What is acclimatisation?
Acclimatisation is the process of bringing timber flooring to – or close to – the moisture content it will settle at in the finished building, before it is installed. The target is the in-service equilibrium moisture content (EMC): the moisture level at which timber stops gaining or losing water to the surrounding air.
Get it right and the floor stays tight and flat. Get it wrong and boards shrink (gaps) or swell (cupping, peaking or lifting) after installation – problems that are hard to fix once parquet is glued and finished.
The ±2% rule
Install timber flooring within about ±2% of the EMC it will reach in service (WoodSolutions). For example, if a home is expected to sit at around 10% EMC, boards between roughly 8% and 12% are within the target; outside that, the risk of movement problems climbs.
That makes acclimatisation a moisture target, not a number of days. Some timber arrives close to the target and needs little time; other timber needs longer, especially when the site and the supply chain have very different conditions.
EMC: what the numbers say
Timber's EMC rises as relative humidity rises – ATFA gives about 11% EMC at 25°C and 60% RH, and about 16% at 80% RH. Typical Australian interiors sit between about 8% and 14%.
| Condition | EMC (approx.) | Source |
|---|---|---|
| 25°C, 60% relative humidity | ~11% | ATFA |
| 80% relative humidity | ~16% | ATFA |
| Typical Australian interiors | ~8–14% | WoodSolutions |
| Australian-made boards at supply (average) | ~10–12% MC | ATFA specification |
For local EMC targets, NATSPEC's technical note on moisture content in timber floors is a useful reference for specifiers (NATSPEC DES 002).
Climate examples
Humid, coastal and tropical climates push the in-service EMC toward the upper end of the range; dry inland climates and heavily heated or air-conditioned homes push it toward the lower end. The table shows the direction of travel – your installer's measurements set the actual target.
| Situation | Likely in-service EMC | What it means for acclimatisation |
|---|---|---|
| Humid coastal or subtropical (e.g. Brisbane, Gold Coast, Auckland) | Toward the upper end of the range | Drier boards may take up moisture – check before laying |
| Temperate (e.g. Melbourne, Adelaide, Wellington) | Mid-range, with seasonal swing | Install for the average, not a dry spell or a wet week |
| Dry inland or alpine (e.g. Canberra in winter, Queenstown) | Toward the lower end, especially with heating | Wetter boards may shrink – allow time and measure |
| Air-conditioned apartment | Lower than outdoor air suggests | Run the HVAC as normal during acclimatisation |
| New build with wet trades or a damp slab | Temporarily high | Don't acclimatise until the building has dried |
Seasonal swings matter too: a floor laid at the end of a humid summer will see drier air in winter, and vice versa.
How to acclimatise oak flooring: step by step
Prepare the site first, then measure the timber and the site, and lay only when they're within about ±2%.
- Finish wet trades. Plastering, painting, tiling and screeding add moisture. Wait until they're done and dry.
- Close in and condition the building. Windows and doors in, and heating or cooling running as it will in normal use.
- Test the subfloor. Slab moisture has its own limits, set by the adhesive maker – see installing parquet over a concrete slab.
- Deliver and store correctly. Store boxes flat, off the slab, away from external doors and direct sun, in the rooms where they'll be laid.
- Follow the supplier's instructions on opening packs. Some products should stay sealed until laying; others are opened and spread out. Ask Timbo for the instructions for your batch.
- Measure board moisture content on a sample of boards from several boxes with a meter set for oak – see moisture content in timber flooring.
- Measure or estimate the in-service EMC from indoor temperature and humidity readings over several days.
- Lay when within about ±2%. Record readings and dates in the job file.
Storage on site
How parquet is stored on site matters as much as how long it's there.
| Do | Don't |
|---|---|
| Store boxes flat on bearers, off the slab | Stack directly on a new slab |
| Keep them in the rooms where they'll be laid | Leave them in a garage, shipping container or outdoors |
| Keep away from external doors, windows and direct sun | Store next to heaters or air-conditioning outlets |
| Keep wrapping intact until the instructions say to open | Open boxes while plastering or painting is under way |
| Protect from other trades' traffic and spills | Use boxes as a workbench |
When delivery is booked, make sure the site is ready to receive the timber – see delivery and lead times for how Timbo handles freight.
Acclimatisation checklist for installers
- Site enclosed, wet trades finished, HVAC running as normal
- Slab tested and within the adhesive maker's limit – in NZ, see the NZ slab guide
- Board moisture readings recorded from several boxes
- Indoor temperature and humidity recorded over several days
- Boards within about ±2% of the expected in-service EMC
- Batch number recorded and boxes blended during laying
Acclimatising solid oak parquet
Solid oak parquet blocks are short, so each block moves less in absolute terms than a long board – but there are hundreds of joints per room, and a whole glued floor still moves as a unit. That's why moisture control and correct expansion allowances matter just as much for parquet as for boards.
Timbo does not publish a dispatch moisture content figure on this website. Measure the blocks on arrival and compare with site conditions; your Timbo partner or Timbo can advise on the batch.
Underfloor heating and acclimatisation
With underfloor heating, the heating system is commissioned and run before installation so the slab is dry and the timber acclimatises to heated conditions. Follow the heating system's and adhesive maker's protocol. See underfloor heating and oak flooring.
Sources
- ATFA (floorchoices.com.au) – Acclimatisation of timber flooring
- WoodSolutions – Moisture guide
- ATFA – Specification for solid timber flooring
- NATSPEC TECHnote DES 002 – Moisture content in timber floors
Frequently asked questions
How many days should oak flooring acclimatise before installation?
There is no universal number of days. Acclimatisation is complete when the boards are within about ±2% of the moisture content they'll reach in service. Some timber arrives already close and needs little time; some needs longer. Measure, and follow the manufacturer's and adhesive maker's instructions.
Should I open the boxes to acclimatise parquet?
Only when the site is ready. Opening boxes in a building with wet plaster, a damp slab or no climate control lets the timber pick up moisture it will later lose. Follow the supplier's instructions – some products are meant to stay sealed until laying.
What is equilibrium moisture content?
Equilibrium moisture content (EMC) is the moisture content timber settles at when it has stopped gaining or losing moisture to the surrounding air. It depends mainly on relative humidity and, to a lesser extent, temperature.
Does air-conditioning affect acclimatisation?
Yes. Air-conditioning and heating lower indoor humidity, so timber in a conditioned home usually settles at a lower EMC than outdoor air would suggest. Acclimatise with the home running as it will be lived in.
What happens if oak flooring isn't acclimatised?
Boards laid too wet shrink as they dry, opening gaps between blocks. Boards laid too dry take up moisture and swell, which can cause cupping, peaking or lifting. Both problems are much harder to fix after the floor is glued and finished.