This article provides general educational information about why mold recurs in buildings and what that means for Charleston-area homes. It is not medical advice, legal advice, or a professional assessment of any specific property. The account of Charleston’s fire stations is summarized from a Live 5 News investigation and includes the City of Charleston’s stated positions; this article does not independently verify either side’s claims. For health concerns related to mold exposure, consult a healthcare provider.
Because remediation removes growth, and growth is the symptom. The moisture that fed it is the cause. EPA states that if the conditions causing mold growth are not corrected, the growth will recur. A May 2026 Live 5 News investigation into Charleston’s fire stations documented that pattern in public buildings: stations that were cleaned or renovated and later had mold reported again, and one station that was closed twice. In Lowcountry homes, mold that returns usually traces to one of five things: an active water source nobody fixed, humid outdoor air still getting in, an HVAC system that was left out of the scope, surface treatment in place of removal, or humidity control that changed after the work. If mold is back, the useful question is not who to hire to clean it again. It is where the water is coming from. Air Flow Solutions USA, a family-owned, fully insured company serving the Charleston area, handles the HVAC and ductwork side of that question and starts with an inspection.
On May 11, 2026, Live 5 Investigates published a report built on more than 700 emails obtained through a public records request. The report describes years of complaints from Charleston firefighters about mold, water leaks, and hot, humid conditions in the stations where they live during shifts.
Several findings are specific enough to learn from.
Two stations were temporarily closed. According to Live 5, the Charleston Fire Department has closed two stations since 2024 over positive mold tests. Station 12 was closed in December 2024 and again in April 2025. Station 9 was closed in November 2024 so its HVAC system could be replaced.
The complaints were widespread. Live 5 reported that conversations with firefighters, photos, and emails show mold concerns raised at 12 or more of the city’s 17 stations at some point since 2017.
Some problems were reported again after work was done. One 2023 email cited in the report said the fire marshal could still see and smell mold in a Station 19 bathroom after renovations. A 2021 email from a captain said leaks and mold at Station 9 had been reported repeatedly over two years and were getting worse.
An industrial hygienist named the pattern. A certified industrial hygienist interviewed for the report said that however well mold is removed, it will regrow if the water source is not fixed, and that mold returning after remediation should prompt a more serious look at exactly where it is and why it got there.
The city’s position. City officials told Live 5 that fire stations have a structural disadvantage. Apparatus bay doors open and close all day, drawing in warm, humid Lowcountry air that rises into the living quarters above, and they said this is common across the Southeast. The fire chief said no instance of toxic or black mold has been identified. The city said its contractor’s testing used several measures, including temperature, humidity, and microbial samples. The chief also said seven of the 17 firehouses have been renovated in the past eight years, with two more scheduled for 2026.
Key Fact: Live 5 News reported in May 2026 that mold concerns had been raised at 12 or more of Charleston’s 17 fire stations since 2017, and that Station 12 was closed for positive mold tests in December 2024 and again in April 2025.
This article is not about who is right in that dispute. It is about what the record shows regarding recurrence, because the same sequence plays out in houses on James Island, in West Ashley, and on the peninsula.
The department’s deputy chief gave Live 5 a station-by-station status list. Read alongside the emails, five entries each illustrate a different way mold persists or returns.
| Station | What Live 5 reported | The building lesson |
| Station 9, King Street | Years of leak and mold complaints. In late 2024 and early 2025 most of the HVAC system was replaced, the ductwork was cleaned, windows were sealed inside and out, insulation and ceiling tiles were replaced, and a new roof went on. | The eventual fix was a package: water entry, air leakage, equipment, and ducts addressed together. |
| Station 12, Old Towne Road | Closed for positive mold tests in December 2024 and again in April 2025. | A second closure four months after the first is what recurrence looks like. |
| Station 6, Cannon Street | Renovated in 2022. Humidity problems followed as designers balanced modern energy requirements in a historic building, with dehumidification adjustments continuing into last year. | Renovation can change how a building handles moisture. |
| Station 14, Memorial Drive | Opened in 2018. Roof problems soon led to water damage and mold, with full repairs completed in 2025. | A new building is not immune. One persistent leak is enough. |
| Station 19, Bees Ferry Road | A 2023 email said mold in a bathroom was still visible after renovation work. | “Renovated” and “resolved” are separate claims. |
Station 9 is the instructive one. For years the complaints produced partial responses. What the department finally lists is a roof, sealed windows, new insulation, a largely new HVAC system, and cleaned ductwork. That combination is close to what a building scientist would prescribe on day one: stop the water, stop the humid air, fix the equipment that manages moisture, then clean what was contaminated.
A roof leak, a plumbing drip inside a wall, a condensate line that overflows, groundwater under the house. If the material gets wet again, growth returns, often in the same spot and within weeks. EPA’s mold guide is built on this point: moisture control is the key to mold control.
The city’s bay-door explanation has an exact household equivalent. A vented crawl space admits humid air by design. Leaky return ducts in a crawl space or attic pull that air straight into the system. Gaps around plumbing and wiring let it rise into wall cavities. No liquid water is involved, which is why this cause is so often missed. The surfaces simply stay damp enough, for long enough, through a cooling season that runs about seven months in Charleston.
Under-house moisture is the most common version of this in the Lowcountry, and the durable fix is crawl space encapsulation creating a conditioned space beneath the home.
A remediation contractor removes contaminated drywall and treats framing. The air handler and ducts that served that room for months are not touched. EPA’s duct cleaning guidance is direct about the consequence: failing to clean one component of a contaminated system can re-contaminate the entire system. It also says that insulated ducts whose insulation has become wet or moldy cannot be effectively cleaned and should be removed and replaced.
Key Fact: EPA states that if insulated air ducts get wet or moldy, the insulation cannot be effectively cleaned and should be removed and replaced, and that if the conditions causing mold growth are not corrected, mold growth will recur.
How contamination moves from equipment into living space is explained in how HVAC mold can spread through the whole house.
Firefighters quoted by Live 5 described a habit of covering problems so they could no longer be seen. Homes get the same treatment: stain-blocking paint over a ceiling, a fogging treatment through the registers, an antimicrobial spray on duct liner.
EPA’s guidance on these practices is cautious. It says sealants should never be used on wet duct liner or to cover actively growing mold, that no biocides are registered for use on fiberglass duct board or fiberglass-lined ducts, and that research has not demonstrated the effectiveness of biocides in duct cleaning. The trade press has caught up with this. A September 2026 article in The ACHR News warned HVAC contractors that relying on antimicrobials or encapsulants in place of removing contaminated materials, or failing to correct the underlying humidity or drainage problem, can leave them responsible when growth returns.
Station 6 is the example. A renovation that tightens a building, changes its ventilation, or installs differently sized equipment changes how the building dries. EPA notes that an air conditioner too large for the space cycles on and off frequently and removes moisture poorly, especially in humid regions. A house can come out of a renovation or an HVAC replacement cooler, quieter, and damper than it went in.
| How it came back | Most likely reason | Who addresses it |
| Same spot, within weeks | 🔴 Active water source | Plumber, roofer, or whoever stops the water, then remediation |
| Musty smell when the system runs; spotting at registers | 🔴 HVAC equipment or ductwork not addressed | HVAC mold removal and duct work |
| Returns every summer, fades in winter | 🟡 Humid air infiltration, usually from the crawl space | Crawl space and duct sealing work |
| Returns after heavy rain or an unusually high tide | 🟡 Drainage or groundwater under the house | Drainage, crawl space |
| Appeared for the first time after a renovation or new HVAC system | 🟡 Changed humidity control | HVAC contractor: sizing, airflow, dehumidification |
| Faint staining through fresh paint | 🟡 Covered, not removed | Remediation with removal of affected material |
Three observations point toward the equipment and ductwork.
The smell follows the airflow. It appears when the blower starts and fades when it stops, and it is noticeable in rooms far from the original problem.
The growth is at the air’s exit points. Spotting on supply registers, on the ceiling around them, or on the inside face of the return grille.
The air handler tells the story. Standing water or slime in the drain pan, discolored insulation inside the cabinet, or visible growth on the coil housing.
EPA advises against running an HVAC system that you know or suspect is contaminated with mold. It also advises asking any service provider to show you the contamination they say is there, and notes that a laboratory can confirm from a tape sample whether a substance is mold for roughly $50.
The specific things to look for at each of those points are listed in the signs that reveal mold in an HVAC system.
Where the equipment is confirmed as the source, the work required is biological contamination removal addressing HVAC equipment and the spaces it serves.
When mold has come back once, the second scope of work should look different from the first. EPA’s guidance and the ANSI/IICRC S520 remediation standard both rest on the same order of operations: correct the moisture, remove what cannot be cleaned, clean what can, verify.
| ✅ Scope that tends to hold | ❌ Scope that tends to fail |
| Names the moisture source in writing and says who will fix it | Describes cleaning only |
| Includes the air handler, coil, drain pan, and ducts serving the affected area | Stops at the wall or ceiling |
| Removes wet or moldy porous materials, including duct insulation | Sprays, fogs, or paints over them |
| Uses containment so work in one area does not spread debris to others | Open demolition with the HVAC running |
| Records humidity readings before and after | No measurements |
| Shows you the contamination and the finished surfaces | Asks you to take it on trust |
| States what is excluded | Implies everything is covered |
A word on testing. The hygienist in the Live 5 report argued that comparing indoor and outdoor airborne spore counts is not a reliable measure of contamination, and that the meaningful measure is how much material is affected. The city responded that the comparison was one of several metrics it used. EPA’s own guidance leans toward the practical view: in most cases, if visible mold growth is present, sampling is unnecessary, and there are no federal limits for mold or mold spores against which a result can be judged. For a homeowner, a clean air test after remediation is weaker evidence than a dry moisture reading and a corrected leak.
Air Flow Solutions USA applies the left-hand column to the part of the job it performs. Its inspections cover the air handler, coil, drain pan, and ductwork, findings are shown to the homeowner, and the estimate is written before work starts. Those are verifiable steps, and they are the ones this article recommends demanding from anyone.
The sequence of a properly scoped job is described in what HVAC mold removal involves and how the process works.
The cooling season is long. Systems here run roughly seven months of the year, so coils and drain pans spend most of the year wet.
The buildings are old, and they have been altered. Station 6 sits in a historic building, and the department attributes its post-renovation humidity trouble to reconciling modern energy requirements with that structure. Peninsula houses have been through the same thing: piers enclosed, ducts added beneath floors, windows tightened, all in buildings designed to breathe.
Water comes from below as well as above. Charleston’s king tides push the harbor to seven feet or more several times a year. The South Carolina Department of Environmental Services lists three more predicted king tide periods for 2026: October 10–11, October 26–29, and November 24–27. A crawl space that takes on water during those periods re-wets framing and duct insulation that may have been cleaned in the spring.
Nobody is licensed to do this work. South Carolina does not currently license or certify mold assessors or remediators. A bill introduced in February 2026, H.5109, would create a certification program, and it was referred to a House committee with no further action recorded. Until that changes, the scope of work in your hand is the only quality control there is.
| Charleston condition | What it re-wets | Timing |
| 🔴 King tide or storm water in the crawl space | Subfloor framing, duct insulation, low-mounted equipment | Predicted dates each fall; any heavy rain at high tide |
| 🔴 Seven-month cooling season | Coil, drain pan, supply plenum | Roughly April through October |
| 🟡 Enclosed piers and vented crawl spaces | Floor system and anything running through it | All summer |
| 🟡 Renovation in historic structures | Wall cavities and ceilings that used to dry on their own | After the work, often the first full summer |
| 🟢 Winter | Little | The practical window for non-urgent work |
This needs saying plainly. EPA’s position is that duct cleaning has never been shown to actually prevent health problems, and that it should be done only as needed. Cleaning ducts will not stop mold from returning if the roof still leaks or the crawl space is still wet. Done before the moisture is fixed, it is money spent twice.
Duct work belongs in the scope when the system has been part of the problem: visible growth on hard duct surfaces or components, insulation that got wet, or a system that ran throughout a remediation without protection. In those cases the appropriate step is comprehensive cleaning of the home’s air distribution system, in sequence, after source correction.
What that process consists of, and what it does not include, is set out in what air duct cleaning is and how the process works.
How to check afterward that it was done properly is covered in the warning signs that an air duct cleaning was done poorly.
Because the moisture that caused it was not corrected. EPA states that if the conditions causing mold growth are not fixed, the growth will recur. Remediation removes contaminated material. It does not repair a leak, dry a crawl space, or change how the air conditioning handles humidity.
If a material gets wet again, EPA’s guidance is that mold can begin growing when materials are not dried within 24 to 48 hours. Where the cause is humid air and not liquid water, the return is slower and tends to follow the season, showing up in the first humid months after the work.
Yes. EPA notes that failing to clean a component of a contaminated HVAC system can result in re-contamination of the entire system, and that the duct system can distribute contaminants through a home. If the equipment and ducts served the affected area and were not part of the scope, they are a likely reservoir.
No. EPA says sealants should never be used on wet duct liner or to cover actively growing mold, and that no biocides are registered for use on fiberglass duct board or fiberglass-lined ducts. Coating a surface hides growth without removing it or the moisture behind it.
It can be one piece of evidence, but it is not proof on its own. EPA says sampling is usually unnecessary when visible growth is present, and there are no federal limits for mold spores to compare a result against. Dry moisture readings, a documented repair of the water source, and visibly clean surfaces are stronger indicators.
The conditions favor it. The cooling season runs about seven months, many houses sit over vented or enclosed crawl spaces, tidal flooding re-wets the space under homes several times a year, and much of the housing stock has been renovated in ways that changed how it dries.
That depends on the written scope of work and is a legal question for an attorney. In practical terms, a contract that covered only cleaning leaves the moisture source with the owner. This is the reason to insist that the moisture source be named in writing before work begins.
Choose a company that inspects the air handler, coil, drain pan, and ducts, shows you what it finds, replaces wet or moldy duct insulation instead of coating it, and puts the scope in writing. Air Flow Solutions USA is a family-owned, fully insured company serving the Charleston area whose services include HVAC mold removal, air duct cleaning, and crawl space work. It can be reached at (843) 864-4649.
When mold comes back after remediation in Charleston, the first job was usually incomplete in a specific and identifiable way. The fire station record shows each version: a leak that kept leaking, humid air that kept arriving, a renovation that changed the building, and a system that was only fully addressed after years of partial fixes. The station that finally received the full package of roof, envelope, equipment, and ductwork is the one worth copying.
For a homeowner the order is the same. Find the water. Stop it. Remove what cannot be cleaned. Clean the rest, including the HVAC system if it was involved. Then confirm the space is dry. Any company proposing to skip the first step is selling the same job a second time.
Charleston-area homeowners can reach Air Flow Solutions USA at (843) 864-4649 or info@airflowsolutionsusa.com, Monday–Saturday 8am–8pm and Sunday 8am–2pm.
This article is for general informational purposes only and does not constitute medical advice, legal advice, or a professional assessment. Consult qualified professionals about your specific situation.
Sources and Authoritative References
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