If PEX is to be buried under a building, what must not be used?

When PEX piping is installed underground or under a building, it is essential to avoid using fittings. Fittings can introduce points of potential failure due to changes in direction, which can lead to leaks, especially when buried where access for repairs is limited. In contrast, connectors, adapters, and joints are components that may be necessary for specific applications or connections within the PEX system, but as long as they meet the specifications for burial and water-tight performance, they can be acceptable.

Buried installations require careful consideration, and PEX itself is designed for flexibility and resistance to freezing. However, the use of fittings can compromise this integrity in an underground setting, since they may not have the same thermal expansion characteristics as the PEX itself and could suffer from stress over time due to soil movement, settling, or temperature fluctuations. Therefore, avoiding fittings in buried installations helps ensure the longevity and reliability of the piping system.