Homeowner guide

Do I need a professional for mold?

Last reviewed November 2026. The agency pages linked in this guide were checked November 5, 2026. Dates are Mountain Standard Time (Phoenix).

Browse mold remediation contractors with a license on record

Sometimes you do, and sometimes EPA says you can handle it yourself. The dividing line EPA publishes is the size of the moldy area: less than about 10 square feet, which it describes as less than roughly a 3 ft by 3 ft patch. In most cases, EPA says you can do that job yourself. If there has been a lot of water damage, or mold covers more than 10 square feet, EPA points you to its remediation guide instead (EPA: Mold Cleanup in Your Home).

Size is not the only test. Even a small area can be the wrong job to do yourself if the heating and air-conditioning system may be involved, the water was sewage or otherwise contaminated, or you have health concerns. Those exceptions are on the same EPA page.

EPA's size line

In most cases, you can do it

Less than about 10 square feet (roughly a 3 ft by 3 ft patch) (EPA: Mold Cleanup in Your Home)

EPA points to its remediation guide

A lot of water damage, or mold growth covering more than 10 square feet. The guide is written for schools and commercial buildings, and EPA says it applies to other buildings too (EPA: Mold Cleanup in Your Home).

What to do next

When EPA says to get help

All of these are from EPA's cleanup page (EPA: Mold Cleanup in Your Home).

  • More than about 10 square feet of mold, or a lot of water damage. Consult Mold Remediation in Schools and Commercial Buildings. EPA says that document applies to other building types even though the title is about schools and commercial buildings.
  • If you hire someone, EPA says to make sure the contractor has experience cleaning up mold, to check references, and to ask them to follow that remediation guide, ACGIH or IICRC guidelines, or other professional or government guidelines.
  • If you suspect the HVAC system may be contaminated (it is part of a moisture problem, or there is mold near the intake), do not run the system. EPA says running it could spread mold through the building. Read EPA: Should You Have the Air Ducts in Your Home Cleaned? before you go further. For that situation, start with the mold remediation directory and ask about HVAC experience.
  • If the water or the mold damage was caused by sewage or other contaminated water, EPA says to call a professional who has experience cleaning and fixing buildings damaged by contaminated water.
  • If you have health concerns, EPA says to consult a health professional before you start cleanup.

If the area is small enough to do yourself

EPA's tips for a small job are on the cleanup page. CDC's cleanup notes are separate and are quoted on their own (EPA: Mold Cleanup in Your Home).

  • Fix plumbing leaks and other water problems as soon as possible. Dry everything completely.
  • Scrub mold off hard surfaces with detergent and water, and dry completely. Do not paint or caulk moldy surfaces. EPA says paint over mold is likely to peel.
  • Absorbent or porous materials, such as ceiling tiles and carpet, may have to be thrown away if they are moldy. EPA says mold can fill the spaces in porous materials and may be impossible to remove completely.
  • CDC says if you see or smell mold you should remove it, and that you do not need to know the type. CDC says mold can be removed from hard surfaces with household products, soap and water, or a bleach solution of no more than 1 cup of household laundry bleach in 1 gallon of water. Never mix bleach with ammonia or other cleaners. Open windows and doors, and wear rubber boots, rubber gloves, and goggles if you use bleach (CDC: Mold).
  • CDC says to keep indoor humidity no higher than 50% all day. EPA's brief guide says, if possible, keep indoor humidity below 60 percent, ideally between 30 and 50 percent (EPA: A Brief Guide to Mold, Moisture and Your Home). The two pages do not use the same ceiling. Both are quoted here.

Do you need a mold test first?

Usually not, if you can see the mold. EPA says that when visible mold is present, sampling is unnecessary in most cases. No EPA or other federal limits have been set for mold or mold spores, so a sample cannot show whether a building meets a federal mold standard. Surface sampling may help show whether an area was cleaned. EPA says sampling should be done by professionals who have specific experience designing the sampling and interpreting the results (EPA: A Brief Guide to Mold, Moisture and Your Home).

CDC does not recommend mold testing. It says the health effects differ from person to person, so a culture cannot tell you whether someone will get sick, and that there are no set standards for an acceptable amount of mold in a home. CDC says the useful step is to remove the mold and stop it from growing again (CDC: Mold).

CDC also says exposure to damp and moldy places may cause a variety of health effects, or none at all. For some people it describes a stuffy nose, sore throat, coughing or wheezing, burning eyes, or skin rash, and more serious reactions for people with asthma, mold allergy, weakened immune systems, or chronic lung disease. Those are CDC's statements. If you are sick, talk to a doctor. This guide cannot tell you whether mold caused a symptom.

What a larger job costs

The mold remediation cost guide puts a small job of about 100 square feet at about $1,500 to $3,200. That figure is the guide's arithmetic on a public Michigan contract for institutional buildings, plus a mobilization fee (State of Michigan statewide contract 071B7700154). It is not a residential quote and not a price for your home. No government agency publishes a residential average on that page. For a job above the 10 square foot line, or for HVAC or sewage damage, use the directory and request a quote from a profile.

FAQ

Can I clean mold myself?

EPA says in most cases yes, if the moldy area is less than about 10 square feet (roughly a 3 ft by 3 ft patch), you follow its cleanup tips, and the exceptions below do not apply (EPA: Mold Cleanup in Your Home).

What if the area is larger than 10 square feet?

EPA says to consult its mold remediation guide for schools and commercial buildings, which it also applies to other buildings. If you hire someone, check that they have mold-cleanup experience and references (EPA: Mold Cleanup in Your Home). The state list is the mold remediation directory.

Do I need a mold test?

CDC does not recommend mold testing (CDC: Mold). EPA says sampling is usually unnecessary when mold is visible, because there is no federal limit to compare a sample against (EPA: A Brief Guide to Mold, Moisture and Your Home).

What if the mold is in the HVAC system?

Do not run the system. EPA says that could spread mold through the building, and it points you to its air-duct guide (EPA: Should You Have the Air Ducts in Your Home Cleaned?). Use the directory for a contractor who has done this work.

Will the mold come back?

EPA and CDC both say the moisture problem has to be fixed, or mold can grow again. CDC says to clean up and dry out within 24–48 hours after a flood, and to fix roof, wall, and plumbing leaks (CDC: Mold).

Sources

The $1,500 to $3,200 figure is the small-job example already published on the mold cost guide. It is not a new range.

Contractors by state

These links go only to states where the directory currently lists mold remediation contractors.

This guide is general information from public sources such as EPA, CDC and HUD. It is not medical, legal or professional advice. Rules differ by state and city; check with your state health or environmental agency before starting work. If you have health concerns, talk to a doctor. Contractors listed on remediationpros show 'License on record' from official rosters; confirm current status with the issuing agency before hiring.