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Context
A 12-unit Buffalo NY apartment building (1971-construction, central HVAC, two-story residential) where 4 unit tenants had filed habitability complaints over a 4-month period citing musty odors and visible mold growth in bathrooms and adjacent bedroom walls. The property management company had performed visual inspections in each unit and dispatched a remediation contractor twice. First to clean visible mold in one unit, then to a second unit. The complaints continued and expanded; the property manager retained us for independent multi-unit assessment.
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Methodology
Field visit covered 8 of 12 units (4 with active complaints + 4 control units without complaints). Thermal imaging in each unit; spore-trap air sampling in each affected unit + 4 unaffected controls + outdoor baseline; surface sampling at visible-growth points; bulk sampling of suspect drywall in 2 affected units; flow-rate measurements at HVAC supply registers in all 8 units; condensate-line inspection at the central HVAC equipment.
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Pattern identification
Affected units all shared a common HVAC supply-air branch, Building Branch B serving units 201, 202, 203, 204. Unaffected units were served by Branch A or Branch C. Thermal imaging at the central HVAC equipment revealed sustained condensate pooling at the Branch B condensate pan, with the condensate drain line partially blocked. The pooling moisture had been distributing into the Branch B supply ductwork over months, with the moisture and contamination delivered to the Branch B units while Branch A and C units remained unaffected.
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Lab findings
Branch B units air-sample results: Cladosporium 4,200-6,800 sec/m³ + Aspergillus/Penicillium 1,400-2,800 sec/m³ + occasional Stachybotrys detection. Branch A/C control units within outdoor baseline range. Surface samples in Branch B units confirmed active mold growth on bathroom drywall + adjacent bedroom walls. HVAC swab samples at Branch B supply registers confirmed mold colonies inside the ductwork.
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Remediation scope + execution
Our scope recommendation: HVAC condensate drain repair + condensate pan cleaning + Branch B duct cleaning + replacement of contaminated drywall in 4 affected units + post-remediation clearance. Recommended contractor selection from the property manager's vetted list. Remediation completed by a Buffalo PACNY-member contractor over 3 weeks at $28,400 total. We returned for clearance testing per ANSI/IICRC S520; all Branch B units cleared at outdoor-baseline-range spore counts.
