Q: Will PEX pipe break if it freezes?
A: No, PEX pipe is freeze-damage resistant, meaning the pipe will expand if frozen and contract to its original shape when thawed. PEX pipe is not freeze-proof, however, meaning that the water in the pipe can still freeze and block the flow.
You should use the same standard insulation precautions with PEX pipe to help prevent freezing. PEX pipe should not be used outdoors in direct sunlight because it is not approved for continuous UV exposure.