SINGLE-PLIES Because PVC is thermoplastic, it can be melted and fused by heat using a hand-held, hot-air welder (above) or an automatic welder (left). The seam is theoretically as strong as the membrane. EPDM, the most common and least expensive single ply, has excellent strength, durability, and flexibility across a broad range of temperatures. FOR SMALL JOBS Sorting through the array of single-ply roofing options by Michael Russo In the last 10 years, the market share of single-ply systems has increased from 3 or 4 percent to over 50 percent of the commercial roofing market. Single plies have proved they are cost-effective, high-performance alternatives to builtup roofing (BUR), and can provide similar benefits in low-slope residential applications. One of the primary reasons for the success of these systems
