When you're looking at roofing, you might assume that there's a world of difference between the kinds you find on homes and those you see atop commercial buildings. However, this isn't quite the case. The primary factor distinguishing one roofing system from another isn't whether the building is commercial or residential, but rather the materials and methods used to accommodate the roof's pitch (or slope).
There are two main categories to consider: low slope (or "flat") roofing systems and steep slope roofing systems. Steep slope roofs, which are common in residential settings, consist of an underlayment layer with the roofing material—such as shingles—installed on top, followed by the installation of accessories and flashings. This design takes advantage of the slope, which naturally allows water to run off quickly, mitigating concerns about water pooling.
Low slope roofs, on the other hand, require a design that can handle water sitting—or "ponding"—for a while, given that it won't flow off as easily. For example, in systems using single-ply membranes like TPO or PVC, all the edges and overlaps are carefully sealed, often through welding, to prevent leaks.
Regardless of whether you have a commercial or residential building, if you were using shingles on a commercial property, the installation process would mirror that of a residential home. The essentials for both types of buildings remain constant: proper flashings, a secure underlayment, the primary roofing surface, and necessary accessories.
The story is similar for flat roofs. While you might find additional capping and metals in use, as well as specific accessories that suit the building type, the basics are largely unchanged. A two-ply system involves a base and a top layer that are welded together for a secure seal. And if you're creating an inclined surface on a flat roof to encourage drainage, you might opt for a tapered insulation (ISO) system.
In summary, the differences between residential and commercial roofing systems aren't as substantial as one might think. The focus is less on the building's use and more on choosing the right materials and methods for the roof's specific pitch and expected water flow, ensuring a durable and effective roofing system.