Mold testing: when you need it and when you don't
Most mold questions start with a smell or a stain. Here is what EPA says about testing, cleaning up yourself, and when a professional makes sense.
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Do you need a mold test?
Usually not. EPA says that when mold is visible, sampling is usually unnecessary, and there are no federal limits to compare results against. Fix the moisture source first, clean small areas (under about 10 square feet) yourself, and call a professional for larger growth, heavy water damage or a musty smell you can't trace.
Where should you start with mold?
Mold needs moisture to grow. EPA puts it simply: "The key to mold control is moisture control." Find and fix the water source first, whether it's a roof leak, a plumbing drip, condensation or a damp crawl space.[EPA]
Warning signs
- A musty or earthy smell that won't go away
- Visible spots or fuzzy growth on walls, ceilings, wood or fabric
- Water stains, peeling paint or warped materials
- Condensation on windows, walls or pipes
Do you actually need a mold test?
Testing still has its uses. EPA notes that surface sampling may be useful to check whether an area was properly cleaned after remediation, and that sampling should be done by professionals who know how to interpret it.[EPA] A professional inspection, with moisture readings and a look into hidden spaces, can also track down where the water is coming from.
Can you clean it yourself?
If the moldy area is less than about 10 square feet (roughly a 3 ft × 3 ft patch), EPA says you can usually handle it yourself. With heavy water damage or larger growth, EPA points to professional guidance.[EPA]
- Wear an N-95 respirator, gloves and goggles.
- Scrub mold off hard surfaces with detergent and water, then dry completely.
- Absorbent materials like ceiling tiles or carpet may need to be thrown away if moldy.
- Don't paint or caulk over moldy surfaces.
Source: EPA A Brief Guide to Mold, Moisture and Your Home
Who should be careful around mold?
Molds can produce allergens and irritants. Sensitive people may get hay-fever-type symptoms, and mold can trigger asthma attacks in people with asthma.[EPA] CDC has more on who is most at risk.[CDC] If you have health concerns, talk to a doctor.
How do you keep mold from coming back?
- Dry water-damaged areas and items within 24–48 hours.
- Keep indoor humidity below 60%, ideally 30–50%. A $10–$50 humidity meter tells you where you stand.
- Vent bathrooms, dryers and other moisture sources to the outside; keep A/C drip pans clean and drain lines flowing.
Source: EPA A Brief Guide to Mold, Moisture and Your Home
What does mold work cost?
Typical national ranges: mold inspection $303–$1,075; air or surface samples $250–$500; remediation $1,223–$3,757, with HVAC and whole-house jobs far higher. Details in the cost guide.