The short answer
- Fix the water first. If you clean up mold but don’t fix the moisture problem, the mold will most likely come back [1].
- Size up the job. EPA says you can usually handle an area smaller than about 10 square feet yourself. Get experienced professional help for larger areas, lots of water damage, sewage or contaminated water, or a suspected contaminated heating and cooling system [1, 2].
- Protect the most sensitive people. If you have health concerns, talk to a health professional before cleanup starts. EPA advises a more cautious approach when people with severe allergies or asthma are present [1, 3].
- Remove mold; don’t just kill it. Dead mold can still cause allergic reactions, and routine bleach use isn’t recommended [1, 3].
Finding mold in your home is stressful, and if you or someone you love is already unwell, it can feel like an emergency. It’s usually not one. Mold problems are solved by careful, methodical steps, and rushing (tearing out drywall with no protection, or bleaching and painting over a stain) can make things worse.
This guide follows EPA’s published guidance and adds notes for households where someone is sensitive to mold. Our remediation decision tree is a printable companion, and our Mold Toxicity page covers the health side.
Step 1: Protect people before you touch anything
- Talk to a health professional first if you have health concerns. EPA says this directly [1, 2].
- Keep sensitive people out of the work area. EPA’s guidance calls for a more cautious approach when sensitive individuals, such as people with severe allergies or asthma, are present [3]. If you’re the one who’s sick, consider asking someone else to do the work.
- Consider staying elsewhere for big jobs. For large areas of contamination, EPA’s remediation guide says plans may include temporarily relocating occupants [3].
- Don’t run the heating and cooling system if you know or suspect it’s contaminated, because it could spread mold through the building [1].
Step 2: Find and fix the water
EPA puts it plainly: “the key to mold control is moisture control” [1]. Look for:
- Roof, window and plumbing leaks
- Condensation on windows, walls or cold pipes, which can be a sign of high humidity
- Water collecting around the foundation, or gutters that send water toward the house
- Air conditioning drip pans and drain lines that are dirty or blocked
Mold can also hide behind drywall, wallpaper or paneling, under carpet and pads, above ceiling tiles and inside ductwork. A musty smell with no visible source, or known water damage plus health complaints, are reasons to suspect hidden mold [1]. Be careful investigating: peeling back wallpaper over mold, for example, can release a large amount of spores [1]. If you suspect hidden mold, EPA suggests considering an experienced professional [1].
If you rent, report leaks and moisture problems to your landlord or building manager right away. If they aren’t fixed, you may be able to contact local or state health or housing authorities [1].
Step 3: Size up the job
- Less than about 10 square feet (roughly a 3-by-3-foot patch): in most cases you can handle it yourself, following EPA’s cleanup tips.
- More than 10 square feet, or a lot of water damage: follow EPA’s more detailed remediation guide, which applies to homes as well as schools and offices.
- Sewage or other contaminated water: call a professional with experience in contaminated-water damage.
- Suspected heating and cooling contamination: read EPA’s guidance on air duct cleaning before doing anything.
In a sensitive household you may prefer professional help even for a smaller job. That’s a reasonable call: EPA notes that professional judgment should guide decisions and its size categories aren’t based on health effects [3].
Step 4: Hire carefully
If you hire a contractor, EPA suggests making sure they have experience cleaning up mold, checking references, and asking them to follow EPA’s remediation guidance, the guidelines of the American Conference of Governmental Industrial Hygienists (ACGIH), the Institute of Inspection, Cleaning and Restoration Certification (IICRC), or other professional or government guidelines [2].
The IICRC’s S520 standard describes procedures for professional mold remediation, including remediator qualifications, safety, containment, structural, heating and cooling and contents remediation, and checking the work afterward [4].
Before work starts, ask for a written plan that explains:
- Where the moisture came from and how it will be fixed
- What will be cleaned and what will be removed
- How the work area will be contained and protected
- How they’ll show you the job is finished
A good plan also changes if hidden mold turns up partway through, which EPA’s guide expects [3].
Step 5: Contain the area and wear protection
Containment keeps mold and dust from spreading to the rest of the house. For larger jobs, EPA describes plastic sheeting around the work area kept under negative pressure, with air exhausted outdoors. If the containment is working, the sheeting should billow inward [3]. Moldy materials should be bagged before they leave the contained area [3].
For small do-it-yourself jobs, EPA suggests [1]:
- An N-95 respirator that fits properly
- Long gloves that reach the middle of the forearm
- Goggles without ventilation holes
Bigger jobs call for more protection, and some respirators require training, medical clearance and fit testing [3].
Step 6: Clean what you can, remove what you can’t
- Hard surfaces: scrub mold off with detergent and water, then dry completely [1].
- Porous materials such as ceiling tiles and carpet may have to be thrown away if they become moldy, because mold can grow into the spaces and crevices and be hard or impossible to remove completely [1].
- Don’t paint or caulk over mold. Clean and dry the surface first; paint over mold is likely to peel [1].
- Skip routine bleach. EPA doesn’t recommend biocides like chlorine bleach as a routine practice, though professionals may use them in some situations. It’s not enough to kill mold; it has to be removed, because dead mold can still cause allergic reactions [1, 3].
- Never mix bleach with ammonia or cleaners that contain it. The fumes are toxic [1].
- Valuable or sentimental items: EPA suggests consulting a restoration specialist [1].
- Dry everything quickly. Drying water-damaged areas and items within 24–48 hours helps prevent new growth [1].
Step 7: Final cleanup
EPA recommends HEPA vacuums for final cleanup once materials have been dried and contaminated materials removed, including dust that has settled outside the work area. The filter must be seated properly, and the filter and contents bagged and sealed when changed [3].
Step 8: Check that the job is really done
EPA’s checklist for a finished cleanup [1]:
- The water or moisture problem has been completely fixed.
- No visible mold or moldy odors remain (staining may still be visible).
- A revisit shortly after shows no new water damage or mold growth.
- People can occupy the area again without health complaints or physical symptoms.
EPA admits that “ultimately, this is a judgment call” [1]. In the CIRS community, many practitioners suggest re-testing with ERMI or HERTSMI-2 after cleanup [5]. EPA calls ERMI a research tool that isn’t validated for routine use, and the CDC doesn’t recommend routine mold sampling [6, 7]. Our ERMI post explains how to read those tests.
Step 9: Keep it from coming back
- Keep indoor humidity below 60%, ideally 30–50%, and check it with an inexpensive humidity meter [1].
- Use bathroom and kitchen exhaust fans, and vent clothes dryers outside [1, 7].
- Clean gutters, make sure the ground slopes away from the foundation, and keep air conditioning drip pans clean [1].
- Act quickly on any new leak or spill [1].
Plan for cost and stress
Remediation can be expensive. A 2024 review of CIRS treatment notes that removing exposure, whether by remediation or moving, can cost tens of thousands of dollars or more [8]. Get more than one quote, ask what insurance might cover, and remember that a good contractor explains their plan rather than pressuring you.
What’s known and what’s debated
Generally accepted: fix moisture, remove mold rather than just killing it, protect workers and occupants, and match the approach to the size of the problem [1, 3, 9].
Debated: how clean a home must be for someone with mold-related illness, and whether dust tests can answer that question. CIRS practitioners use HERTSMI-2 and ERMI cut-offs [5, 10]; EPA says ERMI isn’t validated for that purpose [6].
Questions to ask
A remediation contractor: What’s causing the moisture, and who will fix it? What will you remove versus clean? How will you contain the area? Which guidelines do you follow? How will we confirm the job is done?
Your doctor: Is it safe for me to be home during the work? Should I stay elsewhere? Are there symptoms that mean I should leave the house or seek care?
When to get urgent help
Call 911 or your local emergency number for severe shortness of breath at rest, bluish lips or face, severe chest pain, or drowsiness or confusion with breathing trouble [11]. Signs of a severe allergic reaction, such as throat or face swelling or fainting, also need emergency care; use epinephrine if your clinician has prescribed it [12].
The bottom line
Safe remediation is less about dramatic cleanup and more about doing the basics in the right order: protect people, fix the water, contain the work, remove what’s moldy and check the result honestly. If you’re sensitive, give yourself permission to step back and let others do the physical work. For more on testing, read our ERMI post; for the health side, see our CIRS page.
Sources
Numbers in brackets in the text link to these sources. Links were checked in October 2026. Some sources are written by people who support a particular approach; we've tried to say so in the text.
- U.S. Environmental Protection Agency (EPA). A Brief Guide to Mold, Moisture and Your Home. Web page, accessed October 10, 2026. https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home
- U.S. EPA. Mold Cleanup in Your Home (last updated June 4, 2026). https://www.epa.gov/mold/mold-cleanup-your-home
- U.S. EPA. Mold Remediation in Schools and Commercial Buildings Guide: Chapter 3 (based on EPA 402-K-01-001, reprinted September 2008). https://www.epa.gov/mold/mold-remediation-schools-and-commercial-buildings-guide-chapter-3
- Institute of Inspection, Cleaning and Restoration Certification (IICRC). ANSI/IICRC S520 Standard for Professional Mold Remediation (fourth edition, 2024; web page). https://iicrc.org/s520/
- Surviving Mold (Shoemaker RC). HERTSMI-2 Scoring System (web page). Web page, accessed October 10, 2026. https://www.survivingmold.com/resources-for-patients/diagnosis/hertsmi-2
- U.S. EPA. The Environmental Relative Moldiness Index (ERMI) fact sheet. September 2021. https://www.epa.gov/system/files/documents/2021-09/updated-fact-sheet.ermi-_9.9.21.final_new-template_508-compliant_0.pdf
- Centers for Disease Control and Prevention (CDC), National Center for Environmental Health. Mold (About mold). Reviewed Sept 26, 2024. https://www.cdc.gov/mold-health/about/index.html
- Dooley M, Vukelic A, Jim L. Chronic inflammatory response syndrome: a review of the evidence of clinical efficacy of treatment. Ann Med Surg (Lond). 2024;86(12):7248-7254. PMID: 39649915. https://pmc.ncbi.nlm.nih.gov/articles/PMC11623837/
- World Health Organization (WHO) Regional Office for Europe. WHO Guidelines for Indoor Air Quality: Dampness and Mould. 2009. PMID: 23785740. https://www.ncbi.nlm.nih.gov/books/NBK143941/
- Ou D. Steps of the Shoemaker Protocol (2014; hosted by Surviving Mold). https://www.survivingmold.com/STEPS_OF_THE_SHOEMAKER_PROTOCOL_3.PDF
- MedlinePlus. Asthma. Web page, accessed October 10, 2026. https://medlineplus.gov/ency/article/000141.htm
- MedlinePlus (U.S. National Library of Medicine). Anaphylaxis. Web page, accessed October 10, 2026. https://medlineplus.gov/ency/article/000844.htm