The expansive soil in Colorado is one of the main reasons that there is risk in not mitigating water correctly. The American Society of Civil Engineers estimates that 1/4 of all homes in the United States have some damage caused by expansive soils. When water saturates this soil, it swells up to 110% of its volume. When this is the soil under your home, the home can be moved enough to cause cracking of foundation walls, drywall, and damage to the house’s structure. Learn more about expansive soils.
Another common cause of water damage is water getting into the basement of a home. This is caused when snow-melt fills lakes, reservoirs and underground bodies of water and the water table rises higher than the basement floor. It is also caused when there are heavy rains or an abundance of sprinkler water that saturates the soil, causing excess water to find its way to the bottom of a foundation.
A well installed perimeter drainage system installed below the concrete floor in the basement at the time of construction is the key component.
A perimeter drain system is installed using PVC pipe with perforations and placed on the inside or outside of the foundation wall or footing. The pipe is trenched into the dirt and sloped toward the sump pit so that water is always moving rather than saturating the soil. This is covered with a bed of washed rock, usually about 6-12 inches in depth over the pipe. This system allows water to “follow the path of least resistance” when it meets the rock and move into the pipe. The pipe is usually connected to a sump pit, a plastic basin usually 2-3 feet in depth, where the water is collected. A pump is installed in the bottom of the sump pit and pumps water up and out of the house to a discharge point in the lawn.
It is critical to have a perimeter drainage system that works well so that the soil will not be saturated with water causing the soil to expand. It is also important so that when heavy rains and sprinkler water cause large amounts of water to move around the base of the home, the water can be mitigated to a collection area and pumped away from the house.