Choosing Pipe Material — PPR, PEX, uPVC, and Cast Iron
Pipe material is an estimating decision with a long tail — it sets the fittings, the labour method, and the failure modes for the life of the building.
Match material to service
| Material | Best for | Max temp | Jointing |
|---|---|---|---|
| PPR | Hot & cold pressurised supply | ~70 °C continuous | Heat fusion (socket weld) |
| PEX | Concealed hot & cold, radiant loops | ~60–70 °C | Crimp / press / expansion fittings |
| uPVC | Cold supply, drainage, vent | ~40 °C (supply) | Solvent cement |
| CPVC | Hot & cold supply | ~80 °C | Solvent cement |
| Cast iron | Drainage, stacks (acoustic, fire) | n/a | Hubless couplings / caulked |
Pressure vs gravity
Supply pipe carries pressure and must be rated for the system pressure plus surge (PN rating). Drainage and vent pipe carries no pressure — wall thickness is chosen for handling and slope stability, not hoop stress.
Estimating implications
- PPR needs a fusion tool and trained labour; fittings are relatively costly but joints are permanent and leak-free.
- uPVC is cheap and fast with solvent cement, but expansion and UV exposure need managing on exposed runs.
- PEX reduces fittings dramatically on home-run manifold layouts — fewer joints buried in walls.
- Cast iron costs more in material and labour but is specified where drainage noise transmission or a fire-rated shaft matters.
Standards to cite
Reference the product standard in the BOQ (e.g. ISO 15874 for PPR, ISO 15875 for PEX, ISO 1452 for uPVC pressure, ISO 3633 for uPVC soil and waste) so bidders price an equivalent product.
EngEst Pro lets you set the pipe material per system, and the Plumbing Calculator generates the matching fittings, jointing consumables, and supports in the BOM — switch material and the quantities and prices update.
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