Basement or Crawlspace Moisture and Water Entry
Article Provided by
Richard Castell “Chip”
Castell Home Consultants, Inc.
Basement moisture could be coming from inside the house, caused by plumbing leaks, or from outside the house, caused by poor roof and surface water control or a high water table. Poor roof and surface water control allows water to collect or pond at the house foundation wall, and wick or seep through the wall to the inside. A high water table causes water to come up through or around the edges of the basement or crawlspace floor. There are some instances where old stream beds or springs are covered by the house. Most exterior water entry is caused by poor roof and surface water control.
Solutions:
Surface water control: Improve the exterior grading.
Proper grade: The earth around the house should slope away from the house at a rate of 1 inch fall for every 12 inches away from the house. This positive grade should extend at least 4 to 6 feet away from the house, if possible. All patios driveways and other hard surfaces should also slope away from the house.
Roof water control: Extend downspouts away from house.
The bottom of the downspouts should be equipped with an elbow, to start the roof water flowing away from the house. The elbow will lead water onto a splash block or into an extension pipe which can be extend away from the house as far as needed to help control roof water.
High water table or extreme seepage control: Add sump and drain tile system.
Sump systems work to remove water from high water tables. However they should be a last resort for water seepage through the walls. Sump pumps and perimeter drain tile systems can be very expensive systems to install and are often unnecessary in dealing with water seepage through the walls. The typical sump system includes a sub-slab perimeter drain tile system to collect water and lead it to the sump pit, a sump pump placed in the sump pit and piping to the exterior of the house. When water enters the sump pit a float switch activates the sump pump and it discharges the collected water at grade on the exterior of the house.
Improved grading and extended downspouts may control enough water to eliminate the need for a sump pump system. Sump pump systems do not help eliminate the cause of water seepage through the walls, but merely pump the water out once it enters. Removing the water source is preferable.
Many, if not most water entry problems can be significantly reduced or eliminated by regrading around the house perimeter and extending downspouts away from the house walls. This allows both roof and surface water to be controlled away from the foundation walls. Removal of the water helps keep foundation walls dryer. Regrading can best be accomplished by landscape contractors.
Note: In extreme cases, when the waterproof coating on the exterior of the foundation wall has failed, and all other methods of water control have not been effective, excavation around the house and resealing the foundation walls from the exterior may be deemed necessary. This is a very expensive operation and should be done as a last resort.
