What is pex pipework?
Pex pipework is Cross-linked polyethylene tubing. It is a plastic material used to run water and gas as an alternative to copper or galvanised steel piping systems.
Why can it not be exposed to sunlight?
Pex piping can be used internally and is compliant when not exposed to sunlight. However, pex is highly susceptible to damage by sunlight. If exposed to sunlight, the molecular structure will begin to disintegrate. External gas lines run in pex will lose integrity over time and will no longer be able to safely carry gas.
What can happen if exposed Pex is not addressed?
When Pex is exposed to UV for an extended period of time, the outer layer of Pex plastic progressively degrades. Eventually, it goes a chalky white and small visible cracks appear. This degradation process eventually exposes the inner aluminium core which then itself corrodes. Eventually, this leads to failure of the gas piping system. See the example photo below.