What is first fix and second fix in construction?

First fix is everything that happens before the walls are plastered. It covers the structural and hidden work — stud walls, floor joists, roof timbers, window and door frames (or linings), pipe runs for plumbing and heating, and electrical cable runs with back boxes for sockets and switches. None of this work is visible once the house is finished, but it forms the skeleton that everything else is built on. First fix is the most labour-intensive stage and typically accounts for 40 to 50 percent of the total build cost on a new-build or extension.

Second fix is everything that happens after plastering. It is the finishing stage — fitting sockets, light switches, and light fittings onto the cables run during first fix. For plumbing, second fix means connecting taps, toilets, basins, radiators, and the boiler. For carpentry, it means hanging doors, fitting skirting boards, architrave, and built-in storage. Second fix is where the house starts to look like a home. It requires precision and a good eye for detail because everything is visible. A poorly fitted skirting board or a socket that is not level will be noticed every day.

When reviewing a quote, check that both stages are clearly listed and priced. Some builders lump everything together, which makes it hard to track costs. A well-structured quote will show first fix carpentry, first fix electrics, and first fix plumbing as separate line items, then the same for second fix. This also helps if you are managing separate trades yourself rather than using a main contractor. The plasterer comes in between first and second fix, so scheduling depends on getting this sequence right. TailoredQuote generates quotes with this level of breakdown automatically.