There are four of us, and the person who surveys your floor is the person who answers the phone about it. Elena Sobczak has run surveys and scheduling since 2011 — every moisture reading in every job pack is hers, and fitting dates move only when her numbers say so. Josh Tan came from a City & Guilds joinery background and leads the herringbone and border work; the mitred oak border in our gallery is his. Callum Reid is our second-year apprentice, which at Datum means two years of subfloor preparation before anyone lets him near a finished board. Marcus still fits most weeks, still checks every handover with the same straight edge, and still turns down work the readings say should wait.

Wood moves with moisture, and a board fitted the day it arrives is a board fitted at the wrong size. Everything we fit acclimatises on site — stacked and stickered so air reaches every face — for seven days. Measured, not guessed: we log the room the day the stack goes in and fit only when board and room agree within two percentage points. It is the least photogenic part of the job and it is the reason the gaps do not open in January. When a schedule will not allow it, we change the schedule, not the physics.

A hygrometer says what a screed is doing this week; a calcium carbide test says what it will do in February. We run both wherever the first two readings disagree, because the carbide test is slow, destructive and right. Levels are checked with a rotary laser against the room datum — the same datum the fitting is set out from — and the straight edge that signs your floor off at handover is the one that measured the subfloor on day one. None of this is exotic kit. The difference is that the readings are recorded, kept, and handed to you with the invoice.