Materials
and pipework
Copper or plastic. Solder or compression. Solvent weld or push-fit. Every one of those decisions changes what a job costs, how long it takes and whether it leaks in five years. This unit covers the materials you will handle every week and the jointing methods that go with them — then lets you price a pipe run yourself.
What pipe is made of
Five materials, five jobs| Material | Used for | Sizes | Why you would pick it |
|---|---|---|---|
| Copper BS EN 1057 |
Hot and cold supply, heating | 15 / 22 / 28 mm | Rigid, takes heat, holds its shape, looks right where it is on show, and lasts fifty years or more. Sold in 2 m and 3 m lengths — use 3 m where you can, because fewer joints means fewer leaks. |
| Plastic push-fit PB or PEX, barrier pipe |
Hot and cold supply, heating | 10 / 15 / 22 / 28 mm | Fast, no flame, bends round obstacles and tolerates a little freezing without splitting. Needs a pipe insert in every cut end and far more clips than copper. |
| MDPE blue, underground |
Incoming water main | 20 / 25 / 32 mm | The blue coil that runs from the boundary into the house. It is blue specifically so anyone digging knows it is drinking water. |
| PVC-u / ABS waste | Above-ground waste | 32 / 40 / 50 mm | Light, cheap, joins by solvent weld or push-fit ring seal. Different plastics need different solvent cements — check before you glue. |
| PVC-u soil | WCs and the stack | 110 mm | The big one. Push-fit with a rubber seal, which also lets it expand and contract without cracking. |
Supply pipe is named by its outside diameter, so 15 mm copper measures 15 mm across the outside and about 13.6 mm inside. Waste pipe is also named by outside diameter, but the imperial and metric ranges are not interchangeable — an old 1½ inch waste is not the same as 40 mm, and forcing the two together is a classic way to create a slow leak inside a cupboard.
Five ways to join a pipe
And when each one is right| Method | Flame? | Can be undone | Fitting cost | Where it belongs |
|---|---|---|---|---|
| Compression | No | Yes | £1.50 – £4.00 | Accessible places — under a sink, at an appliance, anywhere you may need to break the joint later. |
| Solder ring Yorkshire | Yes | No | £0.80 – £2.00 | Neat permanent work on show. The solder is already in the fitting, so it is quick and consistent. |
| End feed | Yes | No | £0.30 – £1.00 | High-volume first fix. Cheapest fitting there is, but you feed the solder yourself, so it rewards practice. |
| Push-fit | No | Yes | £2.00 – £5.00 | Speed, awkward corners, and anywhere a flame is a bad idea — a loft full of insulation, a floor full of joists. |
| Press | No | No | £4.00 + | Commercial work. A battery tool crimps the fitting in two seconds. The tool costs four figures, which is why you rarely see it on domestic. |
The rule that matters more than the method. Never bury a joint that can be undone. Compression and push-fit joints are designed to be accessible; put one under a screed floor or behind a tiled wall and you have built a leak you cannot reach. Buried and inaccessible runs should be unbroken pipe, or soldered.
Which joint would you use?
Six real situationsPick a situation and see what an experienced plumber would reach for, and why.
Holding it up
Clip spacingUnsupported pipe sags, rattles and eventually leaks at the joints. Plastic needs far more support than copper because it is flexible — a plastic run clipped like copper will look like a hammock by the second winter.
| Pipe | Horizontal | Vertical |
|---|---|---|
| Copper 15 mm | 1.2 m | 1.8 m |
| Copper 22 mm | 1.8 m | 2.4 m |
| Copper 28 mm | 1.8 m | 2.4 m |
| Plastic 15 mm | 0.3 m | 0.5 m |
| Plastic 22 mm | 0.5 m | 0.8 m |
Expansion
Hot pipe grows. A long straight heating run needs somewhere to take that movement, or it will tick and creak every time the boiler fires. Leave it slightly loose through joists and never clamp it rigid at both ends of a long run.
Insulation
Any pipe in a loft, a garage or an unheated void gets lagged — not to save energy, but to stop it freezing and splitting. It is the cheapest thing on the van and the most expensive thing to leave off.
Price a pipe run
Materials only — labour comes in Unit 06Set up a run and watch the material cost move. Change the jointing method and you will see why the choice is not only a technical one. Prices are typical merchant figures for 2026.
Slide to 0 to price the run without clips and see what you would be leaving off.
Sundries covers solder, flux, PTFE, jointing compound and pipe inserts — small money individually, but it is on every job and it is the first thing people forget to price.
Check what you have taken in
10 marksA 15 mm run has to be chased into a wall and plastered over. Which jointing approach is right?
What is the pipe insert for, in a plastic push-fit joint?
An 8.4 m horizontal run of 15 mm copper is clipped at the maximum permitted spacing. How many clip intervals are there along the run?
Price the materials for a 14 m run of 15 mm copper with 10 solder ring fittings at £1.40 each. Pipe is £3.50 per metre. Ignore clips and sundries, but add 10% for waste. Give your answer to the nearest pound.
Produced for EAL Learn+.
Introduction to Plumbing — a 30-hour pre-apprenticeship short course.