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Randy D. Denchfield, President of Denchfield Roofing Corporation, has over 38 years of experience in the roofing industry. He has participated in several studies with NIST (National Institute of Standards and Technology) and NRCA (National Roofing Contractors Association) on the performance of a variety of roof systems. These opportunities have given him the chance to evaluate how different roof systems perform. During this time, he has had the opportunity to see these systems perform in all types of weather conditions such as thermoshock and ice. These studies have looked at and compared coated and un-coated membranes, excessive ponding, marginal workmanship and abuse by others.


The real cost of a roof system is not in its initial cost but in its life-cycle cost. A NIST field report entitled Field Performance Research of APP Modified Bitumen Roof Membranes and Coatings illustrates a 12-year old Derbigum APP multiple-reinforced modified bitumen roof which shows very little weathering effect and no visible signs of deterioration. It states that the single-reinforced APP modified bitumen membranes of five major manufacturers showed signs of cracking and crazing within 19 months of installation. The study stated that Derbigum will perform 25 years plus of service.


All roofs installed by manufacturer specifications and warranty should provide 10 years of service. After that period the roof longevity is due to the type of roof and its accessories. Two of the most stressful items on the roof are excessive ponding and abuse by trades. These items are more significant on 0.45 and 0.60 single-ply membranes and are not covered by the roof manufacturer warranty. Roofing manufacturers provide an option to specify tapered insulation to provide positive drainage or install roof drains where necessary.


Utilizing proven European technology, Derbigum has surface-located multiple-reinforcements (polyester and fiberglass mat) to provide unequaled protection of the modified bitumen membrane from roof traffic, abuse and the sun’s ultra-violet rays. The careful selection and control of the raw material sources with the precise limitations of fillers creates an APP modified bitumen which has the ideal weathering characteristics to produce superior long-term aging properties. Notable roofs which have been installed with Derbigum are the Pantheon in Rome, Italy; McCormick Place in Chicago, Illinois; The White House and the National Roofing Contractors Association’s Legislative Offices in Washington, D.C.


Denchfield Roofing Corporation is one of the largest and longest users of Derbigum in the USA. Our employees’ constant use of a system we know well allows us to perform at our highest level of expertise. Five of our foremen have been recognized for NRCA's National MVP Award - Mid-Atlantic Region (our foremen winning recognition five years in a row). Listed below are some Derbigum roofs installed by Denchfield Roofing Corporation over the last 20 years. We invite you to personally inspect any or all of these roofs to evaluate the workmanship and see how they have performed over the years.

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