The Five Key Trades on a Building Site, and Where the Plumber Fits

Five trades is the easy part. The part nobody writes down is the order they work in, and what happens to everybody else when one of them is late.

The short answer

Five trades: electrician, plumber, carpenter, bricklayer, plasterer. The plumber does hot and cold water supply, central heating, bathroom installation, and sanitation and drainage — the widest list of the five.

That is the exam answer, and our Level 1 lesson covers it properly. What follows is the part that only makes sense once you have stood on a site.

First fix and second fix

Almost every trade splits its work in two, and the words come up constantly.

First fix is everything that goes in while the walls and floors are still open — your pipework, the electrician's cable, the carpenter's structural timber. It gets buried.

Second fix is everything that goes on afterwards, once the plasterer has been and the decorator is nearly done — taps, radiators, sanitaryware, sockets, switches, door furniture.

Between the two sits the plasterer, and that is the pinch point of the whole job. Anything you did not do at first fix means cutting a finished wall open at second fix, which is somebody else's work destroyed and somebody else's argument.

The order, and who waits for whom

Roughly, on a new build:

• Groundworkers and the bricklayer put up the shell.
• The carpenter puts the roof on and the floors in.
• The roof goes on and the building becomes watertight — which is the moment the inside trades can start.
• Plumber and electrician first fix, working around each other in the same walls and floors.
• The plasterer closes it all up.
• Plumber and electrician second fix, then the decorator.

What that means in practice: you are never working alone, and you are almost never working at your own pace. If the roof is late, your first fix is late. If your first fix is late, the plasterer is late, and so is everybody after them. Programme pressure on a plumber usually comes from something that happened three trades ago.

Getting on with the other trades is part of the job

This sounds like advice about manners. It is not — it is about not having your work ruined.

The carpenter needs to know where your pipes run before they board a floor, or a nail goes through a pipe and nobody finds out until the system is filled. Mark your runs. The electrician wants the same courtesy from you, because a hole drilled blind through a stud finds cable just as easily as a nail finds pipe.

The plasterer will cover anything you leave, including a joint you meant to come back to. Get your first fix signed off before it disappears.

And the bricklayer builds the wall you are going to want a hole in. Ask early, and it gets built in. Ask late, and you are core drilling.

Where the plumber sits in all of this

Look at the four jobs the standard gives the plumber against two or three for everyone else. That width is the trade. It is also why a domestic plumber's week is genuinely varied — a bathroom, then a boiler, then a drain — and why the qualification takes longer than people expect.

It is worth knowing that the wide list narrows later if you want it to. Heating engineers, drainage specialists, industrial plumbers and maintenance engineers are all plumbers who chose one part of it. You do not have to decide now, and most people decide by accident, based on who employs them first.

What comes next

At Level 2 the same trades come back, but the questions change from "who does what" to "how does your work interact with theirs" — notching and drilling joists to the permitted zones, working around electrical safe zones, and who signs off what. The joins between trades stop being a fact to learn and start being a set of rules with numbers attached.