# Moisture content in timber flooring

> Moisture content in timber flooring explained: MC vs EMC, the 8–14% Australian interior range, the ±2% rule, and how to measure oak and slab moisture.

- URL: https://timbo.com.au/guides/moisture-content-timber-flooring
- Publisher: Timbo (https://timbo.com.au) – trade supplier of European oak floorboards to partners in Australia and New Zealand
- Last updated: 2026-10-14
- Contact (email only): partnerships@timbo.com.au

## Key facts

- Moisture content (MC) is the weight of water in timber as a percentage of the timber's oven-dry weight.
- Australian-made timber floorboards average about 10–12% moisture content at supply, according to the ATFA specification.
- Typical Australian interiors produce an equilibrium moisture content of about 8–14%.
- Timber flooring should be installed within about ±2% of its expected in-service EMC.
- Slab moisture and timber moisture are measured differently and have separate limits.

## What is moisture content?

**Moisture content (MC) is the amount of water in timber, expressed as a percentage of the timber's oven-dry weight.** A board at 10% MC contains water equal to 10% of the weight of the dry wood in it.

Timber is **hygroscopic**: it constantly exchanges moisture with the surrounding air. When the air is humid, timber takes up moisture and swells; when the air is dry, it releases moisture and shrinks. Most of that movement happens across the width of a board rather than along its length.

## MC vs EMC

**MC is what the timber is now; equilibrium moisture content (EMC) is what it will settle at in a given environment.** The goal of drying, storage and acclimatisation is to get MC close to the in-service EMC before the floor is laid.

| Term | Meaning | Example |
| --- | --- | --- |
| **MC** | Measured water content of the board | Meter reads 11% |
| **EMC** | Level the timber settles at in given temperature and humidity | ~11% at 25°C and 60% RH ([ATFA](https://www.floorchoices.com.au/information-sheets/acclimatisation-of-timber-flooring/)) |
| **In-service EMC** | The EMC range in the finished, occupied building | ~8–14% in typical Australian interiors ([WoodSolutions](https://www.woodsolutions.com.au/timber-wiki/moisture-guide)) |

## Key numbers for Australia and New Zealand

**Australian-made boards average about 10–12% MC at supply, interiors sit at about 8–14% EMC, and timber should be installed within about ±2% of its in-service EMC.**

| Figure | Value | Source |
| --- | --- | --- |
| Average MC of Australian-made floorboards | ~10–12% | [ATFA specification](https://www.atfa.com.au/wp-content/uploads/2023/01/ATFA-Specification-for-Solid-Timber-Flooring-FINAL-Oct-18-.pdf) |
| EMC at 25°C / 60% RH | ~11% | [ATFA](https://www.floorchoices.com.au/information-sheets/acclimatisation-of-timber-flooring/) |
| EMC at 80% RH | ~16% | [ATFA](https://www.floorchoices.com.au/information-sheets/acclimatisation-of-timber-flooring/) |
| Typical Australian interior EMC | ~8–14% | [WoodSolutions](https://www.woodsolutions.com.au/timber-wiki/moisture-guide) |
| Installation tolerance | within ±2% of in-service EMC | [WoodSolutions](https://www.woodsolutions.com.au/timber-wiki/moisture-guide) |
| NZ slab benchmark (solid strip flooring) | ≤75% RH at slab surface | [BRANZ BU644](https://www.branz.co.nz/documents/4063/BU644_Solid_timber_strip_flooring_on_a_concrete_slab.pdf) |

Specifiers can also refer to NATSPEC's technical note on moisture content in timber floors ([NATSPEC DES 002](https://www.natspec.com.au/images/TECHnotes/NTN-DES-002-Moisture-content-in-timber-floors.pdf)).

Imported timber passes through very different climates during shipping and storage, so its MC on arrival can differ from what it left the mill at. Timbo does not publish a dispatch MC figure on this website – measure the timber on arrival.

## How to measure timber moisture content

**Use a calibrated moisture meter with the correct species setting, take readings from several boards across several boxes, and record them.**

1. **Choose the meter.** Pin (resistance) meters read between two pins driven into the wood; pinless (capacitance) meters read through the surface. Both need correct settings for oak.
2. **Set species and temperature corrections.** Readings on oak can differ from a default setting; use the meter's oak setting or correction table.
3. **Sample widely.** Take readings from a selection of blocks from different boxes – not just the top box.
4. **Read away from ends.** Board ends dry and wet faster than the middle.
5. **Measure the site.** Record indoor temperature and relative humidity over several days to estimate in-service EMC.
6. **Compare and decide.** If boards are within about ±2% of the target, proceed; if not, keep acclimatising or investigate why.
7. **Record everything** – readings, locations, meter, settings and date – in the job file.

For the process of getting timber to target, see [acclimatising oak flooring](https://timbo.com.au/guides/acclimatising-oak-flooring).

## Slab moisture is a separate test

**Concrete slab moisture is not measured with a timber meter; it's tested with the method and against the limit the adhesive or moisture-barrier manufacturer specifies.** In New Zealand, BRANZ uses ≤75% relative humidity at the slab surface as the benchmark for solid timber flooring. In Australia, the adhesive maker's limits govern ([Bowens](https://bowens.com.au/blog/hardwood-timber-flooring)). See [installing parquet over a concrete slab](https://timbo.com.au/guides/installing-parquet-over-concrete-slab), the [NZ slab guide](https://timbo.com.au/guides/timber-flooring-over-slab-nz) and [adhesives and moisture barriers](https://timbo.com.au/guides/adhesives-and-moisture-barriers).

**Talk to the Timbo team:** Questions about specifications, stock or partnering? We reply during business hours, Monday to Friday. → https://timbo.com.au/pages/contact-us

## What goes wrong when moisture is out

**Too wet at installation means shrinkage and gaps later; too dry means swelling, cupping, peaking or lifting.**

| Symptom | Likely cause | First step |
| --- | --- | --- |
| Gaps between blocks or boards | Laid too wet, or very dry indoor air (heating) | Check indoor RH; compare with MC at install |
| Cupping (edges high) | Moisture from below – damp slab, leak, poor ventilation | Find the moisture source |
| Crowning (centre high) | Often from sanding a cupped floor too early | Let the floor stabilise first |
| Peaking or lifting | Swelling with no room to expand | Check expansion allowance and moisture source |
| Hollow-sounding blocks | Bond failure – often slab moisture or poor preparation | Investigate adhesive and slab |

Seasonal movement is normal. Solid oak floors open slightly in dry months and close up in humid months. Good acclimatisation and correct [expansion gaps](https://timbo.com.au/guides/expansion-gaps-solid-parquet) keep that movement within acceptable limits.

## Moisture through the life of the floor

**Moisture management doesn't stop at installation – the floor responds to its environment every season.**

| Stage | Moisture risk | Good practice |
| --- | --- | --- |
| Delivery and storage | Damp site, open boxes, rain during unloading | Deliver to an enclosed, dry site; store off the slab |
| Installation | Damp slab, wet trades, timber outside ±2% | Test, record, acclimatise |
| First year | Floor settling through its first seasons | Keep indoor conditions steady; expect minor seasonal movement |
| Everyday life | Spills, wet mopping, leaks, pot plants | Wipe spills quickly; fix leaks; use the finish maker's cleaner |
| Long absences | Closed-up house swings in humidity | Ventilate or condition the home where practical |

For installers, a short moisture record – slab readings, board readings, indoor RH and the products used – is the best evidence if a question arises later.

## Practical tips for homeowners

- **Keep indoor humidity steady.** Avoid running humidifiers or dehumidifiers to extremes.
- **Watch the first year.** New floors settle through their first full set of seasons.
- **Fix leaks fast.** Water from a dishwasher, fridge line or pot plant can damage a floor quickly.
- **Ask your installer for the moisture readings** they took – they're part of a good job record.

## Sources

- [ATFA – Specification for solid timber flooring](https://www.atfa.com.au/wp-content/uploads/2023/01/ATFA-Specification-for-Solid-Timber-Flooring-FINAL-Oct-18-.pdf)
- [ATFA (floorchoices.com.au) – Acclimatisation of timber flooring](https://www.floorchoices.com.au/information-sheets/acclimatisation-of-timber-flooring/)
- [WoodSolutions – Moisture guide](https://www.woodsolutions.com.au/timber-wiki/moisture-guide)
- [NATSPEC TECHnote DES 002 – Moisture content in timber floors](https://www.natspec.com.au/images/TECHnotes/NTN-DES-002-Moisture-content-in-timber-floors.pdf)
- [BRANZ BU644 – Solid timber strip flooring on a concrete slab](https://www.branz.co.nz/documents/4063/BU644_Solid_timber_strip_flooring_on_a_concrete_slab.pdf)
- [Bowens – Hardwood timber flooring](https://bowens.com.au/blog/hardwood-timber-flooring)

## Frequently asked questions

### What moisture content should timber flooring be when installed?

Within about ±2% of the equilibrium moisture content it will reach in service. In Australia that in-service EMC is typically somewhere between about 8% and 14%, depending on location, season and heating or cooling.

### Are pin and pinless moisture meters accurate on oak?

Both can be reliable when used correctly. Pin meters need the right species setting and temperature correction; pinless meters need the right density setting and a flat, clean surface. Check several boards and compare with a calibrated reference where possible.

### Can I use a timber moisture meter on a concrete slab?

Not for an acceptance test. Timber meters read timber. Slab moisture is tested with the method the adhesive or barrier manufacturer specifies – often relative humidity – and compared with that manufacturer's limit.

### What moisture content is imported European oak flooring supplied at?

It varies with the mill's drying, packaging, shipping and storage, so don't assume a figure. Measure a sample of blocks on arrival and compare with the site's expected in-service EMC. For context, the ATFA specification says Australian-made boards average about 10–12% MC.

### What causes cupping in timber floorboards?

Cupping – edges higher than the centre – usually means the underside of the boards is wetter than the top, often from a damp slab, a leak or poor sub-floor ventilation. Find and fix the moisture source before considering any sanding.

### Does a finished floor stop moisture movement?

No. Finishes slow moisture exchange but don't stop it. Timber floors keep moving a little with the seasons, which is why acclimatisation and expansion allowances matter.

## Related pages

- [Acclimatising oak flooring](https://timbo.com.au/guides/acclimatising-oak-flooring) – How to acclimatise oak flooring in Australia and NZ: equilibrium moisture content (EMC), ATFA figures, the ±2% rule, climate examples and a step-by-step method.
- [Installing parquet over a concrete slab](https://timbo.com.au/guides/installing-parquet-over-concrete-slab) – How to install solid oak parquet over a concrete slab in Australia: flatness (~3mm/3m), moisture testing, barriers and adhesives, setout, gluing and finishing.
- [Adhesives and moisture barriers for timber flooring](https://timbo.com.au/guides/adhesives-and-moisture-barriers) – Adhesives and moisture barriers for solid oak parquet on slabs: adhesive types, moisture-barrier adhesives, separate barriers and why maker limits govern.