Single-ply roofing membranes are the fastest growing new and re-roofing products in the industry. Insurance carriers and law firms are faced with hail damage claims every day and need forensic engineers and structural/building materials experts to assess the facts. So here is a quick overview of what hail damage looks like in two of the most common types of single-ply roofing membranes:

What is Single-ply roofing membrane material?

There are two main types of single-ply roofing membrane material, plastic and rubber. ‘Thermoplastic’ and ‘thermoset’ are terms used to categorize much smaller sub-groups of specific membrane types by the materials and manufacturing process. Common thermoplastic products are thermoplastic polyolefin (TPO) and polyvinyl chloride (PVC). A common type of thermoset membrane is EPDM, which stands for Ethylene Paropylene Diene Monomer.  

How do you recognize hail damage to roofing membranes?  

There are visually distinct damage characteristics in the various materials. Impact testing which correlates with hailstones indicate a concentric, circular fracture pattern or star-shaped fracture within the top ply of TPO and PVC membrane. EPDM damage is evidenced by indentations within the underlying insulation boards and small discrete tears within the membrane. While visual inspection can be performed as a start, EPDM fractures can be difficult to see with the naked eye.

Need to know more about hail damage and forensic inspections of roofing materials?

Read the full article, take the quiz and contact VERTEX. Also, watch for part II of this series in PLRB.

PLRB – Hail Damage to Thermoset and Thermoplastic Roofing Membranes from The Vertex Companies, Inc.


Kevin Maxwell, PE, PMP

Assistant Vice President, Forensic Engineering Manager