How to Correct Foundation Drainage

Foundations of homes and other structures may occasionally be threatened by the presence of moisture following rain or melt events or simply because of a consistently high soil moisture content. Poor drainage around the foundation can cause minor seepage or more serious leaks and even structural damage. Address moisture problems by improving or correcting foundation drainage. In some cases, there may be an existing drain that needs to be repaired or corrected. Otherwise, a new, adequate drain or landscape changes may need to be implemented.

Shovel and other digging tools
Tarps
Level
4-inch perforated PVC pipe
Gravel or washed stone
Filter fabric, landscaping cloth or geotextile

Instructions

- 1
  
  Make sure that downspouts direct water away from the foundation.
  
  Inspect the area around the structure and make any simple, necessary adjustments. Make sure that gutters, downspouts or any inlet basins are not clogged. Add extensions to the downspouts if they are releasing water near the structure. Ensure that the landscape slopes away from the house. Often, fill around the foundations settles and creates a negative slope. Correct this by adding and compacting additional soil around the foundation.
- 2
  Excavate a trench along the foundation. If there is an existing drainage system in place, dig to the structure, which could consist of some combination of gravel, filter fabric, tiles or piping. Remove materials, separating them roughly by type onto different tarps. Take out any piping and note possible causes for the drain failure. Determine if it was clogged by silt, broken or too shallow to work effectively. Under most circumstances, the drain should be at the level of the footing. The trench must extend to an outlet, sump pump or a similar structure.
- 3
  Shape the trench. The trench should be about 2 feet wide at the bottom and have a uniform slope between 1 and 2 percent to facilitate water flow away from the foundation.
- 4
  Clean, repair or replace any PVC or other piping that was removed from the drain as long as it is large enough and functional. If there was no piping, lay 4-inch perforated PVC or corrugated plastic piping in the bottom of the trench, making sure it has a uniform slope and extends to an outlet.
- 5
  Place at least 12 inches of clean, coarse gravel or washed stone on top of the pipe. If gravel was removed from the drain, clean it before replacing it.
- 6
  Lay filter fabric on top of the gravel layer. Filter fabric or landscaping cloth will allow water to pass while blocking sediments that could clog the pipe and gravel.
- 7
  Fill the remainder of the trench and area excavated with gravel, rubble or soil.

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