- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 26 May 2020
|Capillary action causes the water in the thinnest tube to rise to a higher level than in the other tubes|
Capillary action is a phenomenon associated with surface tension, whereby liquids can travel – horizontally or vertically (against the force of gravity) in small spaces within materials. It is sometimes referred to as capillary attraction, capillarity or wicking.
The movement is due to the surface tension that results when liquid or moisture is contained within very fine spaces or tubes (capillaries). Essentially, the liquid is attracted to the sides of the container; the smaller the space, the greater the attraction. Examples of capillarity include the action observed when a paper towel or blotting paper absorb water, and the way oil travels up a wick in oil lamps.
Rising damp in concrete and masonry is also the result of capillary action. When building materials such as most brick types, some stones, concrete blocks and plaster come into contact with moisture, the water adheres to the pores of the material’s capillaries. If the adhesive force between the water molecules and the material is greater than the cohesive force existing between the water molecules themselves, the water rises up the tube through capillary action.
Typically, damp can rise up to around 1m above its source. It is usually prevented from doing so by the installation of a damp-proof course (DPC), typically a polymerised rubber material such as bitumen polymer. Installed as the brickwork goes up and bedded both sides with mortar, the bond between DPC, mortar and walling material creates a barrier to moisture rising through capillary action.
Leonardo da Vinci is regarded as being the first person to observe and record capillary action.
 Related articles on Designing Buildings Wiki
Featured articles and news
How can these valued spaces be reused?
Partnership avoids the need for listed building consent.
Connecting building design from inception to completion to operations.
Gregor Harvie predicts interoperability will be construction’s Uber moment.
Expert commentary and insight.
Guidance offered for stained glass window maintenance.
Define need before determining viability.
Framework examines social value of projects.
RfX or Request for [fill in the blank].
Organisation establishes Equality, Diversity, Inclusion taskforce.
Government announces plans for new building projects.
Outsourcing method to procure and manage supplies.
Joint support of Local Authority Historic Environment and Conservation Services.
The Chesapeake Bay Bridge-Tunnel is an outstanding achievement.
Buildings of the interwar years. Book review.