Roofing Systems: What are They and How to Choose
In the construction or renovation of a commercial building, one question that always comes up among builders and contractors is “what type of roofing system should we use?” This, of course, is a valuable question, as the roof is an important part of any facility. In regards to commercial buildings, there are a variety of roofing options to choose from.
Traditional Built Up Roof
This type of roof has been around for over a hundred years; it consists of multiple plies of felt adhered in hot asphalt with gravel cast into a flood coat of asphalt on top of the system, which provides a protective barrier for the plies. The multiple plies provide redundancy within the roofing system. This type of system is now also installed with cold asphaltic-based adhesive in lieu of the hot asphalt to reduce odor during the installation process.
Modified Bitumen Roof
Similar to traditional built-up roof systems, modified bitumen roof systems provide redundancy with multiple plies installed. Unlike felt plies of traditional built up roofs, the modified bitumen material is made up of rubberized asphalt with reinforcing fabric embedded in the sheet. This provides for a thicker, more durable sheet. Granulated modified bitumen sheets also have small granules embedded on top that provides a protective layer for the membrane. Due to the durability of the modified bitumen plies, a flood coat and gravel are not necessary.
Single-ply roof systems have grown in the roofing market since the early 1980s. These are flexible sheets made up of compounded synthetic materials that are most commonly known as: EPDM, PVC, or TPO. When building these systems, the contractor typically lays the sheets down in adhesives and then heat welds or adheres the seams together where the sheets overlap. While the single-ply roof system does not have redundancy, it does feature durable membranes, which can typically be installed at lower cost than redundant roof systems.
Liquid Based Membrane
The liquid based membrane roof system is an emerging one that is beginning to gain some traction. These systems typically consist of an applied resin, an embedded fleece, and then encapsulating resin. The flexibility of the membrane allows it to accommodate the most challenging flashing details.
So how does a contractor decide which roofing system to choose for a project? That decision comes down to a number of factors. First, how is the building used? The roof of a restaurant needs to consider that grease from the kitchen exhaust may impact the roof. A manufacturing plant may have chemicals or steam impact from the roof. A strip mall and apartment building have very different uses, but they both may have a large volume of small air conditioning units on the roof. All of these impact the decision of which roofing system to use. Second, where is the building located? The region of the country, and weather conditions, can impact which roof system is most appropriate. Third, what are the existing conditions of the building? Is there a roof garden, or a current roof that will be covered? Finally, the owner’s preferences obviously come into consideration.
With any commercial building, the roofing system is an important piece of the puzzle. As you can see, there are a number of roofing systems to choose from, each dependent and more efficient with certain factors. With a roofing contractor like us, you can be assured that we will choose the right roofing system for your facility.