Membrane Roofs (EPDM or TPO/PVC) – Heating them, life expectancy and options
EPDM is Ethylene Propylene Diene Monomer. EPDM roofs are singly ply membranes (one ply of roofing material, not multiple laminated layers). Since the 1960’s EPDM roofs have been used in the United States and is a quite common roofing material for low slope roofs. Simply a rubber material – EPDM is a flexible rubber matrix that is formed from a chemical reaction when Diene is added to the Ethylene and Propylene mix. EPDM can be reinforced or un reinforced, vulcanized or non-vulcanized (chemical process for converting rubber or related polymers into more durable materials via the addition of sulfur or other curatives or accelerators) – vulcanization on Wikipedia.
Thicknesses range from thirty mils (0.030″) to one hundred mils (0.100″). A common thickness for roofing is forty five mils (0.045″) or sixty mils (0.060″). EPDM roofs can be adhered with adhesive, mechanically fastened, or floated(loose laid). Adhered EPDM uses water or solvent based adhesives, mechanically fastened EPDM uses fasteners, floated or loose laid is only fastened around the edges and penetrations(typically these roofs are underlayments for rock, pavers etc, something that will hold it down around the perimeter or the entire surface).
When installing multiple EPDM sections, adhesive or tape is used to seal seams. In terms of longevity, EPDM roofs last anywhere from 12 to 25 years, depending on the mil, type, and attachment method used.
TPO/PVC Membranes are another type that can be installed over our roof deicing elements. These membranes are thermoplastic materials with no chemical crosslinking. These membranes can be repeatedly softened by heating or hardened when cooled. PVC and TPO membranes can be installed by adhering, mechanically attaching, or ballasting. Seams are heated or chemically welded together. These membranes typically have the same life expectancy as EPDM membranes.
Heatizon ZMesh or Tuff Cable in Invizimelt or Heatsink systems can be installed under EPDM or TPO/PVC roofs easily. ZMesh or Tuff Cable systems can be adhered to an existing membrane(if there is one) while another is attached on top. If there is a subroof below and no existing membrane and penetrations are not a concern, ZMesh can be nailed or stapled down into non-conductive surfaces, Tuff Cable heatsink or Invizimelt systems can also me nailed down to the subdeck or subroof. Membranes are then installed on top of these systems creating a long lasting invizible heated roof surface that could extend the life of the EPDM roof allowing drainage since drainage is a large factor in the life expectancy of membrane roofs. See more about our roof deicing solutions here
The image on the right is ZMesh installed under a TPO membrane for deicing and drainage