By Don Carter, Engineer
I assess damaged houses for a living, and I have concluded that if all homeowners were diligent about water management, I'd probably be out of work. Here is why: Most Kansas City area homes are built on expansive clay soil. Clay is the stuff flower pots are made of, and it behaves a lot like Play Dough: it shrinks when it dries and swells when it's wet. Sixty percent of Johnson County soil types are labeled “severe risk for shrink-swell ” by USDA . Still we build houses on them, and to a homeowner, this makes water management a critical issue.
Control water, and you control house movement. Houses are supported on footings. In houses with basements, these footings are typically 8 to 10 feet below ground and sitting on clay soil. If the clay's moisture content remains constant, its ability to support the house remains relatively steady. But if the clay dries out, it shrinks, and then the house settles. Similarly, if the clay gets flooded it becomes plastic and shifts, often taking the house with it. So how does a homeowner protect against clay changes?
Faulty water management can destabilize clay soil under foundation footings thus leading to structural damage of your home. In Part 2 we will address a more serious water-related problem—mold. Absent good water control, water ponding against your house can crack basement walls with a force known as hydrostatic pressure. Water then weeps in through these cracks or via the natural seam between walls and floor.
Either way, you now have the dreaded “wet basement,” a smelly and unhealthy environment. We all recognize mold. It's the black or green slimy stuff that shows up when moisture and low light occur in combination. Whereas most mold is a tolerable annoyance, there is one particularly insidious variety known as Stachybotrys chartarum , commonly called Stachy . Stachy is a serious health hazard for certain people, most notably infants, asthmatics, pregnant women and anyone with lung disease. You may well remember when the State of Kansas SRS office abandoned its space in Olathe because stachy was found in the ceiling that could not be eliminated while the building was occupied.
Stachy produces toxins that may cause Pulmonary Hemorrhage with symptoms such as coughing up blood or nose bleeds. Please know that this hazard is not just limited to occupants, it may well affect visitors who are in your home for only a short time. Stachy is getting enough bad press that we now advise sellers with mold to include it in their real estate disclosure statement to avoid being caught up in a growing number of lawsuits.
Not all mold is as dangerous as stachy. Green mold on bread and cheese or black mold on shower tiles does NOT present the same risk, although a moldy home is never a healthy home. Such things as runny nose, eye irritation, congestion, headaches, dizziness and fatigue have been attributed to the toxic effects of different molds. If you have had plumbing leaks, roof leaks, wet basement or sewer backup in the past year, look for mold or a musty odor. Be alert to water soaked wood, ceiling tiles, wall paneling, unpainted sheetrock, cardboard boxes, and stacks of newspapers. If these areas once wet have dried, the fungus will not continue to grow.
Black dust caused by the fungus can be sucked up into the furnace blower and spread throughout the house. All of which brings us back to the sermon topic—water management. First we advised, “Control the water and you control house movement.” Now we say “control the water and you control mold.”