Mold grows on wet building materials that stay wet for long enough, so the most effective step after a water loss is drying the materials to their goal. This guide explains how growth starts, what to look for, what testing can and cannot tell an owner, and the questions to ask before any removal begins.
Key takeaways
- Mold needs moisture and a food source such as paper, wood, pad or dust, and drying removes the moisture.
- A material that dries within the plan rarely grows mold, while one closed up while damp often does.
- Visible growth, a musty smell and a stain that comes back are the signs to act on.
- Testing answers a specific question and does not replace the readings.
- This site does not name a licence for mold work or claim one for this business, so the owner should ask who does the work and what paperwork covers it.
- Porous material that has grown mold is usually removed, and hard surfaces are cleaned and dried.
How does mold start after a water loss?
Mold spores are always present, and they grow when a damp material gives them moisture and something to feed on. The time it takes depends on the material, the warmth and how long the wet lasts.
Paper, cardboard, wood, carpet pad and the paper face of drywall are the materials that feed mold most readily. Concrete and masonry do not feed it, but the dust and the finish on them can, and a wall above them can hold moisture for long enough to support growth.
The practical point is that drying is the main defense. Growth needs wet material, and once the material is dry the conditions for growth are gone, even if the spores are still present. That is why the drying plan is set on readings rather than on how the room looks.
What does mold look like in a Hammond house?
Mold can be black, green, gray or white, and it can look like a stain, a fuzz or a film. The smell is often the first clue, and it is most noticeable in a closed room.
A musty smell in a basement, a closet or behind a bookcase on an outside wall is the most common early sign. A dark or fuzzy patch on the lower wall, the back of a baseboard or the underside of a carpet is the next sign, and a stain that returns after cleaning and painting is the one to act on.
Mold behind a finish is harder to see. A wall that is cool and damp to the touch near the floor, or a floor that feels soft over a crawl space, can hide growth in the cavity. The readings and the openings show what is behind the finish.
What does drying prevent, and what does it not?
Drying stops growth from getting started or continuing. It does not clean up growth that has already begun, and that is handled separately.
A material that is dried to its goal within the plan rarely grows mold afterwards. That is the most useful outcome of the drying, and the readings are the evidence of it. The owner should keep the readings with the restoration file.
Drying does not remove mold that has already grown on porous material. That material is usually removed, and hard surfaces that show growth are cleaned, dried and checked again.
When is testing useful, and what does it tell you?
Testing is useful when the owner needs to know what is in a particular area, or when the question is whether a wall that is staying is safe. It does not tell the owner the whole story, and a clean result does not mean the material is dry.
A test answers a specific question: what is in the air or on this surface, and how does it compare with a reference. It is a snapshot of one place at one time, and it does not replace the readings or the inspection.
Where a test is wanted, the owner should ask who takes the sample, who analyzes it and what paperwork covers that work. The results should be given in writing and kept with the restoration file, along with the readings that show the material was dried.
Who does the work, and what paperwork covers it?
This site does not name a licence for mold work and does not claim one for this business. The question to ask any company is who will do the assessment and removal, and what paperwork covers that person for the work in front of you.
Requirements for mold assessment and removal can change, and they should be checked with the state and the local building department rather than taken from a website. A company that cannot say what covers its mold work should be asked to put that in writing before the work begins.
The restoration record should name the work that was done and the person who did it. A record that says only that mold was treated, with no name and no readings, is not enough to protect the owner later.
What is removed, and what can be kept?
Porous material that has grown mold is usually removed, such as carpet pad, paper-faced drywall and particle board. Hard surfaces can often be cleaned and kept, and the decision is recorded.
Wood that has a surface growth can sometimes be cleaned and dried, while wood that is soft or has grown into its fibers is removed. Metal, glass and sealed plastic can usually be cleaned and kept.
Bleach is not a substitute for removal of porous material. The owner should not rely on a surface wipe to deal with a material that has grown mold in its body.
What should be done in the house during removal?
The affected room is closed off, the air is kept from the rest of the house where that is practical, and the people who are sensitive to mold are kept out of the work zone.
Removing mold releases spores into the air, so the room is sealed with plastic and kept at a lower air pressure where practical. Dust is wetted rather than swept, and porous material is bagged before it leaves the room.
People with asthma, allergies or a weak immune system should not be in the house during the removal, and anyone who develops symptoms should talk to a doctor. The record should note the date of the removal and the areas it covered.
What is the owner's checklist after mold work?
The readings should be dry, the work should be recorded, the paperwork should be in the file and the room should be rechecked after the work.
Ask for the readings from the recheck and for the record of what was removed and cleaned. Keep any test results, the company's paperwork and the photographs together.
A recheck after a few weeks is the best guard against growth returning under new finish. If a stain or a smell comes back, the readings should be taken again, and the owner should call before the room is closed.
How do readings show that a wall is dry?
A reading is a number on a meter that is compared with the goal for that material. The goal is different for wood, plaster and masonry, and the reading is taken at the same points on every check.
The trend matters as much as any single number. A reading that falls steadily toward the goal shows the material is drying, while a reading that stops falling shows the moisture is still in the material or still coming from somewhere.
A wall is ready to close when its readings have reached the goal on two checks in a row, and the record shows the numbers. An owner who asks for those readings can check the drying for themselves.
What about mold in the air of a whole house?
Mold spores are in the air of every house, and a visible growth in one room is the source to deal with. The general air of the house is not a reason for alarm on its own, and a test of the whole house is rarely the right first step.
The question is whether a source of moisture is still present. Once the source is stopped and the room is dry, the air in the house will generally return to its normal state, and ventilation helps with that.
Where a household has someone with asthma or allergies, the owner should ask a doctor what level of concern is appropriate, and should keep that person away from the work area during any removal.
Which materials are most often left wet?
The materials most often left wet after a loss are the ones hidden behind a finish or under one: the bottom plate of a wall, the subfloor under carpet, the back of a baseboard and the insulation in a closed cavity. Those are the places the readings should check first.
Surfaces that dry quickly are rarely the problem. The problem is the material that dries slowly and is closed up before it is dry, and the readings are the only reliable way to find it.
A household that finds a damp smell after a finished room has been closed should call the line and ask for the readings. The earlier the check, the smaller the opening that is needed to find the moisture.
Frequently asked questions
Is mold after water damage dangerous?
It depends on how much there is and who is exposed. Anyone with asthma, allergies or a weak immune system should be kept away from visible growth and should ask a doctor about any symptoms.
Can I paint over mold?
No. Paint hides growth and does not stop the moisture that feeds it. The material needs to be dried, cleaned or removed first.
Does drying prevent mold?
Drying is the main defense, because it removes the moisture that mold needs. It does not clean up growth that has already started.
Who should take a mold test?
Ask the company who will take the sample, who will analyze it and what paperwork covers that work. The results should be in writing.
Will insurance pay for mold?
Many policies place limits on mold coverage, and the policy and the insurer decide. Keep the photographs, readings and any test results, and read the insurer's written decision.
Do I need a permit for mold removal?
That depends on the work and the local rules. Ask the city or town building department whether a permit applies to the removal or to the repair that follows.
Should I use a fan in the affected room?
Moving air helps drying, but a fan should not be run in a room with growth until the room has been sealed and the work plan says so. Ask the technician how the air is to be moved.
Sources
This guide is general information for Lake County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.