Call a professional when the growth is in the material rather than on it — drywall, ceiling texture, insulation, carpet pad, the inside of an air handler — or when the water feeding it has not stopped. Film sitting on tile, sound grout, caulk, glass or a vent cover is still a cleaning job.
Almost everything written about this question answers it with a square-footage rule. We are not going to repeat it: it is not a figure this site publishes, and it measures the least decisive thing in the room. In a Miami house, the patch you can see is the small part of the answer.
The two tests that actually decide it
1. Is it on the finish, or in the material?
This is the line, and it has nothing to do with size. What decides it is the porosity of whatever is underneath.
- Sits on top — still cleaning. Glazed tile, glass, sealed stone, a fiberglass tub surround, a metal or plastic vent cover, a window track, sound painted trim. The colony has nothing to grow into, so it comes off the way any other film comes off.
- Grows in — not cleaning any more. The paper face of drywall, popcorn or knockdown ceiling texture, grout that has gone soft, a caulk bead black all the way through, the particleboard floor of a sink cabinet, insulation, carpet pad, the lining inside a duct. Wiping these cleans the top of something colonised underneath.
Two quick ways to tell which column you are in. First, wipe a small area with a damp cloth: if the mark lifts and the surface underneath is its original colour, it was on top. If it lightens but a shadow stays in the material, it is in. Second, press it with a thumb. Drywall that gives, a soft cabinet floor, ceiling texture that crumbles — that material has already taken water, and cleaning it is cosmetics.
2. Has the water stopped?
If you can name the source — the leak that has been repaired, the caulk bead that failed and was replaced, the laundry that was drying indoors — then cleaning makes sense, because you are cleaning something that has finished happening. If you cannot name it, what you are scheduling is a repaint six months out. And here the source is often not a leak at all. It is condensation.
“Mold isn’t the problem. It’s the receipt for the problem. If the water is still arriving, cleaning only tears up the receipt.”
What Miami changes about the answer
The A/C is the dehumidifier, and it runs twelve months
In a dry climate the air conditioning is off for half the year. Here it is not, which makes the system the thing that governs the whole house’s humidity. That is why black speckling in a ring around a ceiling register is almost never a dirty register: it is cold air meeting metal and meeting the room’s damp air. It is a humidity and airflow question, not a wiping question. We clean the vent cover — it is on the published list. What is behind it we do not open.
It is also behind the most common way a Miami apartment goes wrong: closing it up for the summer with the A/C off. Seasonal residents and hosts between seasons both do it to save money, and both come back in October to something that is no longer a cleaning problem. If the unit is going to sit empty, it sits with the air running.
The wet season and hurricane season are two different calendars
The rainy half of the year runs roughly May into October: nothing finishes drying between downpours. Hurricane season runs June through November and does something different — it seals the house. Windows shut for weeks, shutters up, sometimes no power and therefore no air conditioning. What decides the question afterwards is not how big the mark is but whether the material got dry again. If it stayed wet, wiping it is cosmetic.
Salt air keeps wet exactly what you need dry
Near the water there is one more factor: salt is hygroscopic — it pulls moisture out of the air and holds it against the surface, as we explain in cleaning green algae off lanai screens. On the barrier islands and along the bay, a salt film on tracks, frames and railings stretches every damp spell out. It does not call for a stronger product; it calls for rinsing more often.
There are no basements here, so look at the cold spots
Almost everything here is slab-on-grade block, so the imported advice to check the basement has nothing to check. The local equivalent is elsewhere: the exterior wall behind a headboard or a sofa, the back corner of a closet on an outside wall, the inside face of a block wall in a 1950s house. Air does not move there and the wall runs cooler than the room. That is where it shows up first.
In a condo, the decision may not be yours to make
Before you hire anybody, read the declaration. The wall cavity, the riser running behind it and the building envelope may not be yours, and if the water is arriving from there, the correct move is to report it rather than solve it privately. Then there is access: buildings want vendors registered at the front desk, and many associations require a certificate of insurance on file before a crew gets past the lobby — we cover that in the apartment and condo guide, along with service elevators assigned by reservation and quiet hours.
If you rent, tell the owner in writing before you clean it. Not for a legal reason we are qualified to explain, but for a practical one: a wiped wall is a wall with no record of what happened. And if the building asks for paperwork on whoever comes in, ours is published — $2,000,000 general liability coverage, every cleaner background-checked, and the certificate requested by email with “COI” in the subject and the entity name; most return within 2 business hours.
Where we stop, in our Terms’ own words
JAS does not sell mold testing and does not sell remediation, and saying so costs us less than disappointing you. Our Terms put it plainly: we reserve the right to refuse or stop service where conditions are unsafe for our team — such as mold, infestation, biohazards, or abusive behavior. If we stop early for safety, a partial refund applies for the unworked portion.
What we do book is the other half, the half that comes afterwards: once the water is settled and the material is sound, a deep clean is what brings the surfaces back. From its published checklist, these are the items this subject actually touches:
- Grout spot-treatment
- Air vent covers
- Window sills + tracks
- Baseboards hand-wiped
- Door + frame edges
- Cobweb sweep (corners)
Appliance interiors and windows are priced separately, and that too is published on the same page. The rhythm is that page’s call rather than ours: most Miami homes benefit from a deep clean two to three times a year, because humidity, salt air, and year-round pollen mean buildup happens faster here than in drier climates. When the starting point is moisture, that cadence stops being a suggestion and becomes maintenance.
Quick answers
Can a cleaning service remove mold, or do I need remediation?
A cleaning service can remove what is sitting on a hard, non-porous surface — tile, glass, a vent cover, grout that is still sound. It cannot remove what has grown into drywall, ceiling texture, insulation or a duct lining, because at that point the work is taking material out and putting new material in, which is a different trade with different credentials. JAS books neither testing nor remediation.
How much mold is too much to clean myself?
We are not going to give you a square-footage number. It is not a figure this site publishes, and it measures the wrong thing anyway: the size of the patch you can see. The honest version is that it is too much when the growth is in a porous material rather than on a finish, when you cannot name the water that caused it, or when it comes back in the same place after you have cleaned it properly.
Is bleach the right thing to use on it?
On a hard, non-porous surface it is one option among several. On drywall, ceiling texture or crumbling grout it whitens the face without reaching what is under it, which is exactly why the spot looks solved and returns. And never combine bleach with vinegar or with an ammonia cleaner — that mix makes toxic gas — least of all in a shut bathroom with the fan off.
It keeps coming back on the same bathroom ceiling. Why?
Because the thing that needs fixing there is usually not the cleaning. A ceiling that regrows is telling you the moisture landing on it is not leaving: an exhaust fan that runs for a minute after the shower instead of well past it, a door kept shut so the wet air has nowhere to go, or cold supply air crossing a damp ceiling. Change the airflow and the spot stops being a recurring cleaning task.
If I book a deep clean, will you clean it?
Surface film on tile, glass, sound grout, caulk or a vent cover is inside a deep clean’s normal scope — grout spot-treatment and air vent covers are both on the published 42-item list. What we will not do is clean over growth in drywall, ceiling texture or insulation, and our Terms let us stop when conditions are unsafe for the team; if we stop early for safety, a partial refund applies for the unworked portion.
The short version
On a non-porous finish with the water already dealt with: clean it. In the material, or with the water still arriving: call someone, and not a cleaning company. In Miami the variable that decides most is not the size of the patch — it is the air conditioning, the house sealed up through hurricane season, and salt air that will not let anything dry. We come in afterwards, when what is left is a surface.
This guide is part of the JAS operating playbook — including the part where we withhold the number everyone else copies, because it is not ours to publish.