Concrete Footings: Purpose and Build
Concrete footings are like braces under your house that keep the house from settling unevenly or, in extreme cases, sinking into the ground. If the house settles unevenly, you will see cracks in the foundation, the roof, and the walls, depending on the nature and extent of damage. Entire houses have been lost when the footings were not properly placed or were possibly damaged in an earthquake or flood.
Concrete footings should also be used when putting additions on your house, such as an extra room or a deck. Just as they do for the entire house, the footings balance the weight of these additions and keep your new room or deck from sinking into the ground or settling unevenly.
Unless you know exactly what you are doing, it is best to call a contractor to install the footings for you. Some of the things to keep in mind when installing concrete footings are soil types and how much weight different soils can bear, building codes and climate zones.
Load bearing pressure can vary by as much as 1000 pounds per square foot, depending on whether the soil is sedimentary rock or sandy gravel. Therefore, you must have the soil tested before you build anything on it, and possibly adjust the soil with necessary additives. Check your local building code experts for samples of how much weight particular soils can bear. The concrete footings help spread out the load in the soil and keep the load (weight of your house or addition) balanced.
Anytime someone builds a home or and addition a building permit is required. The permit is issued based on whether or not the project follows all the necessary building codes.
Building codes will vary from city to city, state to state, and sometimes even community to community. There are, of course, some national building codes that are necessary to follow as well. Take a drawing of your project to your local building inspector’s office and confirm that you are placing your concrete footings according to code. The inspector will typically physically inspect the project before, during, and after the footings are in place.
Different climate zones require special attention when installing concrete footings. For example, in hot, arid climates, concrete may show signs of deterioration within a very short time. Therefore, precautions must be used when determining the type and make-up of cement used, coatings, and other treatments necessary to preserve the concrete footings.
In climate zones where freezing occurs, care must be taken to ensure the footing material will not be damaged by frost. Footings should be placed below the frost line and built wider than the wall that will set atop the footings.
In climate zones that have a lot of moisture, contact with water can cause bacteria to grow on the cement and cause it to rot and crumble.
As you can see, there is a lot to consider when installing concrete footings. That is why it is usually best to hire a contractor to do this most important job.