Case Study 09027: Mold Problems in Split Level House

Facts/History:

-Split level, single family house, early 1970’s construction
-History of water problems into the lower level

• Ground water infiltration
• Lower level bathroom plumbing leak
• Water intrusion behind front steps into crawlspace
• Damp lower level—no known history of dehumidification

-Two forced hot air/central air conditioning system
-Central humidifier on one of the heating systems
-Fully carpeted—upper and lower levels
-Tenants have concerns about mold—people living in the house, including a young child, have had chronic illnesses since moving in less than a year ago.

Observations:

-Mold odor throughout the home but stronger in the lower level
-Visible mold on Sheetrock walls at the floor level in several areas

-Visible mold and rotting materials beneath the lower level stairs (storage crawlspace beneath front steps leading into house)

-Carpeting in lower level was full of dust and dirt

• Dirt and dust inside ductwork
• Fiberglass linings inside air handlers were deteriorated and caked with dust
• Ineffective filters, very dirty
• Central humidifier loaded with visible mold

Sampling Strategy:

-Air sampling to identify mold types and levels throughout the house
-Surface sampling to identify mold types and their extent on building materials and inside the HVAC system

Lab Results:

-Air samples showed elevated mold levels in the lower level (Penicillium was the main mold)
-Basement mold spores have been migrating to the upper level through HVAC ductwork and the open stairwell
-Indoor mold levels higher than outdoors and different mold types found inside
-Mold growth was confirmed on the following surfaces:

• HVAC system components: ductwork, filter, central humidifier, inside air handler
• Sheetrock in the lower level exposed to water
• Rotting wood materials in crawlspace beneath stairs
• Lower level carpeting

Recommendations:

-Professional mold remediation to remove contaminated building materials in the lower level, including carpeting, Sheetrock, rotten wood materials, and more
-Professional HVAC cleaning, system maintenance, and upgrade

– Specialized whole house cleaning
-Identifying and resolving water issues
-Dehumidification in the lower level
-Additional GML recommendations to help prevent mold growth in the lower level