue of proper insulation given that metal conducts heat quite efficiently.  This is not just an issue for the building itself, but also for the roof. The danger is that a poorly insulated roof can promote ice dams in the winter.

Foam is often used on steel buildings to properly insulate the roof and the rest of the house.  That process is illustrated in the following  video from Brandon Holdeman:

Metal buildings can be quote economical for a commercial operation.  However, special consideration needs to be paid to the roof due to the issues mentioned in this article.  Take heed and your roof should last for decades to come!