Ever considered the base on which your house is sitting? Yes, there is a foundation between you and the surrounding soils. In general, there are stone foundations bound with mortar mixture to help keep the rocks from slipping past each other.

However, let's consider a little deeper the issue at hand -- on what soil is the foundation sitting? According to Jalisco State Code, all residential homes require a soil study to determine the condition of the land where the house is to be built. The soil study looks at the composition of the various materials that make up the soil, including non-organic materials (i.e. rock, stone, clay, silt, sand and gravel) and organic materials such as top soils, humus and marsh-like materials. The study will determine the conditions of the surface and subsoil layers to determine the capacity of the soils to bear the load of the new construction and usually the recommended type depth, and width of the foundations required.

If organic soil conditions are not an issue and the subsoils are well drained and consolidated, we would dig down to a level where the existing subsoil layer has already been supporting the same pressure that will be exerted by the weight of the new house. With this in mind, we are essentially removing an amount of soil that is equivalent to the weight of the new building (and foundations) to be built on the exposed layer of soil at the foot or base of the foundation. Therefore, the new exposed soil layer will be experiencing the same load that it previously was experiencing with only soil.

As my professor in university once said, “Water is the worst enemy of any civil engineer” and this is very true when considering foundations. Water or the lack thereof, can cause consolidation of soils. Consolidation is the process of compacting the soil particles together, hence eliminating the spaces in-between the particles where typically there is air or water, thus causing the soils to take up less space and become stronger. If you envision the soil like a sponge, the consolidation process happens when you squeeze the sponge and eliminate the air and water it contains.

Consolidation of soils in turn, can cause settlement of the foundations, and anything built on top of them. Settlement can be a problem if it is uneven over the area of the foundations and causes movement in the floors and walls above. This movement then causes a variety of stresses on the walls and floors, which are relieved by cracking in the walls (or floors). Typically this cracking will follow the geometric lines of the forces on the floor or wall and the angle of restitution of the material used. Masonry walls will generally crack in approximately 45-degree angles near the junction or corner where two walls meet.

In areas here at Lake Chapala. . .

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