Mold Removal St. Louis: $1,223 to $3,757 + City Rental Law

We found no St. Louis-only mold removal price, so every row is a national figure.

Do this now: mold in a St. Louis home

1. Find and stop the water first. A leak, a backup or a wet basement will bring mold back after any cleanup.
2. If it covers less than about 10 square feet, EPA says a homeowner can generally handle the cleanup. Bigger areas, or a lot of water damage, call for a professional.
3. Do not run the furnace or AC if you think the ducts are moldy, EPA says.
4. Never mix bleach with ammonia or other cleaners, the CDC warns.
5. Renting? Tell the owner in writing. St. Louis Ordinance 71946 requires owners to prevent and remediate mold in rental units.
6. If a claim is possible, photograph it before cleanup and call your insurer. Do not sign a contract that hands your claim to a contractor.

Is it urgent? When St. Louis mold needs a pro now

Mold is urgent when it covers more than about 10 square feet, follows sewage or flood water, sits in the ductwork, or someone in the house has asthma or a weak immune system. The CDC says people with asthma or mold allergies may have severe reactions and immune-compromised people can get lung infections. A small spot on a bathroom ceiling can wait for a scheduled visit. If the mold came from a leak or backup that is still wet, call for drying first; EPA says to dry materials within 24 to 48 hours. See water damage restoration in St. Louis.

St. Louis's rental mold law: Ordinance 71946

St. Louis Ordinance 71946, "Prevent and Remediate Mold," approved Dec 30, 2024, puts mold on the owner in rental housing. It requires owners to prevent and remediate mold in rental dwelling units, bars a rental unit from getting a Certificate of Inspection while mold is present, and requires owners to notify tenants of units where mold is found. That makes mold removal part of getting a St. Louis rental through inspection, not an optional cleanup.

To ask the City to look, request an interior residential property inspection through the Citizens Service Bureau online form or at 314-622-4800. The City says fees may apply for some inspections.

Where St. Louis mold comes from

Mold follows water: EPA says wet materials dried within 24 to 48 hours usually do not grow mold, so the leak, backup or damp basement behind it is the real job. MSD says the whole sewer lateral is private property, so a backup from a cracked or root-filled lateral is the owner's to fix; MSD takes backup calls at 314-768-6260. The housing stock is old: the Census Bureau's 2020 to 2024 survey puts the median year built at 1939 or earlier, with 57.9% of units built in 1939 or earlier. EPA lists hidden mold spots including the back of drywall, inside walls around pipes and inside ductwork. Fix the source with a St. Louis plumber before the remediation crew closes anything up.

Do you need mold testing?

Usually not when you can see it. EPA says sampling is usually unnecessary when visible mold is present and that no federal limits exist for mold or spores, and the CDC does not recommend mold testing. Testing helps when you smell mold but cannot find it, or to show a cleanup worked; HomeAdvisor puts basic testing at $250 to $350. More on mold inspection.

Local rules, programs and climate for St. Louis, from the official city, utility, state, Census and NOAA pages listed under Sources.

Questions to ask a St. Louis mold removal company

1. What caused the mold, and who will fix the source?
2. How many square feet will you remove, and will you contain the area while you work?
3. Will you follow recognized remediation guidelines, as EPA advises? Ask for references from past mold jobs.
4. If this is a rental, will your paperwork help the unit pass the City's inspection?
5. Can I see proof of insurance and a written price before work starts?

More St. Louis guides

Leaks and sewer laterals: plumber in St. Louis. Flooded basement: water damage restoration in St. Louis. Damp ducts or a furnace drain: HVAC repair in St. Louis. Compare mold removal in Kansas City and mold removal in Indianapolis, or read the national mold remediation guide. Calls go to an independent company that serves your area and takes this kind of job (how calls work).