EPDM (ethylene propylene diene monomer): synthetic rubber sheet. Thickness: 45 or 60 mil. Width: 10 or 20 ft rolls. Color: black (white available but less common). Installation: fully adhered (contact cement), mechanically attached, or ballasted (10-12 psf river rock). Seams: 3 in min overlap with contact adhesive or seam tape. Flashing: uncured EPDM with adhesive + termination bars. ASTM D4637. FM 4450 approved assemblies. Slope: 1/4 in per ft minimum (can be used at lower slopes with proper drainage). Cost: $4-$8/sf installed. Lifespan: 30-50 years. Advantages: flexibility in cold, UV resistant, easy repair, large sheet sizes minimize seams. Disadvantages: black absorbs heat (higher cooling costs), puncture-prone from foot traffic, adhesive-dependent seams. CSI 07 53 23.