Quick Facts  -   Single Ply Roofing Systems

 

bulletThe three major Single Ply Roofing systems are: PVC, TPO, & EPDM
bulletDivided into two categories: weldable and non-weldable.
bulletPVC (Poly Vinyl Chloride) Weldable.  Developed in the late 1970's in Europe.  Good fire resistance.  Needs plasticizer for flexibility.  Typical thickness is either 47 mils or 60 mils.
bulletTPO (ThermoPlastic Olefin) Weldable.  Polypropolyene with ethylene proprolyene rubber mixed in to make flexible - no plasticizers.  No natural fire resistance.  Developed in the 1990's.  Typical thickness is either 45 or 60 mils.
bulletEPDM (Ethylene Propylene Diene Monomer) Non-Weldable.  Developed in the 1960's in the United States.  Very large sheets.  Good Chemical resistane, poor oil, grease and asphalt resistance.  Typical thickness is 45, 60, 75, 90 mils. 
bulletThree Types of Single Ply Installation: Mechanically Attached, Ballasted, Fully-Adhered.
bulletMechanically Attached: Use rows of fasteners to hold roof down.  If not in laps then cover strips are needed.  Reinforced sheet recommended.
bulletBallasted: Typically #3 or #4 river washed (rounded) gravel at 10-12 pounds per square foot.  Requires solid perimeter attachment.  Not recommended for high wind areas.
bulletFully adhered: Typically contact cement is used to adhere membrane to substrate.  Foam and bitumen have been used with fleece backd membranes.  Substrate must be approved by membrane supplier.

 

Mechanically Attached

 Ballasted Fully Adhered
Advantages Disadvantages Advantages Disadvantages Advantages Disadvantages
bulletGood wind uplift resistance
bulletPoorer Performance History
bulletEconomical to install
bulletWeight of ballast
bulletGood wind uplift resistance
bulletCost
bulletLower cost than fully adhered
bulletMore Stress on Seams
bulletInstalls fast
bulletDifficult to inspect
bulletEase of inspection and leak finding
  
bulletEase of inspection and leak finding
bulletNot Practical on concrete and lightweight insulating concrete
bulletGood weather, abuse, and fire resistance
bulletLimited amount of good ballast
bulletWorks well on unique roofs
  
 
bulletDifficult to use with vapor retarders
        
           

Source:  The Roofing Industry Educational Institute