Moisture and Mold in a Tenant Improvement
The Problem
 During
tenant improvement renovations at a commercial office building
located in Buffalo Grove, Illinois, the general contractor
discovered mold growth in several locations in the building. The
tenant contacted Chelsea Group to conduct a visual observation of
the facility with special consideration to areas with reported
biological growth, perimeter spaces, and the exterior building
envelope.
The facility is a 62,000 square foot, two-story facility
functioning as both laboratory and office space. Many of the office
areas in the building were wallpapered, and the tenant wanted to
limit the amount of destructive testing. The Chelsea team used
infrared thermography to limit the damage to building materials.
The purpose of the assessment was to observe the conditions at
the property and determine the extent of biologically impacted
building materials and the potential sources of water intrusion. In
addition to visual observations, a sampling protocol was conducted
to determine whether the indoor air quality and HVAC systems had
been affected by the mold growth. Finally, based on the findings,
Chelsea Group provided recommendations regarding proper cleaning and
removal techniques and further investigation where necessary.
Chelsea Group Intervention
Interior Inspection
 Chelsea
Group conducted a visual observation of the interior space of the
building that was documented with digital photographs. In addition,
infrared photographs were taken to determine the surface
temperatures of exterior walls and columns, which can often indicate
moisture intrusion.
In this initial inspection, suspected biological growth was
observed along the base drywall of areas under renovation, in
addition to some water stained ceiling tiles. Chelsea Group
recommended that window caulking and flashing be inspected from the
exterior to rule out potential pathways of water intrusion.
Immediate results: The majority of biological growth
was contained to the areas where renovation was taking place,
which were already under containment to reduce construction
debris, putting the tenants at ease.
Using a moisture meter, a moisture survey of the porous and
semi-porous building materials of the facility was conducted where
water staining was observed and at random exterior locations.
Temperature, relative humidity, and dew point measurements were also
taken. The presence of moisture does not necessarily indicate mold
growth, but does indicate the potential for it.
Immediate results: Some slight indications of
potential moisture were noted in exterior building materials;
however, for the most part no elevated moisture levels were
registered. Further investigative techniques were necessary.
 Many
of the office areas in the building were wallpapered, and the tenant
wanted to limit the amount of destructive testing. The Chelsea team
used infrared thermography to determine the surface temperatures of
exterior walls and columns, which often indicate moisture intrusion.
This was especially helpful on wallcovered exterior walls, and also
in areas that were inaccessible due to furniture storage.
In some areas along base drywall, suspected biological growth was
observed. Although elevated moisture levels did not register on the
moisture meter, thermal differences were observed in the infrared
thermograph.
Immediate results: Infrared thermographs identified
potential moisture in several areas where no mold growth was
visually observed or registered by moisture meters.
Sampling Protocol
Based on the initial site assessment of the facility conducted by
the Chelsea team, a biological sampling strategy was developed to
evaluate whether and to what extent any type of microbial (fungal)
amplification from the HVAC system was dispersed through the
building. The interiors of all of the air handlers were visually
inspected for potential microbial growth.
Surface tape-lift samples were collected in the air handling
systems to distinguish between settled mold spores, normal in a
typical environment, versus amplification. The samples were
collected on the downstream side of the cooling coil and on the
fiberglass insulation of the fan cabinets.
Airborne spore-trap samples were also collected to determine the
source amplification effect on the indoor air quality. The air
samples helped to deduce if spores from surface growth were being
distributed to non-impacted areas through the air distribution
system because of the open-plenum nature of the ventilation system.
All of the samples were processed by an AIHA accredited
environmental microbiology laboratory.
No overt biological growth was observed in the air handling
systems. All other areas in which airborne samples were collected
did not indicate the spread of the discovered indoor amplification
to other non-renovation areas at the time of the sampling. The
concentrations and types of spores from the indoor samples were
comparable to outdoor baselines and to non-impacted interior
controls.
 Immediate
results: Although no overt biological growth was found in the
air handling systems, during the sampling protocol Chelsea Group
found some other mechanical concerns:
- Gaps existed between individual filters, and the end caps of
the filter racks were missing, allowing particulate build-up on
cooling coils, which can lead to increased energy usage.
- The cooling coils and condensate pans were dry at the time,
but rusting of the condensate pans was noted. Standing water
during the cooling season has the potential to support
biological growth.
Exterior Inspection
 The
Chelsea team carried out an exterior building envelope inspection,
with attention to the waterproofing systems of windows and
structural columns. A brief walk-around of the building’s perimeter
was conducted to observe any conditions that may be conducive to
water intrusion.
At the time of the site-assessment, water was observed streaming
off the roof in sections where sloped roof lines meet. Snow and ice
build-up was observed where the two roof lines meet. The building
exterior at these areas was water stained, and water was observed
pooling near the foundation in some of these areas. In addition, a
small gutter system with a heater was observed in two locations to
combat the ice damming issues that were reported by the Lead
Engineer. Again, water was observed flowing over these drainage
systems, down the side of the building.
Landscaping around the building perimeter was sloped towards the
building in several locations. In addition, there were areas where
the landscaping covered the bottom window flashing and weep holes.
These conditions can lead to water intrusion through the building
envelope. Some landscaping sprinkler heads were closely positioned
to the building exterior, which may be an additional source of water
during the spring and summer months.
Waterproofing systems, specifically exterior caulking of the
second floor, were not easily accessible. The property managers
indicated that plans to re-caulk the building exterior were part of
that year’s capital planning budget.
Immediate results: Chelsea Group recommended:
- Investigate options for proper roof watershed systems to
direct rain and melting snow off the roof away from the
foundation of the building.
- Re-landscape areas that currently slope towards the
foundation of the building to reduce potential of water
intrusion.
- Re-locate landscaping sprinklers that spray water on the
building.
Final Results
Following Chelsea Group’s careful planning, the discovered
moisture and limited biological growth did not significantly slow
the renovation schedule:
- Customized moisture mapping and infrared thermography
identified the interior affected areas.
- The integration of building sciences helped identify
potential water infiltration points and solutions for proper
management of watershed from the roof and landscaping systems.
- A thorough plan effectively guided remediation work.
- Bioaerosol sampling provided verification of proper handling
of mold removal and no further active mold growth.
- The tenants were assured of an acceptable indoor environment
for the building occupants.
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