Lady becomes sick from flooded HVAC under slab ductwork. House Scene Investigation ( HSI) discovers that flooded ductwork exists under the concrete slab. Cleveland home inspector Marko Vovk and special guest Jim Roby an IAQ Mold Expert from STS Technology investigates the condensation on windows and mold growth on walls. When the new homeowner purchased the home, the disclosure was very vague. The backyard was wet with a natural spring. Backyard is wet a may have a high water table. This means that water soil pressure (hydrostatic) existed under the concrete slab. The investigator installed temperature, humidity, and dew point USB computer probes throughout the home. The probes identified where the moisture source was coming from. The probe data was downloaded and the results were studied. From the probe data, it was determined that the home moisture source was coming from the soil below the slab. The exterior inspection revealed that water was running down the east downspout splash block. The driveway had a negative slope and permitted the water to run back towards the west foundation. The water entered the driveway foundation interface crack. The front of the home also had poor grading and water was ponding at the foundation. The back of the home also had water ponding at the foundation. These poor exterior water management conditions along with a potentially high water table permitted hydrostatic pressure to push water under the homes slab and into the HVAC ductwork. We located the supply main HVAC trunk plenum duct. This main supply plenum duct traveled though the concrete floor slab and traveled under the first floor concrete slab. This main HVAC plenum duct was connected to 6 other supply ducts that traveled under the concrete floor to all the house rooms. We had to cut a hole into the under concrete slab duct to gain access. The high water table, along with the poor exterior water management permitted water to enter into the homes supply ductwork. The ducts were full of mold, bacteria, bio-sludge, bio-growth, and other pollution. Every time the HVAC system was turned on, the home was contaiminated with airborne bio-dust, mold spores, and airborne bacteria. Furthermore, the air had high humidity and was permitting mold growth on walls, ceilings, and cabinets. We used moisture meters to test all the walls and ceilings. We also tested all the walls and ceilings for surface temperature. We found that the coldest areas in the home, had mold, past condensation, and past drywall repairs. The closets, cabinets, and the north side of the home were roughly 5 degrees colder, and when the indoor humidity was high, dew point condensation would occur on cold days. Dew point condensation led to mold and drywall rot. The north east lower corner was the coldest corner in the home, and it had many repair drywall patch histories. It was obvious that previous homeowners battled this water, moisture, and condensation problem. The ceiling also has mold on the outer exterior perimeter. These areas were also cold due to wind-washing which is a term used when the attic insulation gets blown and moved away making the drywall ends colder. Mold grows on these cold areas first. Furthermore, the home has an attic access panel that was not insulated, sealed, or weather-stripped and moist heated air would rise into the attic permitting condensation during cold days, resulting in attic sheathing mold.
In conclusion, repairing this home will not be easy. One repair method that may be successful, would be filling the under slab ductwork with concrete. Changing furnace from a down flow to an up flow. Installing all new overhead supply ducts in all rooms, and adding several return ducts. The new ductwork should be sealed and insulated so thermal bridging, thermal bypass, or heat loss does not occur. The exterior foundation would need to be waterproofed and an exterior dewatering sump pump should be added to lower the ground water elevation. The home would need proper mold mitigation, entire home sanitizing, repair of all thermal bypasses, repair of all thermal bridging, and finally HVAC balancing. These types of repairs are complicated and should only be attempted by building science contractors or consultants. Please rate and subscribe. Please go to http://
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