12 guides
Mold: what it means and what to do
You found mold. What it is, whether it is dangerous, how much of it you can deal with yourself, what remediation actually involves, and what a policy will pay for.
You have just found it
What it is, what it means, and what to do today.
- You found mold Find the water before you clean the mold. Mold is the symptom of a moisture source that is still there, and cleaning the surface without finding the leak means doing it again in a month.
- Is black mold dangerous? Color does not identify a species and does not tell you the risk. The specific claims made about toxic black mold are not well supported, but all indoor mold is removed the same way regardless, so the question rarely changes what you do.
- Mold, mildew, or dirt? Wipe a small patch with detergent and look again in a week. Dirt and soot come off and stay off, surface mildew comes off and returns, and mold that has gone into the material does not come off at all.
- Mold behind a wall A musty smell with nothing visible, staining that comes back after painting, or a wall that is cool and slightly soft to the touch. Before opening anything, check the humidity and use a moisture meter on the wall itself.
Getting rid of it
How much you can handle yourself, and what needs containment.
- Do you need a test? Usually not. If you can see it or smell it, you already know it is there, and the species does not change the work: remove it and fix the water. Testing is worth paying for in a small number of specific situations.
- Can you remove it yourself? The usual threshold is about ten square feet on a hard or replaceable surface, with the water source fixed. Past that, or inside the building fabric, it needs containment because disturbing it is what spreads it.
- Mold in a bathroom Run the exhaust fan for twenty minutes after every shower, not during it only. Bathroom mold is almost always condensation rather than a leak, which means ventilation fixes it and cleaning does not.
- Mold under a floor Lift a corner and look at the underside and the subfloor rather than the surface. Water spreads sideways under a floating floor with nowhere to escape, so what you can see is always smaller than what is wet.
- Stopping it coming back Get indoor humidity under about 50 percent and keep it there. Mold needs moisture, food, and time, and moisture is the only one of the three you control, so a hygrometer is worth more than any spray.
Insurance and cost
What a policy will pay for, and what removal actually costs.
- Does insurance cover mold? Usually only when it follows directly from a covered water event that you reported and dealt with promptly, and usually up to a low separate limit. Mold from a slow leak or from humidity is excluded almost everywhere.
- Mold in a rental Report it in writing the day you see it, with photographs. Structural damp and leaks are the landlord's to repair; condensation from how a place is ventilated is where it gets argued, and the written record decides it.
- What removal costs Ask for it as three numbers: finding and fixing the water, the remediation itself, and the rebuild. The remediation is priced by contained area and by how much material comes out, not by how much mold you can see.