Mold after a flood grows where moisture stays in wall cavities, subfloors and insulation, so drying has to reach those spaces and not only the visible surfaces. Progress is shown by moisture readings taken at the same points on each visit. Ask for a professional assessment when growth is large, inside a wall or under a floor, or returns after cleaning.
Key takeaways
- Mold needs moisture, and a flood leaves moisture inside walls, under floors and in insulation where nobody sees it.
- A surface that looks dry can still hold moisture in the cavity behind it, so readings matter more than appearance.
- Drying is measured in readings, taken at the same points on each visit, and it is finished when those readings return to the dry reference.
- Porous material with growth or a persistent smell is removed, because cleaning does not reach it.
- Ask for a professional assessment when growth covers a large area, is inside a cavity, or comes back after cleaning.
- Keep the readings, photographs and logs, because they show what was wet, for how long, and how it was dried.
Why does mold follow a flood?
Mold needs moisture, a food source and time, and a flood supplies the moisture in places that are slow to dry. Wall cavities, subfloors and insulation can stay damp long after the room looks dry, and that is where growth starts.
The materials in a building that hold water longest are the ones that are hardest to see: the inside of a wall, the underside of a subfloor and insulation that has soaked up water. A room can look dry while the framing behind its wall still holds moisture, and the growth that follows is often found by smell first.
A flood raises the moisture in a building across many spaces at once. The job of drying is to bring every one of those spaces back to a dry reference, not just the floor the owner can see.
How is drying measured?
Drying is measured with moisture readings in the floor, the wall and the framing, compared with a dry reference taken from an unaffected part of the building. The drying is finished when every layer returns to that reference.
The crew records readings at the same points on each visit, so the trend is clear. A reading that falls steadily shows that the drying is working. A reading that stops falling means something has to change, such as the equipment placement, the airflow or the source of the moisture.
The owner should receive the readings with the locations and the dates. Those numbers show what was wet and for how long, and they are the evidence for any decision about removal or replacement.
| Reading pattern | What it suggests | What the crew does |
|---|---|---|
| Falling steadily toward the dry reference | The drying is working | Continues the plan and reads again |
| Flat across several visits | Moisture is staying in the material | Changes airflow or opens the cavity |
| Rising again after drying | A source may still be open | Looks for a leak or a route for water |
| High at the wall base only | Water wicked up from the floor | Opens the lowest section of the wall |
| Dry in the room, wet in the cavity | Surface drying is not enough | Checks the cavity before closing it |
What is done to wall cavities?
Where readings stay high inside a wall, the crew opens a small section to let air reach the framing and the insulation. Soaked insulation is removed, the cavity is dried in place, and the opening is photographed before it is closed.
A cavity opening is kept as small as the readings allow. The crew looks for growth, notes the condition of the framing and measures the moisture in the wood. Framing that is sound is dried in place, and insulation that is soaked is removed because it cannot be cleaned to a safe standard.
Once the cavity reads dry, the wall can be closed. The owner receives the photographs and readings of the opening, which show exactly what was found and what was done.
When should I ask for a professional mold assessment?
Ask for a professional assessment when growth covers a large area, is found inside a wall or under a floor, returns after cleaning, or when the building has a strong smell that the drying has not cleared. An assessment gives the owner an independent check of the work.
An assessment is a separate step from the cleanup. It looks at the extent of the growth, the moisture in the spaces around it and whether the drying has reached them. The owner can ask for the assessment in writing and for the report to be given to them.
Ask any company that offers mold work to show its credentials in writing, and check any license it names with the Louisiana State Licensing Board for Contractors where a license applies to the work. This guide does not state a mold license category.
What should I do before anyone opens a wall?
Photograph the area and any smell or stain, keep the room closed off from the rest of the house, and do not open or tear out the wall yourself. Disturbing growth spreads spores into the air, so the first opening should be made by the crew with protection in place.
Closing the door of the room and sealing the gap at the bottom helps keep the air contained. Keep children, older adults and anyone with breathing problems out of the room. If you must enter, wear a fitted mask, gloves and eye protection.
Write down the date the water was found, the date it was reported dry and any smell you noticed. Those dates help the crew plan the readings, and they help an assessor understand the moisture history.
What can I clean myself, and what should I leave?
You can wipe a hard, non-porous surface with a suitable cleaner once the area is dry and the room is ventilated. Porous material, such as drywall, insulation and carpet with growth, should not be cleaned. It should be assessed and removed.
Do not mix cleaning products, and do not use bleach with ammonia or other chemicals. A vacuum used on growth should have a HEPA filter, and it should be emptied outdoors or into a sealed bag.
Growth on framing or subfloor is a judgment for the crew. Some surfaces can be cleaned and dried, and others need to be removed. The crew explains the decision and records it.
How does drying end, and what proves it?
Drying ends when the moisture in every layer of the building returns to the dry reference. The proof is the set of readings from the last visit, the photographs of each area and the final report, which the owner keeps.
The equipment is removed only after the readings show the building is dry. A final check of the rooms and the cavities confirms it, and the crew records the last readings with their locations.
A building that is dry at the end of the work can still show signs of the flood, such as stains or repairs to finish. Those are separate from the drying and are discussed with the owner before any repair starts.
Ask for a re-check of the same points after the equipment comes out, if the building has been closed up in the meantime. A closed house can take on moisture again in humid weather, and a second set of readings shows whether the dry result has held. The crew can schedule that check and record it in the same file.
Who should be present at a mold assessment?
The owner should be present or represented, and the assessor should explain what is being looked at and why. The crew that did the drying should be available to answer questions about the readings and the openings it made.
Being present lets the owner see the openings, the readings and the framing for themselves. It also lets the owner ask questions as they arise, which is more useful than reading a report afterward. If the owner cannot attend, a trusted representative should be there and should receive the photographs.
The assessment report should describe the areas looked at, the method used, the readings and the conclusions, and it should say what was not checked. A report that does not state its limits is harder to rely on.
How do I plan the work around a mold finding?
Plan the removal and the drying together, keep the affected rooms closed off, and schedule the re-check before the rooms are closed up again. Ask the crew to put the sequence in writing, so each step is known before it starts.
A mold finding changes the sequence of the work. Removal of porous material comes first, then cleaning of the framing, then drying, and then the re-check. Each step needs its own readings, so the plan should show where the checks fall.
Keep the affected area sealed while the work goes on, and keep the air moving in the direction the crew advises. Do not close the wall until the re-check has been passed, and record the date on which it was passed.
Frequently asked questions
How do I know if the mold is inside the wall?
A musty smell with no visible growth in the room, a damp feel in one area of the wall, or paint that bubbles in one patch can point to growth inside. The crew reads the wall and opens a small section to confirm.
Can the crew clean mold off the framing?
Framing that is sound can often be cleaned and dried. Deep or heavy growth may need more work, and the crew explains what it finds before it does more.
Will the mold come back?
It can, if moisture is still reaching the cavity or the source is not closed. The readings on the last visit show whether the building is dry, and a later check can catch a return early.
Is a professional assessment the same as the cleanup?
No. An assessment looks at the extent of the growth and whether the drying has reached it. The cleanup removes the material and dries the structure. An owner can ask for either, or both.
Does a mold test replace the drying?
No. A test tells you what is present, but the moisture still has to be removed and the material that cannot be cleaned still has to come out. The drying is what solves the problem.
Should I stay in the house while the mold is treated?
It depends on how large the area is and where it is. For a small area, the rest of the house may stay in use. For larger work, the crew explains which rooms should stay closed and for how long. Ask the crew to write down which rooms stay closed, which air returns are sealed and when each room can be reopened, so that the household has the plan in writing as well as in conversation.
Sources
This guide is general information for Lafayette Parish homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.