When comparing these two systems, torch-on (modified bitumen) offers superior puncture resistance compared to TPO.

According to the provided comparison data:

• Torch-on (Modified Bitumen): This system provides high puncture resistance. It is a robust material reinforced with either a fiberglass or polyester mat, making it highly durable against physical damage and heavy snow loads.
• TPO (Thermoplastic Polyolefin): This system provides moderate puncture resistance. While it is reinforced with a scrim to improve its tear strength, it is generally more susceptible to punctures than the heavier two-ply construction of a modified bitumen system.

Both systems are considered reliable flat roofing options for the Lower Mainland, but torch-on is specifically noted for its superior ability to withstand physical impacts.