Spotting Roof Trouble Early

Spotting Roof Trouble Early

The Pros and Cons of APP Modified Bitumen Roofing

by William Gerard

Choosing the right commercial roofing material for a low slope or flat roof on a building can be daunting. There are so many options available today including several thermoplastic varieties as well as classic bitumen roofing that it can be difficult to know what's really best for your business. One classic option is APP modified bitumen, or atactic polypropylene modified bitumen, an option that has been in use for decades. But is it right for you? Here are the pros and cons.



One reason that APP-modified bitumen has been in use for decades is that multiple layers of thickness provide real durability. Most APP-modified bitumen roofs are at least 2-ply, meaning there are at least two layers. This provides a lot of additional thickness, especially when compared to single-ply thermoplastic commercial roofing materials like PVC. The thicker the roofing layer, the more protection for the building.


If your commercial roof will experience a lot of foot traffic, APP-modified bitumen is one of the very best options available. In fact, it's designed to withstand foot traffic, unlike some thermoplastic materials that may become incredibly slippery and dangerous when wet. The additional thickness of the material plays a big part in its walkability as well.

Fire Resistance

Another selling point of APP-modified bitumen is its very high fire resistance. Choosing a material that will protect your building from disaster is vital.

Cold Weather

Another advantage of APP-modified bitumen is that it's a fantastic material for very cold weather areas. It won't crack or warp even in below-zero temperatures. That makes it ideal for commercial applications for buildings in climates with very cold winters.


Installation Danger

APP-modified bitumen is installed using a torching process. This means the installer uses a very hot propane-fueled torch in order to heat up the membrane so that it will adhere to the substrate. There are risks to this open-flame installation method that don't exist in the installation of many thermoplastic commercial roofing options. However, experienced and licensed commercial roofers will be able to do the job safely.

Standing Water

Another disadvantage of using APP-modified bitumen is that there is a potential for standing water on the roof if the roof doesn't have adequate drainage. Since APP-modified bitumen is often installed on flat or low-sloped roofs, proper drainage is absolutely essential. Without it, this material has a higher risk of standing water than some thermoplastic materials.

For more information, contact commercial roofers in your area today.


About Me

Spotting Roof Trouble Early

Do you know how to tell if you have problems with your flashing, loose shingles, or damaged tar pitch? Well, I didn't either until I experienced some of those issues on my own. One day, I realized that my roof was leaking and that I needed to find a solution fast. After contacting a professional roofing company, they were able to solve my troubles and teach me the signs of trouble. I want you to avoid the same types of hassles, which is why my blog is filled to the brim with information about roofing and home ownership. You never know, these tips could really come in handy!