There are different types of low-slope roof membranes and it is important that you know the differences between them. Understanding the materials and differences between the various membranes makes maintenance easier and more efficient.

What Should You Know About Low-Slope Roof Membranes?

TPO

TPO roof membranes are all white and can be attached using a number of methods. They can be ballasted, mechanically attached or fully adhered although, mechanical attachment is the most frequently used method. This type of membrane has seams that are welded together to provide a mostly homogeneous membrane. TPO has become more common in the industry over the last few years because of its thermoplastic properties.

PVC

PVC membranes are similar in appearance to TPO membranes and are also thermoplastic in nature. This membrane material, however, is more pliant than TPO membranes because it is able to conform with substrate changes more readily.

EPDM

EPDM is a black synthetic rubber roof membrane. One method to install EPDM involves using large stones or concrete pavers (ballast) to cover the EPDM membrane. The ballast weight secures the above-deck roof insulation and roof membrane. When there is no ballast used, the system is mechanically adhered. You can identify this installation method by dragging your foot across the membrane and watching for wrinkles.

BUR

If a roof system is not a single-ply roof membrane, then you are likely working with a bituminous membrane. Bituminous membranes are usually built-up roof (BUR) membranes or polymer-modified bitumen membranes. They can be applied using hot-asphalt or coal tar pitch membranes. BUR membranes are most often surfaced with bitumen and gravel but can also have mineral-surfaced cap sheets or a liquid-applied roof coating.

Polymer-modified bitumen

Polymer-modified bitumen membranes have an unsurfaced base layer of polymer-modified bitumen membrane that is adhered to a substrate. The three most common application methods for polymer-modified bitumen membrane are hot-applied using asphalt, cold-applied using adhesives, or torch-applied. You can also choose to apply a protective aluminum coating over the cap sheet with this membrane type.

Once you know the differences between the available low-slope roof membranes, you can make an informed decision about what membrane works best for your needs. You can also better provide the most efficient roofing maintenance. Discuss the various roofing membrane options with your roofing professional to find out exactly what you need.

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