The 5mm rule: tolerances that separate good from great

Australian building tolerances are forgiving. The NCC and AS standards generally accept reveals of ±5mm on most carpentry work. That's the legal minimum and a lot of builders treat it as the target.

We treat it as the ceiling. Our internal target is ±0.5mm on reveals, ±1mm on overall dimensions for built-in work, ±2mm for structural framing. Here's why.

A 5mm gap between a built-in cabinet and an adjoining wall is invisible to most clients on day one. It becomes visible on day ninety, when they've lived with the piece long enough that the eye starts cataloguing inconsistencies. By month six, that 5mm gap is the only thing they see when they look at the cabinet. By year two, they're sending us a photo and asking if there's a fix.

The fix at year two is expensive (everything has to come out, get re-scribed, get re-installed). The fix at the build stage is twenty extra minutes of careful measurement and a sharper saw cut.

What this costs us: probably 15-20% more labour per job than a "to-code" carpenter. What it earns us: clients who recommend us, who come back for the next room, who don't send month-six photos. Net-positive on the maths over any reasonable timeframe.