Unless all necessary measures are taken, and thoroughly executed, the part of a building that is below grade will most likely be troubled from time to time with intruding water. Water is most likely to enter at construction joints, transitions, junctions of two different construction materials, or places where the work of one trade ends and another begins. Most often it enters through shrinkage or structural cracks. Probably the most important thing in waterproofing is to draw as much water away from the wall as possible.
PROVIDING DRAINAGE AND RUNOFF
Beginning at the foundation, certain elements are necessary for good drainage and runoff. Using tile is essential, whether rigid or flexible and whether inside or outside the footings or both. A good backfilling job minimizes hydraulic pressure on the wall. The backfill material should be free-draining granular material of rock retained on the 3/8-inch screen and passing the 3/4- or 1 1/2-inch screen. Concrete flatwork such as sidewalks, driveways, patios and stoops should be designed to slope away from the house at the rate of 1/2 inch per foot so they don't trap water next to the wall.
THE WATERPROOFING MEMBRANE
Waterproofing membranes come in all types. The main classifications of materials are given here:
- Cementitious systems
- Liquid-applied solvent systems
- Preheated liquid-applied systems
- Manufactured sheet systems