May 29, 2019

Different types of Flat Roofs

One of the reasons flat roofs are so popular is that they are an economical roofing option for homes and industrial buildings. Flat roofs also provide usable space to install solar panels, rooftop air conditioning units or verdant rooftop gardens. However, before hiring an experienced flat roof repair and maintenance company, it’s important that you consider which type of flat roof will be best for your home or business.

Below, you’ll find information on different types of flat roofs. This will help you evaluate the pros and cons of each flat roofing material so that you can make an informed decision.


PVC roofing membranes are constructed from a continuous filament lattice called a scrim which is laminated with UV resistant PVC thermoplastic. PVC membranes are a modern and very effective roofing material for many reasons:

PVC is inherently flame resistant. PVC membranes will not sustain a flame when the fire source is removed. High flame resistance can make it easier for PVC roofing systems to attain Class-A fire ratings than for other roofing systems. Combustion, especially incomplete combustion, is a source of many environmental toxins. A roof membrane that does not burn is less likely than a flammable roofing material to emit potentially harmful substances.

PVC membranes are flexible. Most PVC membranes are very flexible and can be easily customized to accommodate rooftop variances. Superior Services RSH Inc.’s PVC roofing systems are custom-made (prefabricated) to fit each building. Customization can reduce the potential for scrap and waste at the job site.

PVC membranes are lighter in weight than other roofing systems. PVC roof membranes typically add very little weight to an existing structure. In a re-roof situation, a PVC roof can often go directly over the existing system. This avoids costly tear-offs, meaning no asphalts, felts or other old roof materials go into landfills.

PVC membranes are heat-weldable which creates strong and reliable seams. Reducing the potential for leaks to occur also reduces the possibility for interior dampness and subsequent mold to develop. Some PVC membranes use two-way venting, which allows the roofing system to “breathe” and can reduce the potential for trapped moisture.

PVC membrane roofs can be highly reflective. PVC roof membranes are typically designed to be highly reflective, keeping buildings cooler, reducing energy demand, and helping mitigate urban heat island effects.

PVC is highly-resistant to most chemicals. PVC membranes provide long-term service in the harsh environments experienced on rooftops. Many PVC roofs are still functioning after more than 30 years of service. A longer-lasting roof means less frequent roof replacements over the life of a building. A building lasting 100 years may go through eight to ten non-PVC roof systems, but only three to four PVC roofs.

PVC is easily recycled. During the production of some PVC roofing systems, there is virtually no waste because fabrication scrap is reground and re-used in the roofing system or other building components. Unlike many other roofing materials, PVC membranes can be recycled at the end of their lives on the rooftop.


Built-up roofs are comprised of hot tar and gravel and are one of the most affordable flat roof systems, but have many disadvantages. They are typically constructed of three or more layers of waterproof ply sheets which are sandwiched between layers of hot tar. These roofing layers are then ballasted by a layer of gravel or smooth river stone for stability and durability.

If you are concerned about the fire safety of your commercial building, built-up roofs can meet higher fire ratings. Gravel is a fire-retardant roofing material. However, roofs that are ballasted with rock are also very heavy, which can put extra stress on your building’s structure. This type of roof system is also particularly difficult to tear-off after its lifespan has been exhausted. This difficulty in removal adds to subsequent roof replacement costs. Built-up roofs are often not appropriate for some applications because roofing installation is messy and the molten tar gives off a strong smell of asphalt.


Modified bitumen roofs use only a single layer of adhesive roofing material, making it feasible for DIY installations. While modified bitumen was installed by using a torch in the past, there are now self-adhering options available. Modified bitumen roofs are also lighter in color which helps reflect some of the sun’s infrared energy and reduces facility HVAC costs.

One of the cons of using modified bitumen for flat roofs is that the torch-down systems can be a fire hazard. For this reason, we strongly recommend against installing torch-down modified bitumen roofs on occupied buildings. Another disadvantage to modified bitumen is that it is not as durable and resistant to foot traffic and blown debris as other flat roofing materials. It’s not uncommon for modified bitumen roofs to have tears or scuffs over time.


Rubber membrane has historically been a popular flat roofing material. A rubber roof membrane is also known as EPDM (ethylene propylene diene terpolymer). Leaks in rubber membrane roofs can be easily repaired and repair materials are low cost. Rubber membrane roofs are relatively lightweight and are more durable than older flat roof systems like BUR and Modified, but can be less durable to punctures than modern PVC membranes. EPDM membranes share with PVC the advantage of high recyclability after the useful life of the roof has been exhausted. The naturally dark color of rubber roofs makes them prone to absorbing heat and in some circumstances, may require light-colored roof coatings, which will increase the cost of installation. Often the visual appearance of the black rubber roof is cited as its biggest detraction.


TPO stands for Thermoplastic Polyolefin. TPO shares many of the positive characteristics of PVC roofing material. It is typically white in color and fabricated from polypropylene and ethyl propylene rubbers. This result is a perfectly flat, single piece of membrane. Because of the white color of the roofing material, it is very good at reflecting the sun’s heat, reducing the amount of money required to cool buildings that use it. It is very easy to install and can be either fully adhered or mechanically attached to the roof deck. It is ideal when there are odd shapes and objects on the roof, because it is extremely bendable and weldable without sacrificing durability. There is an added benefit of TPO, that it is 100% fully recyclable!


Steel or Aluminum are commonly used as roof materials today. One of the biggest selling points is metal’s longevity. When properly installed, a metal roof can far outlive the building that it is installed on. Most metal roofs are light weight, and easy to install over existing materials. They are excellent heat conductors and ideal for Northern states where winter months can last for up to 4-5 months. They are also ideal for areas of high snow and rainfall because the roof panels lock together and prevent any water or snow from entering the building. However, metal roofs are typically only viable for sloped or low-sloped roof applications and cannot be used for entirely flat roofs. The significant cost and noise of a metal roof can also be an issue, but the life expectancy of this roof material usually outweighs the negatives.


A coating roof consists of a high-quality resin-type elastic liquid that, once dry, offers superior waterproofing and some protection against wind and physical damage from falling debris based on the thickness applied. Thicknesses range from a very light coating, generally around 3 mils, to very heavy coating in excess of 40 mils. Roof coating is the cheapest option when it comes to techniques for energy and money savings. Silicone Roof Coatings offer mildew stain and mold resistance, and will not crack or become degraded under the sun. Acrylic roof coatings are highly reflective, but need to be applied at 50 degrees F or above. Roof coatings come in a variety of color options, many of which offer excellent sunlight reflection and helps reduce your carbon footprint and Urban Heat Island Effect, that is, increased environmental heat due to human intervention.

Before making a final decision, we recommend you consult with a reputable flat roofing contractor for more information. In order to make the best out of your new roof, it’s important that you have all the information you need to make the best decision for your commercial building.

If you are interested in our flat roof installation service, please feel free to call Lansing roofing contractors at (800) 843-6561.