What Is First Fix and Second Fix?

First fix is the work carried out before walls and floors are closed up: cables, pipes, framing and structure. Second fix is everything installed afterwards, once plastering is done, sockets, radiators, doors, sanitaryware.

Why the distinction matters

It divides almost every project into two halves with plastering between them, which makes both natural payment stages. First fix complete is something you can inspect before it disappears behind plaster. Second fix complete is close to finished.

If a builder proposes payment stages, expect these two to appear. If they do not, ask why.

What sits in each

First fix: stud walls, joists, cable runs, pipework, back boxes, waste pipes, window frames.

Second fix: sockets and switches, light fittings, radiators, taps and sanitaryware, doors and handles, skirting and architrave.

Inspecting first fix

This is the moment to look. Once plastered, changes mean cutting the wall open again. Take photographs of cable and pipe routes before they are covered, it is genuinely useful years later when someone drills a wall.