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Performance evaluation of thermoplastic polyolefin (TPO) roof
membranes weathering on full-scale test roofs in four different climatic areas of North America
http://www.nrc-cnrc.gc.ca/irc
Pe rform a nc e e va lua t ion of t he rm opla st ic polyole fin (T PO) roof m e m bra ne s w e a t he ring on full-sc a le t e st roofs in four diffe re nt c lim a t ic a re a s of N ort h Am e ric a
I R C - O R A L - 9 9 1
C a r l s o n , J . D . ; E l l i o t , S . ; D e l g a d o , A . H . ; P a r o l i , R . M . u t h o r
O c t o b e r 2 0 0 9
A version of this document is published in / Une version de ce document se trouve dans:
Waterproof Membranes 2009 Conference, Dusseldorf, Germany, October 19-21, 2009, pp. 2,
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WESTERN STATES ROOFING CONTRACTORS
ASSOCIATION (WSRCA)
Project with field work by WSRCA and laboratory work by
NATIONAL RESEARCH COUNCIL OF CANADA (NRC)
TPO ROOF MEMBRANE
IN-SITU TESTING &
RESEARCH PROGRAM
Analysis of First Five-Years of
Field Observations and Laboratory Test Findings, but first a bit of background info….
Built-up Roof BUR SBS Styrene-Butadiene-Styrene (Elastomer) APP Atactic Polypropylene (Plastomer) Modified Bitumen (Mod. Bit.) Asphalt-based CR (Polychloroprene) EPDM (Ethylene-Propylene-Diene Monomer or Ethylene-Propylene-Diene Terpolymer) Thermosets (TS) CSPE (chlorosulphonated Polyethelene) CPE (Chlorinated Polyethylene) TPO (Thermoplastic Polyolefin or Flexible Polyolefin) KEE
(Ketone Ethylene Ester)
PVC
Poly(Vinyl Chloride)
Theromplastics (TP) Polymer-based
Low Slope Roof Membranes
Genre of Low-Slope Roof Membranes Used In the Western United States
How Do TPO Roof Membranes Stack Up?
General U.S. Experience:
•
Mostly Successes to Date• History has shown that almost no membrane roof system has been immune to issues or some sort of problem:
- BUR (blistering of organic felts, slippage, etc.) - Mod Bit (earlier APP cracking and weathering) - PVC (aged, unreinforced membrane shrinkage,
cracking, shattering)
- EPDM (shrinkage and bridging)
- Etc. (including TPO has been no different than others)
Earlier Generation TPO Roof Membrane
Issues Included:
• Some Problems with 1st Generation Sheets: - Welding issues and seam problems
- Complications with fire retardants and UV stabilizers
• Other Issues Have Developed with Early Generation Sheets:
- Surface crazing and top coating cracking, particularly with darker-colored sheets
Example of surface crazing and cracking
with earlier generation sheets
Microscopic view of
initial crazing
Crazing more
pronounced over scrim
Early TPO Issues, Such as
1st Generation Membrane Cracking What do we tell our clients, and
what do we do about it?
With most membranes, problematic seams can be treated as a repair and maintenance
measure
Sheet seams can be stripped in to repair cracking along seams. If membrane warranty expired, and field of
membrane in serviceable condition – candidate for repair and maintenance or service contract.
1stGeneration Membrane Cracking along
WSRCA’s Low-Slope Technical & Research Committee Chose Proactive Research with Full-Scale Testing:
WSRCA TPO WEATHERING FARM
Inception January, 2000
Participating Manufacturers (in alphabetical order)
• Carlisle
• Firestone
• Genflex (Now owned by Firestone)
• Stevens Roofing Systems (Now Dow)
Participating Roofing Contractors (listed in chronological order that roofs were installed)
• Snyder Roofing, Snohomish, Washington
• Industrial Roofing, Anchorage, Alaska
• Commercial Roofers, Las Vegas, Nevada
Program Purpose
To examine weathering characteristics of
Thermoplastic Polyolefin (TPO) roof membranes by exposing them to various weather conditions of four distinctly different climatic regions in the Western United States.
Program Goal
To provide pertinent technical and performance information to the Western States Roofing
Contractors Association membership, and the U.S. roofing industry at large, regarding TPO roof
membranes’ attributes, their performance properties and resistance to degradation due to the effects of weathering.
The TPO roof membranes are applied in-situ on full-scale test roofs located in the following climatic areas:
• Hot and Dry
• Hot and Humid
• Cold and Dry
• Moderate and Wet
Anchorage, Alaska San Antonio, Texas
Anchorage, Alaska TPO installation
WSRCA’s Low-slope Committee and the Manufacturer Participants Agreed to Yearly Field Inspections, Examining Numerous Items, Including:
• Seam Integrity
• Physical Condition of Surface
• Coefficient of Expansion
(Visible changes in tightness vs. looseness)
• General surface hue and appearance differing from the time of installation
WSRCA’s Low-slope Committee and the Manufacturer Participants Agreed to Testing of Samples According to Standard Test Methods
• Membrane Total Mil Thickness from random field locations
• Coating Thickness over scrim
• Dimensional Stability
• Water Absorption
• Tensile Strength
• Low Temperature Properties, and added
4,860 Sq.Ft. 4,600 Sq.Ft. Area 1 Area 2 4,700 Sq.Ft. 4,860 Sq.Ft. Area 3 Area 4 Area Dividers
Commercial Facility, Near Seattle, Washington
1,200 Sq.Ft. 1,200 Sq.Ft. 1,200 Sq.Ft. 1,200 Sq.Ft. Area 4 Area 3 Area 2 Area 1
Medical Building, Anchorage, Alaska
Commercial Facility, Las Vegas, Nevada
3,600 Sq.Ft. 3,330 Sq.Ft. 3,510 Sq.Ft. 3,870 Sq.Ft.
Shopping Center, San Antonio, Texas
2,176 Sq.Ft. 2,135 Sq.Ft. 2,178 Sq.Ft. 2,192 Sq.Ft.
Seattle, WA
Year 3 – Year 5 Comparison
Observed Changes - 1. Dimensional Stability
Membrane tightening observed, but it still continues to change a bit with temperature and sun conditions as is characteristic with
TPO compounds.
Seattle Area 1, Year 3
Note: Wrinkles Across Sheets (cross-machine direction)
Seattle Area 1, Year 5
Note: Membrane Tighter During Site Visit Two Years Later
Seattle Area 2, Year 3
Note: Wrinkles Along Length of Sheets (in machine direction)
Seattle Area 2, Year 5
Note: Membrane Tighter Two Years Later -- Though Creases
Seattle Area 3, Year 3
Note: Numerous Wrinkles in Various Directions
Seattle Area 3, Year 5
Though Some Wrinkles Remain, Membrane More
Seattle Area 4, Year 3
Note: Some Wrinkles with Length of Sheet
Seattle Area 4, Year 5
Membrane Taut, Though Crease Remains Along Seam
Observed Performance Changes
2. Some Slight Bridging at Angle Change
Las Vegas Site – 3 Years
Some bridging at angle changes
Example of more pronounced bridging
Seattle, WA
Roof Area 1 Roof Area 2
Roof Area 1 Las Vegas, NV Roof Area 2 Surface Characteristics, Color/Hue
Observed Changes
Requirement for Energy Star Label
Initial Solar Reflectance
Greater than or equal to 0.65
Maintenance of Solar Reflectance
Greater than or equal to 0.50 three years after initial installation under normal weathering conditions
Solar Reflectivity Testing
Solar Reflectometer – Thanks Firestone!
Seattle, Reflectivity Testing
Reflectivity Testing at Cleaned Area
--Decided to compare two different methods
Pressure Wash to Clean Surface
Rinse, Scrub, Rinse, and Squeegee
AGE OF
ROOF 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 AVERAGE
New - - -
-Average: 0.826 Average: 0.826 Average: 0.826 Average: 0.826 0.826 7-Month - - - 0.670 0.657 0.676 0.668
Average: - Average: - Average: - Average:* 0.668 0.668 3-4 Year 0.720 0.595 0.603 0.626 0.693 0.721 0.654 0.701 0.000 0.000 0.000 0.000 0.683 0.605 0.618 0.656
Average: 0.636 Average: 0.692 Average: 0.000 Average: 0.641 0.656 Elapsed Change: - 0.190 Elapsed Change: - 0.125 Elapsed Change: - - Elapsed Change: - 0.186 0.170
* Unofficial test results taken only at Seattle TPO Test Roof
AGE OF
ROOF 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 AVERAGE
New - - -
-Average: 0.826 Average: 0.826 Average: 0.826 Average: 0.826 0.826 3-4 Year 0.774 0.680 0.681 0.723 0.746 0.761 0.742 0.783 0.000 0.000 0.000 0.000 0.713 0.628 0.669 0.732
Average: 0.715 Average: 0.758 Average: 0.000 Average: 0.686 0.719 Elapsed Change: - 0.112 Elapsed Change: - 0.068 Elapsed Change: - Elapsed Change: - 0.141 0.107
ROOF AREA ROOF AREA ROOF AREA ROOF REA
CLEANED ROOF AREA TEST COMPARISONS FROM REGIONAL LOCATIONS
Anchorage, Alaska Las Vegas, Nevada San Antonio, Texas Seattle, Washington
WSRCA TPO WEATHERING FARM
Anchorage, Alaska
TEST COMPARISONS FROM REGIONAL LOCATIONS
Las Vegas, Nevada San Antonio, Texas Seattle, Washington
Seattle Fifth Year Inspection and Data Collection
Mechanical Properties Mechanical Properties
• Thickness, Sheet Overall
• Thickness of Coating Over Scrim • Linear Dimensional Change
• Water Absorption • Tensile Properties Chemical Properties Chemical Properties
• Dynamic mechanical analysis (DMA) • Thermogravimetry (TG/DTG)
• Fourier transform infrared spectroscopy (FTIR)
0.000 0.500 1.000 1.500 2.000
SEA1 SEA2 SEA3 SEA4
T h ick n ess ( m m ) 0 0.02 0.04 0.06 0.08 T h ickn ess ( in .) Seattle Seattle Unex p o sed E x p o sed 1-yr E x p o sed 3-yrs E x p o sed 5-yrs 60 mils requested ASTM spec.=1.0mm (0.039in)
60 mils requested ASTM spec.=1.0mm (0.039in)
0.000 0.500 1.000 1.500 2.000
TEX1 TEX2 TEX3 TEX4
T h ic kn ess ( m m ) 0 0.02 0.04 0.06 0.08 T h ickn ess ( in .) Texas Texas Unex p o sed E x p o sed 1-yr E x p o sed 3-yrs 0.000 0.500 1.000 1.500 2.000 LV1 LV2 LV3 LV4 T h ick n ess ( m m ) 0 0.02 0.04 0.06 0.08 Thi c k ne s s ( in. ) Las Vegas Las Vegas Unex p o sed E x p o sed 1-yr E x p o sed 3-yrs
ASTM spec.=1.0mm (0.039in) ASTM spec.=1.0mm (0.039in)
0.000 0.500 1.000 1.500 2.000
AK1 AK2 Ak3 AK4
T h ic k n es s ( m m ) 0 0.02 0.04 0.06 0.08 Thi c k ne s s ( in. ) Alaska Alaska Unex p o sed E x p o sed 1-yr E x p o sed 3-yrs E x p o sed 5-yrs Overall Thickness
Seattle Seattle 0 0.2 0.4 0.6 0.8
SEA1 SEA2 SEA3 SEA4
T h ickn e ss (m m ) 0 0.01 0.02 0.03 T h ickn ess ( in .) Unex p o sed E x p o sed 1-yr E x p o sed 3-yrs E x p o sed 5-yrs 0 0.2 0.4 0.6 0.8
AK1 AK2 Ak3 AK4
Thi c k n e s s ( m m ) 0 0.01 0.02 0.03 Thi c k ne s s ( in. ) Alaska Alaska
ASTM spec.=0.305 mm (0.012in)
0 0.2 0.4 0.6 0.8
TEX1 TEX2 TEX3 TEX4
T h ickn e ss (m m ) 0 0.01 0.02 0.03 T h ickn ess ( in .) Texas Texas Unex p o sed E x p o sed 1-yr E x p o sed 3-yrs 0 0.2 0.4 0.6 0.8 LV1 LV2 LV3 LV4 T h ickn e ss (m m ) 0 0.01 0.02 0.03 T h ickn ess ( in .) Las Vegas Las Vegas Unex p o sed Exposed 1y r Exposed 3y rs
ASTM spec.=0.305 mm (0.012in)
ASTM spec.=0.305 mm (0.012in) ASTM spec.=0.305 mm (0.012in)
Unex p o sed Exposed 1y r Exposed 3y rs Exposed 5y rs
