Vapour pressure
Course Handbook: Level 3 Award in Energy Efficiency Measures for Older and Traditional Buildings, published by Historic England in December 2024, defines vapour pressure as: 'The pressure exerted by molecules of water vapour in gas form. This can exert considerable force — for example, enough to blister paint. Warm, moist air has a higher pressure than cold, dry air. A high moisture content will create a large amount of vapour pressure. Vapour diffuses through building materials at a rate proportional to the vapour pressure difference. If one side of a wall is much dryer than the other, the vapour will diffuse faster.'
See also Saturation vapour pressure
[edit] Related articles on Designing Buildings
Featured articles
Check out some of the best features and news from Designing Buildings as well as key stories from around the web.
Households living near new pylons to save on bills.
ECA warns growth must not outpace grid capacity or skills.
The role of the client and decision making
CIOB response to built environment professions call for evidence.
Construction's sustainability reporting revolution
Tracking upfront embodied carbon with digital tools.
ECA welcomes procurement reforms
Public spending must back British jobs and skills.
Campaigning for Edinburgh: the Cockburn Association 1875-2049
The role of the civic voice in protecting character. Book review.
CIOB photography competition is open for entries.
ECA Edmundson apprentice of the year award
Finalists announced.
Major new study exposes serious knowledge gaps.
Generating energy from internal light as well as sunshine.
ECA welcomes plans to strengthen subcontractor quality control.
Combining mid-career qualifications with experience broadens career opportunities.

















