Shown here are three fractured membrane examples taken from a fully adhered PVC membrane system less than 5-years old by a PVC manufacturer who admitted to having quality control problems over a 5-7 year period during the mid to late 1990's.
Photos # 1 & # 2 show the top and bottom view of a typical "crescent shaped" membrane fracture. The crescent type fractures appear over and around the edges of insulation stress plates and over membrane seam welds. The fracture did not go completely through the roof membrane. Many of the "crescent" shaped fractures on this roof did go completely through the roof membrane polymer from the top to bottom. Crescent fractures can be mistaken for cuts in the PVC roof membrane. The best method to identify these types of defective factures is when you the top and bottom of the roof membrane have matching fracture patterns and the polyester reinforcement scrim in the middle of the membrane remains intact.
A mechanical cut or a puncture will cut through both the membrane and reinforcement scrim.
Photo 1 Membrane Top Surface
Photo 2 Membrane Bottom Surface
Photos #3 and #4 are examples of the "star" type fracture. Star fractures were found in the general membrane field area and over insulation plates. The "star" fracture example shown is completely through both membrane polymer layers( photo #4). Star type fractures may be mistaken for hail or other impact damage. No impact depressions were found on the top surface facer of the roof insulation. The polyester scrim, in-between the top and bottom membrane ply layers is still intact and not damaged or cut. With 100's of the star shaped fractures over a large roof area ruled out mechanical damage. Checking with the US Weather Center, no record of severe hail was recorded on-site since the roof was installed, so hail damage was not a factor.
A fully adhered roof system might not leak unless the fracture is over an insulation seam. The insulation facer and adhesive under the membrane can slow or stop the leak process. Organic and inorganic mixed insulation facers were common when this roof was installed. Roof leaks increases the risk of the mold infecting the insulation, depending on local climate conditions and the number of roof leaks.
Photo 3 Membrane Top Surface
Photo 4 Membrane Bottom Surface
(Photo # 5) The small "star" fracture is shown on the upper membrane surface. Photo #6 reveals the underside of the fracture with the insulation peeled away from the bottom membrane surface. The insulation facer in contact with the membrane is turned up. The tan/brown materials on the insulation facer was in contact with the membrane under side. The tan/brown material is a combination of dirt and organic materials accumulated from the membrane fracture leaking. You can see the same materials adhered to the membrane's lower surface.
Photo 5 Membrane Top Surface
Photo 6 Membrane Bottom Surface with Insulation Facer
These fractures start developing within a 4 to 8 years period after the PVC roof system is installed. The PVC roof often begins with a small number of fractures of the type shown in these photos. The membrane fractures may leak during heavy rainfall or during slow snow melts and in ponded areas. The fractures continue to increase in number from a few fractures to hundreds of fractures in a few short years as the membrane prematurely ages. In the case of this roof, the first year the fractures were observed, it assumed the fractures were caused by mechanical damage or foot traffic and repaired. However the next year, at the roof's annual inspection, a larger number of fractures were discovered. These fracture were repaired and the next year there were even more fractures and the area involved increased, at which time the roof was tested and discovered the relatively young roof had lost a high percentage of plasticizers. The time line can vary due to climatic and local roof conditions.
The manufacturer said the basic PVC formulation during this time period performed. However the the problem age/stress fracturing shown here is the result of ineffective and poor production controls during the manufacturing process which introduced wide variations in membrane plasticizer content and key performance compounds and seemed to occur at random times. Poor post QA product testing was a contributing factor as the company did not test all membrane production runs.
During this study on other roofs, we found roofs with all membrane rolls affected with a small number of fractures and stiff membrane. While other roofs had a mixture of both good and bad PVC with some rolls with no fractures and other rolls covered with fractures.
The PVC membrane may show signs of shrinkage with the membrane taut between fastener attachment points on mechanically fastened systems. Perimeter sheets have shrunk and pulled away from wall flashings and can be above the roof substrate surface under tension. The PVC membrane may become less flexible as it ages and will feel stiff and brittle in cold temperatures. The membrane scrim becomes more pronounced as the membrane becomes thinner due to faster plasticizer losses as seen in Photo # 1.
On several roofs we observed, the owner started patching the fractures thinking the fractures was caused by mechanical damage. Not until the roofs became covered with hundreds of patches over a period several years did the owner realize they had a material performance problem. The owner’s roof asset program with annual roof inspections was key to finding the problem. One roof was 8-years old when the fractures were discovered with only two years left on the warranty.
The membrane manufacturer responded to these material problems and provided either product replacement and installation or coated the roofs with an elastomeric roof coating at no cost to the owner, once the building owners or roofing contractors discovered the fractures and reported them. The membrane fracture examples shown in these photos were manufactured over a time span covering 5 or 6 years ending mid 2000. Once the production control problems and testing were discovered and identified. The roof sytem manufacturer changed their manufacturing process and quality control. Today we know of no similar problems with the manufacture's current roofing products.
If your PVC roofs installed from 1995 to mid 2000 and begins to develop the type fractures shown in these photos, please contact Corporate Roof Consultants. CRC can test and identify the roofing membrane to determine what is causing the fractures and help you secure a valid warranty claim if the PVC membrane is defective. Fractures on any manufacturer's roofing products does not mean the resulting fractures are caused by defective materials. Foot traffic, hail damage, wind blown objects and equipment servicing can be the fracture source. CRC does not automatically assume the problem is due to manufacturing or formulation.
It is important all leaks and fractures be reported to the roof material manufacturer within the time frame outlined in your roof warranty to keep your current warranty valid.
PVC roofing is one of the best single-ply membranes and has a long history of excellent performance. CRC has observed 20-years old PVC roofs and they are still performing well and still in service. Compared to many roofing products, PVC is contractor friendly both in quality and ease of application. Properly formulated and manufactured PVC and other roofing materials give years of good service. Other membranes such as TPO, especially 45-mil while and early black TPO membranes, EPDM, Hypalon, and modified bitumen systems have seen problems with formulation, sub-components and manufacturing. The key is identifying the problem and making a warranty claim prior to warranty expiration.