People love basements until they have to live with one
I've heard many people say, if you have a basement it's not a matter of if it will flood, but only when.
Of course there are many reasons for a basement to flood. One friend had a sump pump outlet pipe that froze, so the water-pressure driven pump broke and the water flowed into the house. The basement flooded just after they got back from Christmas vacation. Fortunately, it wasn't the waterproofing that failed in this case.
But all too often a basement or crawl space is susceptible to water flowing or seeping in through the foundation walls. That's a sign of poor waterproofing system design and performance.
The best waterproofing systems take a multilayered approach. First, the wall is coated with a high performance waterproofing membrane. There are many types; choose one that's formulated for the type of wall, such as poured concrete, block, or insulated concrete forms. There should be drainage board over top of the membrane. The board helps direct water away from the wall, and protects the membrane during backfilling, and also from soil contamination over the years.
The purpose of the membrane and the board is to direct the water to the drainage tile. That helps lower the hydrostatic pressure of the water against the foundation wall. Water can seep through block or through the footer/wall joint.
Of course, the best time to waterproof a building is while it's under construction. While it's not impossible to waterproof a basement that has already been constructed, it can be expensive. Many buildings that were meant to last the test of time were constructed before basement waterproofing technologies, such as our Shockwave drainage board, were developed. In these cases, or others where the building’s value merits the expense, the foundation can be exposed, have a waterproofing system installed and then be reburied.
If you're considering building a home with a basement, make sure your architect or contractor specifies a multi-layer foundation waterproofing system. That way you can put the thoughts of a leaky basement out of your mind.