Single-Ply Membranes
EPDM, TPO, and PVC membrane systems - installation methods, seaming, life expectancy, and primer use.
- Describe EPDM membrane properties, seaming methods, and life expectancy
- Explain TPO membrane composition and hot-air welded seams
- Compare thermoset and thermoplastic single-ply membrane characteristics
- Identify the purpose and installation of parapet wall flashing
- Describe the use of primer in single-ply membrane installations
Lesson 1
EPDM Rubber Membranes
What is EPDM
An EPDM roof membrane is a synthetic rubber (ethylene propylene diene monomer) single-ply membrane used for flat and low-slope roofing. EPDM is a thermoset membrane - once vulcanized, it cannot be re-melted or reshaped.
The typical life expectancy of EPDM roofing is 25 to 30 years with proper installation and maintenance. EPDM is available in black and white, in thicknesses of 45 mil and 60 mil for standard applications, and 90 mil for premium installations.
EPDM Installation Methods
EPDM can be installed three ways:
- Fully adhered - bonded to the substrate with contact adhesive
- Mechanically attached - fastened at seams and perimeter
- Ballasted - loose-laid and weighted with stone ballast
EPDM Seaming
EPDM seams are created using seam tape (a cured EPDM splice tape) with primer applied to both surfaces before bonding. The seam area must be cleaned with EPDM splice wash to remove manufacturing release agents.
Primer is Critical
The purpose of primer in flat roofing is to promote adhesion between the membrane and adhesive or tape. Skipping the primer step is the most common cause of EPDM seam failure. Both surfaces must be primed and allowed to become tacky before joining.
EPDM is a synthetic rubber membrane with a 25-30 year life expectancy. Seams are bonded with splice tape and require primer on both surfaces for proper adhesion. EPDM is a thermoset material - it cannot be heat-welded.