Commercial Roofing in Philadelphia: TPO vs EPDM vs Modified Bitumen (What to Choose)

Commercial roofs typically feature:

• Larger low-slope surface areas
• More penetrations (HVAC units, vents, skylights, exhaust fans)
• Higher foot traffic from maintenance personnel

These factors make installation details and ongoing maintenance plans more critical than brand marketing claims.

TPO (Thermoplastic Polyolefin) is widely used on commercial roofs because seams are heat-welded, creating strong bonds. It performs well when installed by experienced crews.

Key questions to ask:

• How are seams tested after welding?
• How are terminations handled at parapets and around penetrations?
• What does the warranty cover, and what's excluded?

EPDM (Ethylene Propylene Diene Monomer) has decades of proven performance and can be extremely durable in the right applications.

The primary risk is sloppy detailing at seams, edges, and penetrations. Ask specifically how the contractor handles edge metal installation and membrane terminations.

Modified bitumen excels on roofs with numerous details and penetrations. It's typically thicker and more puncture-resistant than single-ply alternatives.

Ask whether the installation method is torch-applied or cold-applied, and how fire safety protocols are managed for torch-down applications. Both methods can be appropriate depending on the situation.

For any commercial roof, drainage design is the most critical factor.

Ask the contractor to identify:

• All drain locations and their condition
• Known low spots and ponding areas
• Whether tapered insulation will be used to improve positive drainage

If a contractor cannot clearly explain the drainage strategy, continue evaluating other options.