Where Does Basement Flooding Water Damage Come From?

Life exists on this planet because of an interchange between the earth and the sun, an interchange lubricated with water. The ground we walk on is designed to be an enormous spongy repository of water that can deliver nutrients to the roots of plants that become food on the table. When we enter the moist, life-sustaining skin of the earth by digging or excavating for the foundation of a house, we must keep in mind that we are intruders. Unless we take substantial action, the water and the soil will try to reclaim the space we have taken.

It will be helpful to take a moment to understand the nature of the beast — water — and how it behaves underground. Gravity is our main ally. It takes the rain water or snow melt and tends to draw it straight down through the soil. Water will not move very far in a lateral or sideways direction unless something gets in its way such as a layer of heavy clay beneath the surface — high ledge, large stones, or other subsurface debris, either natural or man made (such as building scraps filled in by the contractor). The direction the water moves underground is referred to as drainage. All things being equal, if the drainage area is of porous soil and free of obstructions, then a dry basement should be relatively simple to maintain.

Few are that fortunate, however. Even in areas with the best drainage, there is still a considerable amount of water near the surface. Water clings to soil particles like a sponge. This normal level of moisture is the culprit for dampness problems. Because the soil is right up against the foundation walls, any cracks or weak spots will let the dampness into your cellar.

The foundation walls must not only hold back tons of soil but also the water contained in that soil. That water can exert a tremendous amount of pressure against the foundation. Soil itself is not a problem because its particles are so relatively large. The liquid water, however, can find its way through the tiniest opening.

Pressure the water exerts on floors and walls is called hydrostatic pressure. Water seeks its own level, the accurate folk wisdom goes, and your foundation is in the way. The ground water surrounding your foundation behaves the same as water in a container such as a tin can. As long as there are no holes in the can, no water will get out. But if you think the water only wants to come out the bottom, take a nail and poke a hole in the side of the can. The water spurts out until the level in the can is below the hole. Standing water exerts pressure against every surface with which it is in contact, and the deeper the water, the greater the pressure.

That is why your ears pop at the bottom of the deep end of the swimming pool, not the shallow end. It is the nature of basements that the weakest point, the wall-floor joint, is also at the deepest level and exposed to the greatest hydrostatic pressures. So before we start spending lots of money on repairs, we now know what is going on down there. Like prisoners digging an escape tunnel with a spoon, hydrostatic pressures are slowly working away on the foundations of our homes. We are as oblivious as the prison guards until after one spring downpour we discover the basement is flooded.