«THE WIND RESISTANCE OF ASPHALT ROOFING SHINGLES By CRAIG ROBERT DIXON A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN ...»
THE WIND RESISTANCE OF ASPHALT ROOFING SHINGLES
CRAIG ROBERT DIXON
A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA© 2013 Craig Robert Dixon To my Mom
ACKNOWLEDGMENTSFirst and foremost, I would like to thank my advisors, Drs. David O. Prevatt, Forrest J. Masters, and Kurtis R. Gurley for their guidance, support, and friendship. This work would not have been accomplished without their mentoring. I would also like to thank my external committee member – Dr. Bhavani Sankar.
Additionally, I would like to thank my friends in the wind engineering group for their help in various aspects of my research, especially: Dany Romero, Kenton McBride, Daniel Smith, Scott Bolton, David Roueche, Alon Krathammer, Tuan Vo, and Peter Datin. I would also like to thank the research oversight committee for their valuable input, especially: Dr. Jon Peterka, Tom Smith, Dr. Ben Thomas, and Dr. Walt Rossiter.
Finally, I wish to thank my mom for being a source of intelligence and strength.
The financial support for this research is gratefully acknowledged from the Southeast Region Research Initiative under grant #10031592 – Residential Roof Covering Investigation of Wind Resistance of Asphalt Shingles. I am also grateful to the financial support of the Florida Building Commission and Florida Department of Emergency Management.
TABLE OF CONTENTSpage ACKNOWLEDGMENTS
LIST OF TABLES
LIST OF FIGURES
CHAPTER 1 INTRODUCTION
Knowledge Gaps in the Wind Resistance of Asphalt Shingles
Research Goals and Scope
Layout of the Dissertation
2 ASPHALT SHINGLE COMPOSITION AND INSTALLATION
Asphalt Shingle Installation
3 LITERATURE REVIEW
The Early Years (1893 – 1950)
Development of the First Test Standards for Wind Resistance (1950 – 1980)....... 45 The Development of the Asphalt Shingle Wind Uplift Model (1980-1997).............. 50 The Modern Era (1997- )
The ASTM D6381 Asphalt Shingle Mechanical Uplift Resistance Test Method
In-Service Wind Performance of Asphalt Shingles
4 UNSEALED NATURALLY AGED ASPHALT SHINGLES AND THEIRVULNERABILITY IN WIND
Study 1: Survey of Naturally Aged Shingle Roofs for Unsealed Shingles............... 68 Survey Method
Potential for Wind Induced Loss of Shingle Sealing
Shingles in the field of the roof
Ridge and hip shingles
Study 2: Full-Scale Testing of Asphalt Shingle Roof Systems
Wind Test Sequence and Boundary Layer Simulation
Pre-wind test unsealed shingle surveys
Wind performance of shingles installed in the field of the roof
Hip shingle wind performance
5 WIND RESISTANCE OF NATURALLY AND ARTIFICIALLY AGED ASPHALT SHINGLES
Aging of Asphalt Shingles
Study 1: Wind Uplift Capacity of Asphalt Shingles Subjected to Artificial Aging..... 96 Experimental Setup
Shingle specimen specifications
Thermal aging – chamber specifications and protocol
UV-Thermal-Water aging – chamber specifications and protocol.............. 98 ASTM D6381 Mechanical Uplift Test Procedure
ASTM D6381 Procedures A and B uplift resistance
Failure modes in uplifted shingles
ASTM D7158 total wind uplift resistance
Study 2: Naturally Aged Shingle Wind Uplift Resistance
Portable Mechanical Uplift Apparatus
In Situ ASTM D6381 Specimen Preparation and Test Procedure.................. 117 Results
In situ ASTM D6381 mechanical uplift resistance
ASTM D7158 total wind uplift resistance
Discussion of Combined Results
6 THREE-DIMENSIONAL MEASUREMENTS OF WIND FORCE ON ASPHALTSHINGLE SEALANT STRIPS WITH FULL AND PARTIAL ADHESION............... 125 Knowledge Gaps
Wind Load Model and Load Path
Partially Unsealed Shingles
Test Deck Specifications
Multi-Axis Load Cell Specifications
Velocity Sensor Specifications
Test Specimen Installation
Phase I: Wind Field Above the Test Specimen
Mean longitudinal velocity
Longitudinal turbulence intensity
Discussion on Turbulence
Phase II: Effect of Static Pressure on Shingle Test Specimens
Phase III: Wind-Induced Forces and Moments on the Shingle’s Sealant Strip
Fully sealed shingle results – mean forces and moments
Fully sealed shingle results – force coefficients
Partially unsealed shingle results – measured forces and moments........ 166 Partially unsealed shingle results – interfacial forces
Partially unsealed shingle results – force coefficients
7 CONCLUSIONS AND RECOMMENDATIONS
Conclusions on the Causes of Wind Damaged Asphalt Shingle Roofing.............. 181 Partially Unsealed Shingles
Effect of Aging on Wind Resistance
ASTM D7158 and the Load Model for Asphalt Shingles
ASTM D7158 Design Methodology
Eave and Rake
Recommendations for Future Research
LIST OF REFERENCES
1-1 Oversight committee members
2-1 Wind classification required for asphalt shingle installed in Florida
3-1 Wind-tunnel-measured three-tab shingle with cutouts
3-2 Summary of standardized test methods to evaluate asphalt shingle wind performance
4-1 Estimates of peak instantaneous velocity near the roof plane at each survey location
4-2 Wind test sequence duration, wind speeds, and turbulence intensities.............. 83 5-1 Exposure times where ASTM D6381 tests were performed
5-2 Mean resistance in Thermal and UV-Thermal-Water methods
5-3 Specimen dimensions, ASTM D7158 differential pressure coefficients, and ASTM D7158 required resistance
5-4 Mean and lowest measured wind uplift resistance vs. ASTM D7158 Class H required wind resistance.
5-5 Test site location, age, type, and quantity of ASTM D6381 tests
5-6 Test site differential pressure coefficients, length dimensions, and ASTM D7158 Class H required wind uplift resistance.
6-1 Test specimen ID, type, planform dimensions, and number of specimens....... 135 Test specimens’ exposed lengths and ASTM D7158 differential pressure 6-2 coefficients
6-3 Force coefficients and relative contribution of ASTM D6381 Procedures A and B to total uplift
6-4 Six-axis load cell sensing ranges and resolutions
6-5 Longitudinal integral length scales measured 12 mm above shingle surface... 153 6-6 Mean forces and moments measured on fully sealed Laminate specimens..... 160 6-7 Mean forces and moments measured on fully sealed Three-Tab specimens... 162 6-8 Laminate force coefficients directly measured vs. ASTM D7158 predicted...... 164 6-9 Three-Tab force coefficients directly measured vs. ASTM D7158 predicted.... 165 6-10 Mean forces and moments measured on partially unsealed Laminate specimens
6-11 Mean forces and moments measured on fully sealed Three-Tab specimens... 168 6-12 Laminate Specimen 3 - measured moments and estimated interface forces... 172 6-13 Laminate Specimen 4 - measured moments and estimated interface forces... 172 6-14 Three-Tab Specimen 4 - measured moments and estimated interface forces. 173 6-15 Three-Tab Specimen 5 - measured moments and estimated interface forces. 173 6-16 Three-Tab Specimen 6 - measured moments and estimated interface forces. 174 6-17 Laminate force coefficients directly measured vs. ASTM D7158 predicted...... 176 6-18 Three-Tab force coefficients directly measured vs. ASTM D7158 predicted.... 176
2-1 Asphalt shingles are installed in the field of the roof with additional shingles along hip and ridge lines.
2-2 Plan view of a standard three-tab shingle with six fastener locations shown...... 25 2-3 Exploded view of a three-tab asphalt shingles constitutive materials................. 25 Location of sealant strip relative to the shingle’s leading edge and fasteners.... 28 2-4 2-5 Plan view of typical laminate shingle with six-fastener pattern shown................ 34 2-6 Exploded view of typical laminate shingle constitutive materials.
2-7 Diagonal installation of three-tab asphalt shingle system. Laminate installation produces a similar pattern.
2-8 Vertical (racked) installation of three-tab asphalt shingle system. Laminate shingles are not installed with this pattern.
3-1 Pre-wind test asphalt shingle test deck
3-2 Post-wind test asphalt shingle test deck
3-3 Wind load model proposed by Peterka et al. (1983).
3-4 Test setups for wind testing of asphalt shingles
3-5 Peak pressure coefficients measured on a full-scale asphalt shingle subjected to wind flow from varying directions
4-1 Locations of the asphalt shingle surveys conducted in Florida.
4-2 Location of partial unsealing.
4-3 Location of partially/fully unsealed three-tab and laminate shingles (tape marks).
4-4 Shingle roofs located in Houston, TX with partially unsealed shingles located by triangular chalk marks and fully sealed shingles located by dash marks....... 75 4-5 Percent of unsealed shingle strips located in the field of the roof verses roof age.
4-6 Boxplot of unsealed shingle strips located in the field of the roof verses roof age at the time of investigation.
4-7 Blown off three-tab asphalt shingles.
4-8 Typical condition for partially unsealed ridge and hip shingle.
4-9 Percent of fully and partially unsealed hip and ridge shingles
4-10 Wind directions for gable and hip roof specimens.
4-11 Measured and best-fit theoretical normalized mean velocity, longitudinal turbulence intensity, and lateral turbulence intensity.
4-12 Normalized wind spectrum of Wind Level 3 (measured at 5 m)
4-13 Hip roof three-tab shingle specimen pre- and post-test conditions
4-14 Shingle roof damage initiated by pre-wind test unsealed shingles.
4-15 Statistical comparison of roof damage for the roof specimen shown in Figure 4-13.
4-16 Characteristic hip shingle blow off patterns.
4-17 Progression of hip shingle blow off through the wind test sequence for specimen oriented at the 0° wind direction.
5-1 Wind pressures on shingle roofing.
Cross-section view of a shingle’s constitutive materials.
5-2 5-3 ASTM D6381 specimens.
5-4 UV-Thermal-Aging chamber components.
5-5 Measured irradiance, plan view, and temperature time-history of one cycle.... 100 5-6 ASTM D6381 test apparatus, setup, and uplifted specimen.
5-7 ASTM D6381 test results for Product A.
5-8 ASTM D6381 test results for Product B.
5-9 ASTM D6381 test results for Product C.
5-10 Example failure modes observed in mechanically uplifted shingles................. 109 5-11 Distribution of failure modes on Product A-Procedure A.
5-12 Distribution of failure modes on Product A-Procedure B.
5-13 Distribution of failure modes on Product C.
5-14 Portable Mechanical Uplift Apparatus components.
5-15 In situ ASTM D6381 test results.
5-16 Distribution of failure modes for in situ ASTM D6381 tests.
5-17 Wind resistance of naturally aged shingles vs. ASTM D7158 Class H required resistance.
6-1 Wind pressures on shingle roofing.
6-2 Rendering of the Dynamic Flow Simulator componentry.
6-3 Dynamic Flow Simulator, profile view, and test section, orthogonal view......... 132 6-4 Dynamic Flow Simulator, as constructed.
6-5 Cross-section of DFS test section.
6-6 Test deck below opening in test section.
Interior view of the DFS during this study’s wind test. A partially unsealed 6-7 laminate shingle instrumented with load cells is shown.
6-8 Mean longitudinal velocity across the width of a shingle test specimen........... 134 6-9 Plan view of Three-Tab test deck.
6-10 Plan view Laminate test deck.
6-11 Cross-section of DFS with test deck.
6-12 Multi-axis load cell elevation and plane view.
6-13 Cross-section of load cell attachment detail.
6-14 Part 1: load cell arrangement for Laminate specimen showing load cell base connection.
6-15 Part 2: load cell arrangement for Laminate specimen showing wood decking surrounding top plates.
6-16 Three-Tab specimen.
6-17 Plan views for Three-Tab fully sealed and partially unsealed arrangements.... 144 6-18 Laminate specimen.
6-19 Plan views for Three-Tab fully sealed and partially unsealed arrangements.... 145 6-20 Fully sealed laminate test specimen installed on the test deck.
6-21 Plan view and cross section of velocity measurement locations.
6-22 Velocity sensor test setup.
6-23 Mean longitudinal velocity profiles – Low wind speed.
6-24 Mean longitudinal velocity profiles – Medium wind speed.
6-25 Mean longitudinal velocity profiles – High wind speed
6-26 Mean longitudinal velocity of all measurement positions and wind speeds normalized by the 152 mm height mean.
6-27 Mean longitudinal velocity of all measurement positions and wind speeds...... 152 6-28 Phase II experimental setup.