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Wet Basement Issues


One of the most common problems that I encounter as a home inspector is wet basements. Most are minor issues; a puddle near a corner of the basement or some moist areas under the stairs. But some are catastrophes. I've seen 3 feet of water in a basement when a spring snow melt coincided with a heavy rain. The cost of these disasters can be enormous for home owners and insurance companies, and devastating to property values if the wet basement issues are not addressed.


Signs of a Wet Basement

   If you're buying a home, you'll want to be able to spot signs of a wet basement BEFORE you make an offer on the property. Standing water is a dead giveaway, but there are less obvious signs that you need to look for as well:

  > Musty odors
  > Efflorescence
  > Spalling concrete
  > Mold
  > Sunken concrete floor
  > Sump holes
  > Slumping basement walls
  > Horizontal cracks in walls caused by hydraulic pressure

Let's examine these one at a time.

ODORS: If a basement has an ongoing problem with water infiltration, there will usually be a tell-tale odor left behind. Musty odors may hang around a long time after the water issue has been corrected.

EFFLORESCENCE: When water soaks into concrete, particularly concrete block, it leaches out the salt and mineral deposits within the concrete. The dry, white, chalky residue left behind is known as efflorescence. It can usually be seen on the basement walls, but you may see this occurring on concrete floors as well. It is one of the best indicators of a wet basement, since the efflorescence can pinpoint where the water is entering the basement.

SPALLING: Water in a concrete wall can cause the concrete to flake away or pop loose, creating a hole or pocket on the interior wall.

MOLD: Mold is very opportunistic, and can lie dormant for years before it springs to life. The slightest hint of moisture is all it needs. Even relatively dry basements may have mold growths; since many basements are poorly ventilated, water condensation may feed the mold spores and cause them to grow. In the case of a (continually) wet basement, the mold growth will be more prolific.

SUNKEN CONCRETE FLOOR: Sometimes one particular area of a basement has an ongoing water infiltration problem, and it causes a portion of the basement floor to drop slightly. As the soil beneath the floor becomes saturated, the soil compacts, or in some cases is washed from beneath the floor. These sunken areas are usually found near the corner of a basement.

SUMP HOLES: If a home has a sump pit, or a sump pump, it's a pretty sure bet that there has been a wet basement issue at some point in time. There are exceptions; a sump pump is sometimes used to pump water from under the floor slab if there happens to be an underground spring or vein of groundwater nearby. But as a rule, if there is a sump pump, a sump pit, or both, look for signs of water encroachment.

SLUMPING WALLS: Sometimes a drainage issue at the exterior of the home can cause water to soak into a basement wall. As the water leaches out minerals from the wall, it weakens the bond between the concrete an the aggregate material used in it (usually gravel). This can cause a basement wall to soften, and "slump". Reinforcing rod within poured concrete walls usually help the wall retain it's strength, fortunately. A bulge may be seen on the wall surface, or you may notice a gap between the top of the wall and the sill plate.

HORIZONTAL CRACKS: If a drainage issue exists OUTSIDE the home, the saturated soil may cause a basement wall to crack horizontally. This is especially true in colder climates, where the water may freeze and expand, pushing the wall inward.




   One of the biggest reasons for a wet basement is POOR DRAINAGE. Lack of roof drainage systems (gutters) and leaking gutters can lead to a soggy basement. If the home has a gutter system, the water must be directed far enough away from the home to prevent water from seeping back toward the basement.
    Many people make the mistake of installing gutters and terminating the downspout right beside the building. This defeats the purpose of the system by channeling all the rain water from the roof to ONE site next to the basement wall. Eventually, the water will find it's way inside.
   If the downspout is terminated beside the home, the water can be directed into a length of buried drain tile to get the rain water at least 10 feet away from the wall.


   The site plan of a home can affect drainage in several ways. Homes that are built below a hill are susceptible to drainage problems because the hill will naturally channel water toward the home. The excess water can be directed around the home by installing drainage tile between the hill and the house, and draining the water to either side toward a downhill gradient.


   When excavation is done for a new basement, some of the original soil is used to back-fill around the basement after it is constructed. Depending upon the soil composition, this can create problems with regard to a wet basement. Soils that are TOO permeable can create a direct channel for water into the basement unless a drainage system is installed. Soils that are too IMPERMEABLE, like clay soils, can hold water near the basement wall and eventually allow it to slowly seep inside. 
   In either case, a good drainage system can prevent problems with water intrusion. A properly installed roof gutter system, along with the installation of drainage tile near the basement footer, can head off wet basement issues.


   A sprinkler system is a wonderful thing....saving time and water. But if the sprinkler water is poorly directed, or if the system runs too long and over-saturates the soil, it can lead to a wet basement.
   Be sure that sprinkler systems don't spray water too close to a basement wall, and make sure the timer works properly so that the lawn doesn't become too wet. An over-saturated lawn will eventually show itself as standing water or efflorescence in the basement.


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