Basic Construction of a Basement
To install a basement or crawlspace into a home, it's necessary to dig a hole bigger than the foundation and its walls to seat the structure inside. These steps are as follows:
- The foundation hold is dug out of the virgin soil, creating an enormous hole.
- The footing is installed inside. This footing is the base of your foundation and is very important. It keeps your house from sinking into the ground and must be strong enough to withstand the continuous forces of nature.
- The walls are built of poured concrete, block, stone and (rarely) out of treated wood.
- Some of the dirt removed by the excavation is backfilled in over the footing.
- The floor is poured between the walls on top of the backfill.
- Usually, a footing drain is installed at this point. Most often, this drain consists of a perforated pipe that lies in a bed of 3/4" of stone. As these stones lay on top of one another, they make 1/2" spaces in between. The purpose of these stones is to filter the dirt out from the water.
Once the construction has been completed, some of the soil was dug out of the hole when the foundation was dug is backfilled back in. Often, this is done very quickly and is backfilled with any stones and other debris that was present in the original soil. This can be a big shock to the cement, which usually has a long way to go before it's cured, and can cause cracks to form. This backfilled soil is looser than the virgin soul around it and will continue to be so for the life of the house. Backfilled soil is looser than the virgin earth and absorbs water more quickly.
