Timber keeps exchanging moisture with the air around it. It sits in a truck, then a warehouse, then your half-finished renovation with the heater running, and each of those has different air moisture. Acclimatisation is simply letting the boards adjust to the room they will live in before they are fixed down.
If you skip it, the timber settles at the wrong moisture content and then gets nailed or glued in place. Melbourne’s seasons will still move the floor either way, but a floor laid at the wrong moisture content is far more likely to have a rough first year.
What installers are waiting for
Heating and cooling on. Wet trades done. Relative humidity in a normal occupied range. A closed-up damp shell doesn’t qualify, and neither does an empty house with ducted heating running flat out and no furniture or curtains yet.
Practical site checks before packs open:
- Concrete slabs cured and within the moisture limits the adhesive and system allow. Ask the layer to test it properly; judging by feel isn’t reliable.
- Plaster and paint mostly finished, so the big water loads are out of the air.
- Windows in, building weathertight.
- HVAC or heating running at something like lived-in settings for a stretch, often several days. One cold morning with the heater on full doesn’t count.
Open packs only when the site is ready. Boards stacked in a wet garage will settle at the wrong moisture content. Leave the plastic on until the room is ready, then acclimatise per the manufacturer, which is often several days to about 1–2 weeks (many sheets specify around 3–7 days once opened, longer if mill and site moisture are far apart). Follow the pack insert, even if a mate swears by a shortcut.
Solid vs engineered
Solid strip moves more in width, so it is more sensitive to acclimatisation and needs a proper expansion gap. Engineered moves less but still isn’t immune, especially cheaper or thinner builds, or wide planks.
Hybrid isn’t hygroscopic in the same way; its usual problems are temperature and subfloor flatness. See timber vs hybrid vs laminate.
The short version of the process:
- Get the room to lived-in climate.
- Deliver and keep sealed until that point.
- Open and stack or rack as the manufacturer says, with airflow around the packs; one sealed cube in a corner doesn’t count.
- Measure moisture if the installer is doing it properly, on both board and subfloor.
- Lay only when both are in the allowed window.
- Leave expansion gaps and cover them with trims or skirting later. Don’t fill the gap with silicone to tidy it up.
Melbourne quirks
In winter, heaters dry the air, and boards that soaked up site moisture before install shrink afterwards. Hairline gaps show up in July on a floor that looked tight in March. Summer humidity and storm weeks can push the other way, when boards take up moisture and need room to grow.
Timing the install for a stable week helps. So does not laying into a building that is still curing concrete or drying fresh plaster, with all that water in the air. Empty new builds with temporary heaters are a common trap: the timber acclimatises to very dry air, then the family moves in, cooks, showers and hangs washing, humidity rises, and the floor reacts.
Expect some seasonal movement afterwards regardless. See what to expect from solid timber. Acclimatisation reduces the shock; it doesn’t stop timber moving with the seasons.
Typical ranges
- Many manufacturers specify days rather than hours, often several days to about 1–2 weeks depending on the product. Plenty of sheets land around 3–7 days once packs are opened. Follow the insert.
- Occupied timber floors are often discussed around 40–60% RH; blast-heated empty sites and damp shells sit outside that.
- Expansion gaps at walls are commonly 8–15 mm depending on span, species and system, with the installer setting the detail.
If the quote skips moisture testing on a slab job, ask why. For joists vs slab, start at how to choose timber flooring.