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Evolution of Modern Commercial Roofing Materials

Explore the historical perspective, innovative materials, and emerging trends in commercial roofing, from built-up roofing to modern membranes. Learn about the impact of sustainability and durability on the commercial roofing industry.

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Evolution of Modern Commercial Roofing Materials

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  1. INTRODUCTION TO COMMERCIAL ROOFING James L. Hoff, DBA

  2. Commercial Roofing • Historical Perspective • Modern Roofing Materials • Membranes • Insulations • New Roofing Trends

  3. Introduction to Commercial Roofing A Brief History of Commercial Roofing

  4. Historical BackgroundPre-1900: Before the Modern Age • Roofing materials selected for durabilityand appearance • Slate • Tile • Metal • Roofing systems designed to shed water • Gables • Hips • Valleys • Crowns • Saddles • Gutters • Downspouts

  5. Historical Background1920s : The Bauhaus • Lightweight Framing Systems • Roof weight becomes a consideration • Rectangular, Low-Rise Profiles • Roof plane becomes virtually level • Facades and Parapets • Roof becomes an isolated sump As a result, roofing materials were selected on the basis of durability and weight, while roof systems were designed to resist water.

  6. Historical BackgroundToday : The “Big Box” What started as architectural theory is now economic fact “Steeply sloped roofs on the large, sprawling buildings that dominate today’s construction would dramatically cut the costs of re-roofing, repair and litigation. but they would raise construction costs by a far greater amount …the costs of steeply sloped roofs over the vast acreages covered by modern buildings are simply too high a price to pay to avoid the problems posed by low-slope roof systems.” (C. W. Griffith & R. Fricklas, Manual of Low-Slope Roofing Systems, 1996)

  7. Historical Background1840s – 1970s: Built-Up Roofing

  8. Historical Background1840s – 1970s: Built-Up Roofing • Originally employed to waterproof ships • Redundant layers of bitumen & felts • Bitumen serves as adhesive and waterproofing • Felts stabilize and strengthen the bitumen • Frequently surfaced with aggregate • Traditional “tar & gravel” roof

  9. Historical Background1840s – 1970s: Built-Up Roofing • Dominated commercial roofing for over a century • Provided a satisfactory barrier to water entry • Success attributed to redundancy of design and well-understood application standards

  10. Historical Background1970s: The Perfect Storm • Asbestos health concerns • Traditional roofing “felts” relied on asbestos fibers for strength • Asbestos fibers replaced by lower strength organic (paper) fibers • OPEC oil embargo • Quality of roofing asphalt decreased as more gasoline was extracted from every barrel of oil • Roofing asphalt became more brittle, less plastic

  11. Historical Background1970s: The Perfect Storm • The response: Roof insulation increased to save energy • “R” value doubled or tripled • Roof surface isolated from building interior • Roof surface daily temperature swings up to 150ºF • The result: Premature roof aging & failure • Non-asbestos felts lacked strength and moisture resistance • Asphalt became brittle

  12. Historical Background1970s: New Answers – And Plenty of Them • Tire manufacturers introduce Rubber Roofing Neoprene, Butyl, EPDM • Textile manufacturers introduce Thermoplastic Roofing PVC, PE, CPE, CSPE, E-P, TPO • Asphalt manufacturers introduce Polymer Modifiers APP, SBS, SEBS “According to industry estimates, over 100 new manufacturers of roofing products emerged during the ‘70s and early ‘80s, each offering the ‘miracle’ answer for roofing performance.” (J.L. Hoff, “The Commercial Roofing Industry: New Directions in Construction Quality”, 2003)

  13. Historical Background1980s: A Steep Learning Curve • Rubber roofing: Leaks at adhesive seams • Thermoplastic roofing: Membrane cracking • Modified bitumen roofing: General workmanship issues

  14. Historical Background1980s: The Lesson for the Roofing Industry "As an industry, we have spent far too much time and far too many dollars fixing past problems related to durability not to become unflinching advocates for the utmost importance of durability…” James L. Hoff. “Advancing Sustainable Roofing: LEED and the Commercial Roofing Industry." Proceedings of the 20th International Convention of the Roof Consultants Institute, Miami Beach, Florida, March, 2004.

  15. Historical Background1990s: Consolidation / Standardization • Rubber roofing consolidates around EPDM • New seaming technologies dramatically reduce leaks • Thermoplastic roofing consolidates around PVC & TPO • Improved formulations offer long-term stability • Polymer modification (APP & SBS) integrates into traditional asphalt roofing • Hybrid asphalt roofs use a combination of traditional BUR with modified flashings and cap sheets

  16. Introduction to Commercial Roofing Modern Roofing Materials

  17. U.S. Low-Slope Commercial Roofing Market Key Membrane Segments (Millions of Square Feet, 2003) Single-Ply Asphalt Built-Up Roofing (BUR) Rubber Roofing (EPDM) 17% 30% 30% 23% Thermoplastic (PVC & TPO) Modified Asphalt (APP & SBS) Source: TEGNOS Research Estimate

  18. Modern Roofing MembranesSingle-Ply • THERMOSET • EPDM • THERMOPLASTIC • PVC • TPO

  19. Modern Roofing MembranesEPDM • Large panel sizes for fast coverage • Outstanding resistance to weathering • High elongation to accommodate building movement

  20. Simple, economical design provides proven performance • Stone ballast provides Class A fire rating • Compatible with most insulations • Large panels provide efficient coverage of large roof areas Modern Roofing MembranesEPDM: Ballasted System Stone Ballast or Pavers Membrane Insulation Deck

  21. Modern Roofing MembranesEPDM: Ballasted System

  22. Modern Roofing MembranesEPDM: Ballasted System

  23. Adhesive Adhesive Modern Roofing MembranesEPDM: Adhered System Membrane Insulation plates & fasteners Deck Insulation • Design Flexibility - Adapts easily to unusual roof profiles • Excellent for high wind conditions • Time-proven application method provides high dependability

  24. Modern Roofing MembranesEPDM: Adhered System

  25. Modern Roofing MembranesEPDM: Adhered System

  26. Modern Roofing MembranesEPDM: Mechanically Attached Metal Or Polymer Batten Membrane Embedded In Field Seam Deck Seaming Tape Insulation • Light weight - adapts to most roof decks • Reduced labor input

  27. Modern Roofing MembranesEPDM: Mechanically Attached

  28. Modern Roofing MembranesEPDM: Mechanically Attached

  29. Modern Roofing MembranesThermoplastic • Heat-reflective white surface • Fast, simple welded panel seams • Available in variety of colors

  30. Modern Roofing MembranesThermoplastic Installation

  31. Modern Roofing MembranesThermoplasticInstallation Ice Mountain Bottling Stanwood, MI

  32. Modern Roofing MembranesAsphalt • Built-Up Roofing • BUR • Modified Bitumen • APP • SBS

  33. Modern Roofing MembranesBuilt-Up Roofing (BUR) Gravel Surfacing Cover Board Insulation Ply Felts Set In Asphalt

  34. Modern Roofing MembranesBuilt-Up Roofing (BUR) Roofing Felts in Hot Asphalt

  35. Modern Roofing MembranesBuilt-Up Roofing (BUR) Gravel-Surfaced BUR

  36. Modern Roofing MembranesModified Bitumen

  37. Modern Roofing MembranesModified Bitumen Cap Sheet Cover Board Insulation Base Sheet

  38. Modern Roofing MembranesModified Bitumen Asphalt Modifiers • SBS • Styrene-Butadiene-Styrene • Thermoset (Rubber) Polymer • Adds Flexibility & Memory • Excellent Low Temp. Flexibility • Requires uV Resistant Surfacing • APP • Atactic Polypropylene • Thermoplastic Polymer • Adds Flexibility • Excellent High Temp. Strength • Excellent uV Resistance

  39. Modern Roofing MembranesModified Bitumen Hot Mopped Torch Applied Cold Applied

  40. Modern Roofing MembranesModified Bitumen

  41. Modern Roofing MembranesModified Bitumen Miami Beach Convention Center Miami Beach, FL Swenson Skills Center Philadelphia, PA

  42. Modern Roofing MembranesHow Long Do They Last? Membrane Type Single-Ply Built-Up Roofing Modified Bitumen Average Service Life 16.8 – 18.4 Years 13.6 – 18.1 Years 17.6 – 18.2 Years “A documented historical performance of roofing assemblies in the United States: 1975–1996”. K. G. Schneider & A. S. Keenan.. Proceedings of the Fourth International Symposium on Roofing Technology (pp. 132-137). Rosemont, IL: National Roofing Contractors Association, 1997. “…Life span is defined as the time period from the initial roofing membrane installation through recover/re-roof. Based on the results of the statistical model, the current average low slope roofing life span is estimated to be 17.45 years” “Comprehensive Nonresidential Building Analysis to Estimate the Current Reality of Roofing Longevity”, Ducker Research, 2003.

  43. Modern Roofing Membranes Performance Features • Ultraviolet Aging • Roof Traffic • Chemical Exposure • Building Movement • Reflectivity • Color Options • High Production • Work Area Limitations • Relative Cost EPDM +++ + +++ +++ ++ 1.0 - 1.2 PVC/TPO + + + (PVC) + ++ ++ ++ ++ 1.1 - 1.3 BUR + +++ ++ 1.2 - 1.4 Mod Bit + ++ + +++ + +++ 1.1 - 1.3

  44. Modern Roofing Materials Roof Insulation One Component Three Functions

  45. Roof Insulation: Thermal Barrier Typical “R” Value per Inch Thickness

  46. Roof Insulation:Working Platform

  47. Roof Insulation:Drainage Structure

  48. Roof InsulationDrainage Issues Typical 2-Way Structural Slope Slope

  49. Roof InsulationDrainage Issues Interior Drain (Typ.) Typical 2-Way Structural Slope

  50. Roof InsulationDrainage Solution 4-Way Slope using Tapered Insulation Detailed Tapered Roof Insulation Plan

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