Capillary Break

Discover the definitions for construction terms, phrases, and acronyms in this comprehensive glossary created for the construction industry.

What is a capillary break?

A capillary break in construction is the use of a hydrophobic material (non-porous material) that acts as a barrier between two layers of material that is able to stop capillary action.

More in depth definition of a Capillary Break

Capillary breaks are used to prevent water from entering a building, damaging materials, and causing structural issues. Capillary breaks are incredibly important and are the first line of moisture defense in buildings. While the capillary breaks are generally referred to in the context of concrete foundations it is important to note that capillary breaks are also present in windows, doors, EIFS systems, curtain walls, and more. If a component is on the exterior of a building and is subject to the elements that it will most likely have some form of capillary break, or there will be a reason a capillary break isn’t necessary.

Example of a Capillary Break Being Used

A capillary break is needed before pouring concrete directly on the ground. For example, underneath a slab-on-grade concrete foundation, there will be a layer of non-porous aggregate anywhere from 4-12 inches thick placed and leveled. This ensures that as the concrete dries moisture doesn’t get trapped in the concrete slab and cause cracking as the moisture tries to escape.

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