Moisture

Damage & Mold

Moisture Intrusion Through the Building Envelope

Moisture Damage & Mold

Moisture Intrusion Through the Building Envelope

Moisture Damage & Mold

Moisture Intrusion Through the Building Envelope

The owners of a residence in Augusta, Georgia reported persistent mold growth in various locations throughout the home.  The owners suspected that the cause of the mold was related to the HVAC systems serving the house.  The EIS engineer assigned to the project was tasked with performing a site inspection and evaluation of the home’s HVAC systems to determine if they were to blame.

Microbial Growth on Kitchen Cabinet Doors

The home exhibited evidence of microbial growth in multiple locations including in a kitchen cabinet, along the edge of the door to the attic area, around outlet and light-switch covers, and around smoke detectors.  The common characteristic between these areas was that all were a path of infiltration from the exterior of the house to the interior.  The kitchen cabinet exhibiting the microbial growth had a kitchen exhaust duct running through it; the duct was not sealed and had several apparent leaks.  The attic area was an unconditioned space and the electrical junction boxes to the outlets, light-switches, and smoke detectors were all cut into the gypsum board wall, providing a path for air infiltration into the house.  Similarly, the small gap between the attic door and the door jamb provided a path of infiltration.

Microbial Growth Around Smoke Detector

The air-conditioned interior of the house caused the walls, doors, switch and outlet covers, and kitchen cabinets to be cooled to a temperature at or near the interior air temperature.  In the high humidity of the summer, the air infiltrating into the house would have had a very high dew point temperature.  When the dew point of the infiltrating air was greater than the temperature of the walls, switch and outlet covers, and the kitchen cabinets, the moisture in the infiltrating air would condense on the objects.  The resultant wet areas provided a favorable condition for microbial growth.

When operating correctly, an HVAC system will generally remove humidity from the air passing through the system.  When the cooling coil of an air-handling unit is operating at a temperature below the dew point of the incoming air, the moisture in the incoming air will condense on the coil.  The result can be observed as water dripping from the coil is discharge through the condensate drainpipe to a floor drain or to the home’s exterior.  As the air within a home is circulated through the HVAC system to keep the home cooled to the thermostat setpoint temperature, the system has the net effect of drying the air within the house.

Dirty Air Filter

During the site inspection, the engineer discovered that the air filters to the HVAC systems had not been replaced in years.  The filter to the upper level system was extremely dirty and inhibiting the flow of air through the system.  The filter to the lower level HVAC system had gotten so dirty that it had inhibited the flow of air to such a degree that the resultant fan suction ripped the filter media and wire backing from the filter frame and sucked them into the fan.  The fan was thereby rendered inoperable.  With the lower level HVAC system not working and the upper level system unable to operate at full capacity, the systems’ ability to remove moisture from the air within the house was greatly diminished.  The presence of additional moisture within the house would also have contributed to conditions favorable to microbial growth. 

Filter Media Sucked Into Fan

The owners of a residence in Augusta, Georgia reported persistent mold growth in various locations throughout the home.  The owners suspected that the cause of the mold was related to the HVAC systems serving the house.  The EIS engineer assigned to the project was tasked with performing a site inspection and evaluation of the home’s HVAC systems to determine if they were to blame.

Microbial Growth on Kitchen Cabinet Doors

The home exhibited evidence of microbial growth in multiple locations including in a kitchen cabinet, along the edge of the door to the attic area, around outlet and light-switch covers, and around smoke detectors.  The common characteristic between these areas was that all were a path of infiltration from the exterior of the house to the interior.  The kitchen cabinet exhibiting the microbial growth had a kitchen exhaust duct running through it; the duct was not sealed and had several apparent leaks.  The attic area was an unconditioned space and the electrical junction boxes to the outlets, light-switches, and smoke detectors were all cut into the gypsum board wall, providing a path for air infiltration into the house.  Similarly, the small gap between the attic door and the door jamb provided a path of infiltration.

Microbial Growth Around Smoke Detector

The air-conditioned interior of the house caused the walls, doors, switch and outlet covers, and kitchen cabinets to be cooled to a temperature at or near the interior air temperature.  In the high humidity of the summer, the air infiltrating into the house would have had a very high dew point temperature.  When the dew point of the infiltrating air was greater than the temperature of the walls, switch and outlet covers, and the kitchen cabinets, the moisture in the infiltrating air would condense on the objects.  The resultant wet areas provided a favorable condition for microbial growth.

When operating correctly, an HVAC system will generally remove humidity from the air passing through the system.  When the cooling coil of an air-handling unit is operating at a temperature below the dew point of the incoming air, the moisture in the incoming air will condense on the coil.  The result can be observed as water dripping from the coil is discharge through the condensate drainpipe to a floor drain or to the home’s exterior.  As the air within a home is circulated through the HVAC system to keep the home cooled to the thermostat setpoint temperature, the system has the net effect of drying the air within the house.

Dirty Air Filter

During the site inspection, the engineer discovered that the air filters to the HVAC systems had not been replaced in years.  The filter to the upper level system was extremely dirty and inhibiting the flow of air through the system.  The filter to the lower level HVAC system had gotten so dirty that it had inhibited the flow of air to such a degree that the resultant fan suction ripped the filter media and wire backing from the filter frame and sucked them into the fan.  The fan was thereby rendered inoperable.  With the lower level HVAC system not working and the upper level system unable to operate at full capacity, the systems’ ability to remove moisture from the air within the house was greatly diminished.  The presence of additional moisture within the house would also have contributed to conditions favorable to microbial growth. 

Filter Media Sucked Into Fan

The owners of a residence in Augusta, Georgia reported persistent mold growth in various locations throughout the home.  The owners suspected that the cause of the mold was related to the HVAC systems serving the house.  The EIS engineer assigned to the project was tasked with performing a site inspection and evaluation of the home’s HVAC systems to determine if they were to blame.

Microbial Growth on Kitchen Cabinet Doors

The home exhibited evidence of microbial growth in multiple locations including in a kitchen cabinet, along the edge of the door to the attic area, around outlet and light-switch covers, and around smoke detectors.  The common characteristic between these areas was that all were a path of infiltration from the exterior of the house to the interior.  The kitchen cabinet exhibiting the microbial growth had a kitchen exhaust duct running through it; the duct was not sealed and had several apparent leaks.  The attic area was an unconditioned space and the electrical junction boxes to the outlets, light-switches, and smoke detectors were all cut into the gypsum board wall, providing a path for air infiltration into the house.  Similarly, the small gap between the attic door and the door jamb provided a path of infiltration.

Microbial Growth Around Smoke Detector

The air-conditioned interior of the house caused the walls, doors, switch and outlet covers, and kitchen cabinets to be cooled to a temperature at or near the interior air temperature.  In the high humidity of the summer, the air infiltrating into the house would have had a very high dew point temperature.  When the dew point of the infiltrating air was greater than the temperature of the walls, switch and outlet covers, and the kitchen cabinets, the moisture in the infiltrating air would condense on the objects.  The resultant wet areas provided a favorable condition for microbial growth.

When operating correctly, an HVAC system will generally remove humidity from the air passing through the system.  When the cooling coil of an air-handling unit is operating at a temperature below the dew point of the incoming air, the moisture in the incoming air will condense on the coil.  The result can be observed as water dripping from the coil is discharge through the condensate drainpipe to a floor drain or to the home’s exterior.  As the air within a home is circulated through the HVAC system to keep the home cooled to the thermostat setpoint temperature, the system has the net effect of drying the air within the house.

Dirty Air Filter

During the site inspection, the engineer discovered that the air filters to the HVAC systems had not been replaced in years.  The filter to the upper level system was extremely dirty and inhibiting the flow of air through the system.  The filter to the lower level HVAC system had gotten so dirty that it had inhibited the flow of air to such a degree that the resultant fan suction ripped the filter media and wire backing from the filter frame and sucked them into the fan.  The fan was thereby rendered inoperable.  With the lower level HVAC system not working and the upper level system unable to operate at full capacity, the systems’ ability to remove moisture from the air within the house was greatly diminished.  The presence of additional moisture within the house would also have contributed to conditions favorable to microbial growth. 

Filter Media Sucked Into Fan