Luxury Residence — Category 3 Sewage Backflow
Independent re-scoping of a contractor's Cat 2 designation revealed widespread sewage contamination requiring a full Cat 3 protocol.
5,400 sq ft single-family residence. Owner-occupied. Initial contractor assigned Category 2 to a basement-level overflow event.
Mainline backflow during a regional storm. Standing water present for ~36 hours before extraction.
Visual inspection, moisture mapping, thermal imaging, and substrate sampling on Day 4 post-event.
Elevated moisture across 1,180 sq ft of carpet pad, baseboards, and lower 24" of drywall. Several wall cavities measured >25% MC.
Thermal differential confirmed wicking up sheetrock to a continuous height of 22–28 inches.
Surface total coliform and E. coli sampling collected on hard and porous substrates per IICRC S540 guidance.
AIHA-LAP laboratory confirmed coliform and E. coli presence on porous materials. Direct exam of bulk samples confirmed cellulose breakdown consistent with bacterial activity.
Findings reclassified the loss as Category 3 — sewage contamination requiring removal of all affected porous materials within the impact zone.
Full Cat 3 remediation protocol issued. Independent PRV scheduled prior to reconstruction.
Containment, negative pressure, full PPE, removal of affected porous materials, antimicrobial application, and PRV against pre-defined clearance criteria.
Initial categorization defines the entire scope. An independent assessment within 72 hours of the event prevents under-remediation and downstream health risk.