First fix and second fix are terms used in the UK and Irish housebuilding and commercial building construction industry.
First fix comprises all the work needed to take a building from foundation to putting plaster on the internal walls. This includes constructing walls, floors and ceilings, and inserting cables for electrical supply and pipes for water supply.
Some argue that First Fix starts after the shell of the building is complete, and ends when the walls are plastered. Here is a list, in no particular order, of the elements of First Fix.
Drain runs: must be downhill and straight
Spare conduits: draw strings
Soil pipes
Copper pipes
MVHR (mechanical heat recovery ventilation runs)
Push-fit or other plastic piping
Electrical back boxes
Electricity cable runs
Telephone, data and audiovisual cables
Socket location
Security
Fire alarm
Normal pipes
Door bell
Door frames
Pocket doorframes
Stair well: floating / cantilevered?
Sound insulation
Plasterboarding
The list is not exhaustive.
Second fix comprises all the work after the plastering of a finished house. Electrical fixtures are connected to the cables, sinks and baths connected to the pipes, and doors fitted into doorframes. Second fix work requires a neater finish than first fix.
The division of work is a convenient description because electricians, plumbers and carpenters will probably have to make two separate visits to one property under construction, at separate times. Project managers can report "first fix complete" or "second fix 50% done" and others can understand.
Some construction companies specialise in first fix work or second fix work, but most do both.
In North America, terms such as roughing in and finishing or rough-in and finish work are often heard, referring to similar concepts. Another related set of terms is outside work and inside work (the building is closed to the weather when the latter occurs). Carpenters speak of rough work and trim work (or framing versus trimming), and other fields have analogues, such as machining (roughing versus finishing cuts) and communications (rough draft versus revised draft).
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