Effective drainage begins by directing rainwater runoff from the roof away from the house. This can be accomplished with a 5 to 10 foot tube attached to the bottom of the downspout. Local conditions may require a shorter tube or some other means of accomplishing the desired outcome.
When rain water does enter the ground near the building, it is desirable to have it flow freely down to the foundation drainage system. Depending on soil type and climate, there may be a tendency for water to accumulate around the foundation, so it is essential to move ground water away through foundation drainage. One way to improve the flow of water along the foundation wall and create foundation drainage is to back-fill the side of the foundation with gravel. Crushed stone does not pack well and allows water to move easily through the stone to the footing drain. Another way to improve foundation drainage is to install a drainage board against the foundation surface. The board creates a foundation drainage path to the footing.
It is the job of the foundation drainage system to capture water near the foundation, and move it away from the house. This is usually accomplished by channeling water to a sump pump or if the house is on an elevated lot by directing it to a spot lower than the foundation footing. To keep the foundation drainage system’s intake ports from getting clogged, coarse, washed stone covered by a filter fabric is used as a screen for descending ground water.
There is one kind of foundation drainage solution that performs multiple functions at once. Form-A-Drain from CertainTeed
begins as a hollow footing form, but instead of being discarded when the concrete sets the product stays in place to form the structure of the foundation drainage system. The dual purpose structure of the form allows the foundation drainage system to also be connected to a radon mitigation system. Since the form is installed during the construction process, the collection system is already in place if high radon levels are detected when the house is inspected. This is a cost effective alternative to drilling holes in newly constructed floors and walls. Extending around the entire building perimeter, gas venting takes place under the entire house rather than in just one or two discrete locations where post-construction vent pipes are typically located.
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