Page 59 - Construction Waterproofing Handbook

BELOW-GRADE WATERPROOFING 2.23

FIGURE 2.32 Field quality-control procedures ensure successful
installation of waterstop. (Courtesy of J.P. Specialties)

Capillary action begins by liquid water saturating lower areas adjacent to the water
source. This transgresses to a mixture of liquid and vapor above the saturation layer.
Finally, only vapor exists in upper soil areas. This vapor is as damaging as water to inte-
rior building areas. Soil capillary action can add as much as 12 gal of water per day per
1000 sf of slab-on-grade area if insufficient waterproofing protection is not provided.
Microscopic capillaries and pores that naturally occur in concrete substrates create the
ability for the concrete to allow water and moisture to move readily through below-grade
walls and floors. This process is particularly sustainable when the interior space of the
structure has lower humidity than the 100% humidity of the adjacent water-saturated soil
and when the occupied space is warmer than the soil. These conditions present ideal cir-
cumstances for water to be actually drawn into the occupied space if not protected with
waterproofing materials or at minimum vapor barriers where appropriate.
Water vapor penetrates pores of concrete floors, condensing into water once it reaches
adjacent air-conditioned space. This condensation causes delamination of finished floor