First Fix vs Second Fix Carpentry: What Is the Difference?

If you are planning an extension, a renovation or a new build, you will hear carpenters and builders talk about first fix and second fix. The terms sound like jargon, but the split is simple: first fix is everything that happens before the plasterboard goes up, and second fix is everything you see and touch once the walls are finished.

What counts as first fix?

First fix carpentry is the structural and hidden work: cut roofs and joists, stud walls and partitions, floorboarding, door linings, window boards where they are built in, and any timber that sits behind the finished surface. It is the skeleton of the job, and it has to be right, because every trade that follows builds on top of it.

What counts as second fix?

Second fix is the finishing carpentry once the plastering and first coats of paint are done: hanging doors, fitting skirting and architrave, boxing in pipework, fitting stair balustrades, and installing kitchens. This is the work you will look at every day, so neat scribes, tight mitres and consistent gaps are what separate a good finish from an average one.

Why the order matters

• First fix has to be square, level and true, or second fix becomes a fight against wonky walls.
• Second fix needs clean, finished surfaces to work to, so rushing the plaster stage costs time later.
• Snagging at each stage is cheaper than opening up finished work to correct a hidden problem.

One carpenter or two?

Plenty of carpenters specialise in one or the other. A carpenter who does both, and treats the hidden first fix with the same care as the visible second fix, will give you a better result, because they know exactly what the finished work needs from the structure beneath it. That is how we work at PRM: the same hands on the roof timbers as on the door handles.

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