Dictionary of Moisture Protection & Restoration

Capillary action:

Capillary action happens in situations where water is absorbed by wicking action. This will happen mostly with masonry and concrete at or below grade levels. These materials have a natural high degree of minute void space within their composition. These minute voids actually create a capillary suction force that draws water into the substrate when standing water is present. This is similar to the action of a sponge laid in water and absorbing the water. Ironically, materials that have large voids or are very porous are not susceptible to capillary action in buildings. For example, sand is often used as a fill below concrete slabs to prevent the concrete from drawing water from the soil through capillary action. Compacted sand and Pea Gravel fill. Waterproofing membrane

Waterstop The best way to prevent capillary action is to install a good barrier. In this case the barrier can be a waterproofing membrane, waterstops and compacted sand and pea gravel fills.

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