What do first fix and second fix actually mean?

The terms come up in every quote and every conversation on site, and nobody explains them, which matters because the boundary between the two is the most consequential moment in a renovation. Understanding what is happening on either side of it tells you when your decisions are due and why lateness costs so much.

Step by step

1. Understand what first fix covers.Electrical cables pulled to every socket, switch, light and appliance position; water pipes and waste runs; heating pipework and radiator tails; drainage; data and aerial cable; and the studwork, noggins and battens that later fixings need.
2. Understand why first fix fixes the layout.Every position is decided here. A socket added after plastering means chasing out finished plaster, replastering, redecorating — a job that took ten minutes at first fix and takes half a day afterwards.
3. Have the awkward items decided before it starts.Kitchen layout and appliances, bathroom layout and sanitaryware, television and desk positions, outside taps and sockets, underfloor heating zones. First fix cannot be done properly against an undecided kitchen.
4. Insist on noggins for anything heavy.Wall-hung televisions, basins, radiators, handrails, kitchen wall units. Timber behind the plasterboard, in the right place, costs almost nothing now and is impossible later without opening the wall.
5. Photograph everything before it is covered.Every wall and floor with pipe and cable runs visible, with something in shot for scale. This is the only truly reliable record of where the services are, and it is worth more than any detector in five years' time.
6. Get the inspections done before covering up.Building control at the stages agreed, and the electrician's own inspection and testing. Plasterboard over uninspected first fix is the mistake that gets opened back up.
7. Understand the middle stage.Plastering and screeding, then drying. Plaster needs weeks rather than days before it is painted, and painting damp plaster means doing it twice. Build the drying time into the programme rather than discovering it.
8. Understand what second fix covers.Sockets, switches and light fittings; radiators hung on the tails; taps, sanitaryware and the boiler connected; doors, architraves and skirting; kitchen units and worktops. Everything that meets a finished surface.
9. Know what comes after second fix.Decoration, then flooring, in that order. Paint on an unfinished floor costs nothing; paint on a new floor costs a floor.

Tips

• Ask for a first fix walk-round before anything is boarded. Standing in the room with the cables visible is the last easy chance to notice that a socket is behind where the sofa goes.
• Mark the positions on the floor with tape before first fix — furniture, appliances, the bed. It is far easier to judge than a drawing.
• Every trade has a first and second fix, not just the electrician. Plumbing, heating, joinery and data all split the same way.

Common mistakes

• Choosing the kitchen after first fix — Pipe and cable positions depend on the actual units and appliances. Choosing afterwards means either moving services or accepting a compromise you will look at every day.
• Boarding over first fix before it is inspected — Building control and the electrician both need to see the work. Covering it early means opening it up again at your cost.

Questions people ask