First fix and second fix joinery: what the terms actually mean
Builders talk about first fix and second fix as if everyone knows the difference. Here is what each stage covers and why the order matters.
The simple rule
First fix is everything that goes in before the walls are plastered. Second fix is everything that goes on afterwards, once the plaster is dry and decoration is underway. The split runs right through a build — joinery, plumbing and electrics all have a first and second fix.
What first fix covers
First fix joinery is the structural and hidden carpentry — the timber that other trades build around.
- Door linings and window frames fixed into openings
- Floor joists and roof timbers trimmed and fixed
- Stud partition walls framed up
- Timber lintels, noggins and fixings for what comes later
What second fix covers
Second fix is the visible, finishing carpentry that happens after plaster.
- Hanging doors and fitting ironmongery
- Skirting, architrave and trim
- Fitting windows, stairs parts and built-in joinery
- The clean, flush finishes people actually see
Why the order matters
First fix has to be set out precisely because everything after it references those positions. A frame a few millimetres out of square shows up once the door is hung and the architrave goes on. Getting measurements right at first fix is what makes second fix quick and clean.
Related questions
Do you do both first and second fix joinery?
Yes — first and second fix carpentry, from door frames and timber work during the structural stage through to hanging doors, skirting and finishes once plaster is done.
Can joinery be coordinated with structural steelwork?
Yes, and it should be. First fix timber often goes in alongside the steels, so taking the measurements together means the joinery and structural work fit without gaps or awkward adjustments.
Ready to take it further? See our joinery — 1st & 2nd fix service.