Cambridge experiences humid summers where outdoor relative humidity routinely exceeds 70%, accelerating mold growth in older building envelopes. Ice dams repeatedly force meltwater under shingles into attic spaces each winter. The city's combined sewer system, dating to the nineteenth century, surcharges during intense storms and forces sewer-laden water into basement drains. Delay allows colonies to spread.
Cambridge's Victorian triple-deckers and brick walk-ups were built before modern vapor barriers. Fieldstone and brick foundations wick groundwater during spring snowmelt. HVAC equipment and basement framing that become contaminated do not self-remediate; the problem only grows.
Massachusetts has no standalone mold license, but contractors must comply with IICRC S520 protocols and carry general liability and workers' compensation insurance. Clearance testing must be performed by an independent industrial hygienist, not the remediation firm. Verify credentials before work begins and call 24/7 now.