Posts Tagged ‘case studies’

Mold Inspection Journal: 4-1-09

Wednesday, April 1st, 2009

Case Study 09036: Successful Attic Mold Remediation

Facts/History/Observations:

An initial inspection by GML revealed that the mold Cladosporium was actively growing on plywood roof sheathing and on both gable ends in the attic.  A professional mold remediation company was hired to clean all surfaces in attic under environmental controls and using standard mold remediation procedures.  After the work was completed, we re-inspected the attic to determine if remediation was successful. 

Attic insulation was removed, leaving the topside of the second floor ceiling Sheetrock exposed. Among several other important steps, the plywood sheathing was dry-ice blasted (similar to sand blasting except dry ice pellets were used as the abrasive agent).  Visual evidence of mold was no longer present.

Successfully Remediated Plywood Roof Sheathing

Successfully Remediated Roof Sheathing

Inspection Strategy:

  • Visual inspection of attic
  • Surface swab sampling from several representative areas of the previously moldy plywood sheathing

Lab Results:

  • Lab results describe a negligible amount of mold spores
  • The current level of mold on wood materials in the attic is normal
  • Remediation was completely successful

Recommendations:

  • Maintain a dry and well ventilated attic
  • Re-install insulation

 

 

Mold Inspection Journal: 3-26-09

Monday, March 30th, 2009

Case Study 09019: Did heating system failure cause mold in a flooded house?

Facts/History:

The owners of a two story Colonial were away on vacation for one month. When they returned home, they found the house flooded, on all levels. A failed component of the heating system caused the heat to turn off during a cold spell. Water and heat pipes froze and burst throughout the house causing extensive water damage; walls, ceilings, and floors were saturated. Water poured through central air conditioning system ductwork and recessed light fixtures. A professional flood response company was brought in immediately to remove wet belongings and building materials and to dry those that remained; drying holes were cut in the base of walls, Sheetrock and insulation was removed in certain areas, wall-to-wall carpeting and the finished basement floor was removed, and the interior of the house dried. Most personal belongings in the home were affected and had been removed (thrown away or cleaned and stored off-site) prior to our inspection; the house was completely empty.

Observations:

The finished basement sustained the most water damage. The basement ceiling was completely torn out, as well as some walls. The laminate flooring in the basement was also removed. Exposed fiberglass insulation remained in the furnace room ceiling. All baseboards were removed and drying holes made in the base of most walls in the house. The kitchen and finished garage were mostly ‘gutted’ because they took on so much water. No building materials were wet on the inspection day. Widespread water staining was noted on walls and ceilings. Hardwood flooring remained on the first floor and was badly warped and cupped; boards were separating and dark discoloration was noted in the seams. Bathroom tile floors remained on the second floor but linoleum floors on the first floor had been removed. Many sections of plywood sub-flooring were exposed and some water staining, but no visible mold, was present. There was no mold odor on the first or second floors and minimal visible mold was discovered on the base of two Sheetrock walls in the basement; a slight mold odor was detected in the basement.

Gutted kitchen

Gutted kitchen

Damaged hardwood floor and drying holes

Damaged hardwood floor and drying holes

Sampling Strategy:

GML was brought in to do a mold inspection to determine if the flooding caused mold growth on building materials. Sixteen surface mold samples were collected from remaining building materials and on all levels of the house, including in the garage. Hardwood flooring materials could not be tested without destroying boards, but the damage was clear. GML tested several different types of materials including Sheetrock, plywood, wall studs, and OSB sheathing in the kitchen to get representative samples of materials exposed to water.

Lab Results:

Three surface samples confirmed mold growth on remaining Sheetrock in the house. Two were from the basement and one from behind one of the second floor bathtubs. The predominant molds growing on the Sheetrock were Aspergillus, Penicillium, and the infamous toxic black mold, Stachybotrys. None of the other thirteen samples described mold growth.

Recommendations:

Professional mold remediation is needed to remove contaminated Sheetrock in several areas of the basement, and all hardwood flooring on the first floor. Based on our experience in similar situations and the onsite inspection, even without testing, the conclusion was made that the hardwood flooring is contaminated. The AC system will need to be professionally cleaned. Once all the work is completed, the whole house should be cleaned using specialized, detailed cleaning procedures.

Mold Inspection Journal: 2-17-09

Monday, March 30th, 2009

Case Study 09018: Attic Mold

Facts/History/Observations:

Single family, two story house was converted from a one level ranch originally built in the 1960’s. A recent home inspection discovered mold on the underside of both sides of the roof, mainly on plywood sheathing. Mold was also growing on both gable ends. The attic had a functioning ridge and soffit vent system as well as one open gable vent. The second floor bathroom fan was exhausting into a soffit vent. Mold was reportedly present when the current owner purchased the house at which time they added the ridge and soffit vent system with the new roof. The cause of the mold was inadequate ventilation prior to the installation of the ridge and soffit venting system. There were no other signs of water leaks or sources of accumulated moisture.

Mold on plywood roof sheathing

Mold on plywood roof sheathing

Inspection Strategy:

• Visual inspection
• Moisture readings in wood materials
• Surface tape-lift sample collected from plywood roof sheathing with black mold

Lab Results:

• Mold Identification: Actively growing Cladosporium
• Classification: Cladosporium is a common, environmental mold often found in attics when there is a moisture problem

Recommendations:

It is recommended to have the attic evaluated to confirm that there is adequate ventilation and to discuss insulation, the bathroom vent, the gable vent, and any other factors that can influence mold growth development. Professional mold remediation is necessary to remove the mold growth in the attic; a homeowner or otherwise unskilled person should not do the cleaning because of the risks involved with such a project. Proper containment and decontamination procedures are needed. All insulation should be removed from the floor of the attic. A sealant should be applied to wood materials as the final remediation step in this attic.

Mold Inspection Journal: 3-3-09

Wednesday, March 25th, 2009

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

rotted-plywood-beneath-stairs

-HVAC systems in disrepair

  • 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

mold-on-central-humidifier

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