The patch you can see is often not the whole problem. Four issues account for most of what people run into after the first cleanup or the first company visit.
The four recurring issues
All four trace back to one thing the EPA puts first in its guidance: fix the source of the water or leak. Mould removed without correcting the moisture behind it grows back, which is why a second visit is so often a drying problem rather than a cleaning one.
Each of these has a different fix, which is why identifying which one you have matters.
Growth comes back after cleaning
1- Almost always means the moisture source was never actually fixed, not that the cleaning itself failed
Ask any company what they are doing about the source, not just the visible growth.
Growth behind walls or under flooring
1- Suspected from a persistent smell or a discoloured area with no clear surface cause, and typically requires opening up the space to confirm
This is where a professional inspection earns its cost - a surface cleaning cannot reach what it cannot see.
The moisture problem itself is never addressed
1- A leaking pipe, failed grout, poor grading around the foundation, or inadequate ventilation left as-is after remediation
This is the single most common reason a remediated area needs remediating again.
Landlord, tenant or insurance disagreements
1- Who is responsible for fixing the source versus the growth, and whether an insurance policy covers either, varies by lease, by state and by policy
This is not something a general reference page can settle - it depends on your specific lease, policy and state.
