Single Ply Membranes 

Single Ply Membranes

     Ethylene Propylene Diene Monomer (EPDM) or "Rubber" EPDM materials have been used as a roofing material here in the United States since the early 1960's.  EPDM is a synthetic rubber material that is formulated with extensive flexibility for use as a membrane sheet roofing.  EPDM is manufactured as a vulcanized (cured) membrane.  Uncured EPDM is manufactured for use as a flashing material.  EPDM can only be bonded to like material with an adhesive when making seams.  This adhesive can be seam tape and some liquid adhesives.  EPDM membranes range in thickness of .045mils to .120mils.  Only fully cured EPDM will bond together creating a molecular linkage.  EPDM membranes exhibit good resistance to ozone, UV rays, weathering, and abrasions.  EPDM has good low temperature flexibility.  EPDM is resistant to some acids and solvents.  On the other hand exposure to animal fats, vegetable oil and petroleum based products should be avoided.

Thermoplastic Roof Membranes (including PVC membranes and TPO membranes)

     Polyvinyl Chloride (PVC) polymers were originally produced in Germany during the 1950's.  The basic chemical resin is a relatively hard material that requires the addition of plasticizers to make it supple and pliable for use as flexible membrane roofing.  PVC sheets are reported to be resistant to bacterial growth, many industrial chemicals and plant root penetration.  PVC roof membranes are fire resistant and have good seaming characteristics.  PVC is not chemically compatible with bituminous materials.

     TPO roof membranes are compounded from a blend of polypropylene and ethylene-propylene rubber polymers.  TPO membranes exhibit positive physical properties, such as heat aging, cold temperature flexibility, puncture resistance and tear strength.  They are resistant to damage from animal fats, hydrocarbon oils, and vegetable oils.  They will not support the growth of microorganisms.

     A summary of Thermoplastic Roof membrane characteristics, both chemical and physical, materials allow them to be repeatedly soften when heated and harden when cooled.  Typically there is no chemical cross-linking in the membranes compound.  Because of the nature of the membrane, Thermoplastic sheets typically are seamed by heat-welding with hot air.

Key Points

     EPDM has tried in the industry to eliminate manual "applicators" of glue, solvents, new designs are on going to take the human factor out of the waterproofing procedure.  This goes with seam tape, seam flashing, and pre-molded parts - all for ease of application.  Many different manufacturers have different formations in the EPDM manufacturer process to help eliminate shrinkage, thin spots, race tracking, etc.

     Whatever single ply roof is chosen; all surfaces are not good candidates for this type of roof.  Very important considerations should be given such as foot traffic, mechanically equipment maintenance, roof heights, and many more.  Please give considerations to all in making a selection.