# Hygroscopic

**Describes a material that exchanges moisture with the surrounding air continuously, rather than reaching a fixed state.**

Wood is hygroscopic: it takes on and gives off moisture with the air around it for as long as it exists. It never stops. A floor installed in February is in a different moisture state in August, and back again the following winter.

This is the single property that makes every other rule in hardwood installation necessary. Moisture testing, acclimation, expansion gaps and a stated humidity operating range all exist because the material is never inert.

## Related terms

- [Anisotropic](https://ecowoods.ca/glossary/anisotropic)
- [Moisture content](https://ecowoods.ca/glossary/moisture-content)
- [Acclimation](https://ecowoods.ca/glossary/acclimation)
- [Relative humidity](https://ecowoods.ca/glossary/relative-humidity)


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- Defined in: https://ecowoods.ca/papers/toronto-hardwood-climate-moisture-protocol#climate-reality
- Citation guide: https://ecowoods.ca/ai.txt

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