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
CLC and BSR process map for HRB approvals
One of the initial outputs of their weekly BSR meetings.
Building Safety Levy technical consultation response
Details of the planned levy now due in 2026.
Great British Energy install solar on school and NHS sites
200 schools and 200 NHS sites to get solar systems, as first project of the newly formed government initiative.
600 million for 60,000 more skilled construction workers
Announced by Treasury ahead of the Spring Statement.
The restoration of the novelist’s birthplace in Eastwood.
Life Critical Fire Safety External Wall System LCFS EWS
Breaking down what is meant by this now often used term.
PAC report on the Remediation of Dangerous Cladding
Recommendations on workforce, transparency, support, insurance, funding, fraud and mismanagement.
New towns, expanded settlements and housing delivery
Modular inquiry asks if new towns and expanded settlements are an effective means of delivering housing.
Building Engineering Business Survey Q1 2025
Survey shows growth remains flat as skill shortages and volatile pricing persist.
Construction contract awards remain buoyant
Infrastructure up but residential struggles.
Home builders call for suspension of Building Safety Levy
HBF with over 100 home builders write to the Chancellor.
CIOB Apprentice of the Year 2024/2025
CIOB names James Monk a quantity surveyor from Cambridge as the winner.
Warm Homes Plan and existing energy bill support policies
Breaking down what existing policies are and what they do.
Treasury responds to sector submission on Warm Homes
Trade associations call on Government to make good on manifesto pledge for the upgrading of 5 million homes.
A tour through Robotic Installation Systems for Elevators, Innovation Labs, MetaCore and PORT tech.
A dynamic brand built for impact stitched into BSRIA’s building fabric.
BS 9991:2024 and the recently published CLC advisory note
Fire safety in the design, management and use of residential buildings. Code of practice.