SOLUTIONS TO Insulation Facer Delamination ISSUES By John Geary elamination of facers—primarily on adhered, singleply Droofing systems interfaced with polyisocyanurate insulation—affects only a small number of jobs. Those who have been involved with such an occurrence know the repair of this situation can be very expensive. As a roof consultant, it is prudent to ask, “Is there anything that could have been done to prevent this situation, and what can be done to protect my clients in the future?” At Firestone Building Products, the Technology Department has been asking these questions as well. A review of common characteristics of delamination of fullyadhered membranes to polyisocyanurate insulation shows that rooftop traffic and/or loads on the roof during and after installation are the primary causes of this undesired effect. A disproportionate share of cases has occurred on projects with insulation greater than 3″ in thickness. It is apparent that preventive factors could be used, such as reducing traffic on the roof and requiring multiple layers of insulation not to exceed 3″ per layer. For areas of known or expected excessive traffic and/or heavy loads, there are similar preventive factors to address facer delamination concerns. Walkway pads are an excellent way to protect the membrane from traffic loading. Composite and cover board insulations offer protection from under the membrane but may present other concerns such as potential puncture resistance reduction and high water absorption rates that may negatively affect the performance of the roof. Practical as these measures are, they do not truly address the source of the concern but rather address only the symptoms. Some roofing professionals have suggested that requiring a greater compressive strength for the polyisocyanurate insulation is a more functional solution; for example, specifying a compressive strength of 25 psi instead of 20 psi. Presumably, the theory is that increased compressive strength will offer greater resistance to traffic on the roof and reduce the potential for delamination. Our studies, however, find no correlation between increasing the compressive strength and a reduced occurrence of facer delamination. It is noteworthy to point out that the desired feature of the product, when considering the issue of facer delamination, is not necessarily the strength of the foam or facer but the insulation board’s durability. Standard facer adhesion tests have not successfully addressed the questions raised by the roofing industry for such incidents. Current testing methods do not accurately portray field conditions that the insulation must withstand. These factors present a need in the industry for a test that accomplishes two purposes. The first purpose of the test should be to more realistically simulate actual field conditions. The second purpose should be to predict an insulation’s ability to withstand those typical field conditions. It is with these goals in mind that a team from Firestone Building Products set out to find a practical procedure that would test product coming off the production line and economically, yet substantially, determine its ability to perform under typical field conditions. The result of this research is the development of the Rolling Load Emulator (RLE). The Rolling Load Emulator The RLE is a testing device designed to measure a polyisocyanurate insulation board’s ability to resist facer delamination by reproducing the effects of a rolling load (i.e. wheelbarrow or gravel buggy) over a sample of insulation. See Photo 1. The greater number of passes of the rolling load over the sample correlates to a greater resistance to facer delamination. In effect, it measures the durability of the insulation board. The RLE test enables the user to achieve both purposes sugPhoto 1—The Rolling Load Emulator. June 2001 Interface • 7 gested above. First, by repeatedly applying a weighted load over the surface of the insulation sample, it imitates some of the rigors of equipment and foot traffic on the roof in a concentrated area. Second, the test has proven to produce data that reliably indicate the suitability of the insulation for fullyadhered applications. As the weight is rolled over the insulation sample on the RLE, the number of passes is electronically recorded. The greater the number of passes without facer damage indicates a greater resistance to facer delamination. A visual inspection of the sample being tested determines the percentage, if any, of the facer that may be delaminated. The chart below provides an excellent example of the helpful data that the RLE test produces. It compares results of samples of 4″ polyisocyanurate insulation using the RLE, facer adhesion, and compressive strength tests. A 4″ sample was selected because it presents what would be considered the worstcase scenario regarding the thickness of the board and potential for facer delamination. According to the theory that higher compressive strength and facer adhesion results lead to a lesser likelihood for delamination, one would presume that Sample B, with higher results for both tests, would perform better on the RLE. However, Sample A actually performed 6.4 times better on the RLE than Sample B. No insulation board is immune to facer delamination or severe compression when traffic is high enough and/or the load placed on it is heavy enough. However, the RLE can be used effectively as a quality control tool to predict board resistance to facer delamination. RLE tests are conducted in each of Firestone’s manufacturing facilities throughout the country and at its technology center in Carmel, Indiana. Since regularly conducting these tests, the data have been applied to improve the manufacturing process of polyisocyanurate insulation. At $3,600 per RLE apparatus and the associated time required to test the insulation, this test adds a substantial cost factor to quality control procedures. Fortunately, such costs have been offset at Firestone Building Products by a dramatic decrease in the number of incidents of facer delamination. Besides the economic benefits of these improvements to the manufacturer, the specifier and contractor have fewer problems to deal with, and the owner has a more durable roof. Despite the competitive advantage that the RLE provides, as a service to the industry, Firestone has brought the RLE testing procedure to the attention of the leading roofing organizations. Based on positive results, the RLE testing apparatus has been presented to the National Roofing Contractors Association (NRCA) Technical Committee, Polyisocyanurate Insulation Manufacturers Association (PIMA), Single Ply Roofing Institute, American Society for Testing and Materials (ASTM), and at the North American Conference on Roofing Technology (Toronto, Canada) 1999. Individuals from of each of these organizations have agreed Photo 2— A worker installs board insulation. the roofing industry would benefit from uniform standards for the Rolling Load Emulator test. When these standards are established, specifiers of insulation as a part of roofing systems will reduce the risk of potential facer delamination. Conclusion Reducing the potential for facer delamination in fullyadhered roofing systems can be achieved by reducing traffic on completed portions of the roof during installation and limiting access to the roof upon completion. A greater use of walkway pads, composite boards, and cover boards can also provide an effective barrier for protecting against delamination, especially in high traffic and/or heavy load areas. The Rolling Load Emulator provides a testing apparatus that can simulate field conditions, and its data can be instrumental in predicting an insulation board’s ability to resist delamination under normal installation and ongoing circumstances. The RLE test has proven to be a very successful tool in the continuing quality control process at Firestone Building Products. Once adopted, a minimum acceptable level of resistance to facer delamination may become a final product requirement. Implemented as diligent quality control at the point of manufacture, this new standard would significantly reduce the occurrence of facer delamination. It is to the benefit of the entire industry for testing procedures and standards to be established so that manufacturing processes can be improved and performance characteristics can be more clearly specified. ■ This article was written with contributions from John B. Letts Ph.D., Firestone Building Products, Technical Director, Insulations; and Tim Tackett, Firestone Building Products, Laboratory Manager. John Geary, a business graduate of the University of Illinois at UrbanaChampaign, has been involved in the roofing industry since 1982 and is the Insulation Product Manager for Firestone Building Products, Carmel, Indiana. ABOUT THE AUTHOR JOHN GEARY 8 • Interface June 2001
