Equilibrium moisture content EMC
Technical paper 35: Moisture measurement in the historic environment, published by Historic Environment Scotland in 2021, defines equilibrium moisture content as: ‘The moisture content at which a material is neither gaining nor losing moisture through exchanges with the ambient environment.’
Equilibrium Moisture Content (EMC) refers to the specific state of a hygroscopic material in relation to its moisture content, and relative to its surrounding environment. It is the point at which the material is neither gaining nor losing moisture and remains in balance or equilibrium with its local environment. The value of the EMC depends on the material being described, as well as the relative humidity and the temperature of its surrounding environment or the air within which it is in contact.
For example, wood is a hygroscopic material, so its moisture levels can rise and fall relative to its local environment. In timber the EMC is most likely to be lower than its Fibre Saturation Point (FSP) which is generally around hen 30%. The exact EMC figure will vary depending on a number of variables which include the type and age of the wood, the area in the cross section of timber and the moisture and temperature of the local environment. For more information see: Fibre saturation point.
This characteristic of hygroscopic materials to help balance moisture and temperature levels can be beneficial to internal environments when left exposed internally.
[edit] Related articles on Designing Buildings
Featured articles and news
A case study and a warning to would-be developers
Creating four dwellings for people to come home to... after half a century of doing this job, why, oh why, is it so difficult?
Reform of the fire engineering profession
Fire Engineers Advisory Panel: Authoritative Statement, reactions and next steps.
Restoration and renewal of the Palace of Westminster
A complex project of cultural significance from full decant to EMI, opportunities and a potential a way forward.
Apprenticeships and the responsibility we share
Perspectives from the CIOB President as National Apprentice Week comes to a close.
The first line of defence against rain, wind and snow.
Building Safety recap January, 2026
What we missed at the end of last year, and at the start of this...
National Apprenticeship Week 2026, 9-15 Feb
Shining a light on the positive impacts for businesses, their apprentices and the wider economy alike.
Applications and benefits of acoustic flooring
From commercial to retail.
From solid to sprung and ribbed to raised.
Strengthening industry collaboration in Hong Kong
Hong Kong Institute of Construction and The Chartered Institute of Building sign Memorandum of Understanding.
A detailed description from the experts at Cornish Lime.
IHBC planning for growth with corporate plan development
Grow with the Institute by volunteering and CP25 consultation.
Connecting ambition and action for designers and specifiers.
Electrical skills gap deepens as apprenticeship starts fall despite surging demand says ECA.
Built environment bodies deepen joint action on EDI
B.E.Inclusive initiative agree next phase of joint equity, diversity and inclusion (EDI) action plan.
Recognising culture as key to sustainable economic growth
Creative UK Provocation paper: Culture as Growth Infrastructure.
Futurebuild and UK Construction Week London Unite
Creating the UK’s Built Environment Super Event and over 25 other key partnerships.
Welsh and Scottish 2026 elections
Manifestos for the built environment for upcoming same May day elections.
Advancing BIM education with a competency framework
“We don’t need people who can just draw in 3D. We need people who can think in data.”