(A Footer is a 12-Inch-Deep by 16-inch-wide slab of concrete around the bottom of you Foundation) From a bird’s eye view the Footer looks like a side walk around your basement. It is place in the hard pan clay of the bowl in which your home’s foundation is built.
Cracks in the footer are caused by pressure from water forcing its way underneath the footer washing away the clay and gravel surrounding the footer. As the earth beneath the footer moves the footer cracks and moves.
(Floor is a slab of concrete poured after the Footer and Walls are placed in the home.)
Newly poured concrete and dry concrete do not bound together. Since the floor is poured separately after the footer and walls are built there is a natural seem between the wall, footer and floor. This is where water first appears. Usually you will see water in the corner near the where the wall, footer and floor meet.
The reason this occurs is due to the hydrostatic pressure that is created when water forces its way around the walls, underneath the footer and pushes on the floor. Hydrostatic pressure is pressure that is exerted at equilibrium at a given point within fluid due to the force of gravity. Hydrostatic pressure increases in proportion to depth from the surface due to the increased weight from the fluid exerting downward force from above. This pressure causes water to enter through the natural seem between the wall, footer and floor as well as push water up through the center of the floor.
(Wall is usually made from Cinder Block, Poured Concrete, Brick or Stone)
Wall cracks are created through several different ways:
- Lack of Parging and Tar – When you home was first build the builder puts a layer of parging and tar on the outside of your foundation wall. Over time the tar wears away just as the asphalt on you roof wears away and needs to be replaced. As the parging and tar disappear, water and ground acidity have direct access to your foundation wall.
- Improper Backfill – When the builder used a bull dozer to push in the backfill around your foundation the pressure against a wall caused a crack.
- Ground water – Water accumulates in the backfill area of your home and starts to pressure on your wall. Ground water gathers the Acid in the ground and deposits it against the wall of your home. Acid starts to eat away at the wall of you home and creates cracks in the foundation wall.
- Settlement – When the home settles in to the ground clay the walls move slightly and crack.
- Water is absorbed into the foundation wall and the area above the freeze line. The depth of the freeze line is 24 inches in Virginia. As the temperature cools and warms the wall expands and contracts. This causes cracks in the foundation wall.