Mold in Indiana: basements, an 87 percent morning, and no license

Indiana's four NOAA stations report 70 to 72 percent annual mean relative humidity with morning means of 81 to 83 percent, and the morning figure climbs to 87 percent in August and September. The calculated annual mean dew point spreads from 40 F at South Bend to 48 F at Evansville, an eight-point gap that follows the state's north-to-south run and is the single most useful line on this table.

The monthly shape is the humid continental signature. Relative humidity peaks in December at 77 percent and January at 76, in the sealed heating months, because cold air reads high while carrying little water. Indoors that means winter moisture is generated inside: showers, cooking, laundry, condensing on cold glass and inside cold wall cavities. Then the pattern flips in late summer, when 87 percent morning air meets basement floors that are still holding spring's cold. Indiana has two different mold seasons with two different fixes, and applying the summer fix in winter makes things worse.

The bulk-water half runs north to south. Northern Indiana takes lake-effect moisture off Lake Michigan and a long heating season. Southern Indiana sits on the Ohio River, and Evansville's 47.9 inches of rain and 48 F dew point are Kentucky numbers rather than Great Lakes ones. Between them the state is full of sump pumps, which is the clearest possible signal about what the housing stock is fighting. EPA guidance treats porous materials wet longer than 24 to 48 hours as at risk of mold growth, and a basement that takes water in a June storm clears that bar before the weekend is over.

Indiana against the national picture

Relative humidity figures are the mean of the morning and afternoon observations NOAA publishes for each first-order station, rounded to whole percent. Dew point is calculated from the NOAA normal mean temperature and that mean relative humidity using the Magnus formula, so treat it as a derived figure rather than a published one.

The eight-point dew point spread is the real story on this table. South Bend at 40 F and Evansville at 48 F are not the same climate, and dew point is the honest measure because it does not move with temperature the way relative humidity does. Evansville's air carries substantially more water year-round, which is why southern Indiana basements need mechanical dehumidification for more months than northern ones do, and why the same construction detail performs differently at the two ends of the state.

What all four share is the morning. Every station reports a morning mean in the low 80s, and the statewide morning figure reaches 87 percent in August and September. That is the number that decides whether a cool basement wall picks up condensation overnight, and it is high everywhere in Indiana. Neighboring reports for Illinois, Ohio, Michigan and Kentucky cover the states this one sits between.

EPA and CDC name the same core genera for humid continental climates. In Indiana housing they concentrate in basements and lower levels through late summer, and at cold winter surfaces the rest of the year.

Species information is general and informational. Health responses vary. See a licensed physician for symptom evaluation. Species sources: EPA Mold Remediation in Schools and Commercial Buildings, EPA A Brief Guide to Mold Moisture and Your Home, CDC National Center for Environmental Health guidance.

No Indiana agency publishes a mold remediation price schedule. The Indiana Department of Health's Indoor Air Quality program states the reason plainly: apart from 410 IAC 33, which covers indoor air quality in schools and state agencies, there are no enforceable indoor air quality laws in Indiana, and the program relies on federal and published guidelines to make recommendations. There is no state standard to price against.

The Indiana cost driver is the finished lower level. Indiana builds them, and a finished basement that takes water is a demolition and rebuild rather than a cleanup: drywall out, studs exposed, carpet and pad gone, cabinetry out. The mold line on that invoice is small and the reconstruction line is large. An unfinished basement with the same water event is a pump, a dehumidifier and time.

The second driver is the sump system, because in Indiana it is usually the thing that failed. If the water came in because the sump quit during a storm or lost power, the honest scope includes a replacement pump, a battery or water-powered backup, and a check of the discharge line, before anyone talks about drywall. Remediating a basement and leaving the same single unbacked pump in place is buying the next event.

The third is that Indiana has no state credential to check at all, so bids differ in scope as much as in price. Get an itemized written scope from each. Indiana law does require home improvement contracts over $150 to be in writing, which the Attorney General's storm-chaser guidance confirms, so insist on the written contract as a matter of law rather than preference. Our national mold remediation cost guide covers what moves a quote in any market, and the cost estimator lets you scope your own job first.

On insurance: sump pump failure and sewer backup are usually separate endorsements rather than standard coverage, and in a sump-pump state that gap is the one that hurts. Surface-water flooding is excluded from a standard homeowners policy entirely. Check both endorsements before storm season and read our guide to homeowners insurance and mold.

Indiana does not license or certify mold assessors or mold remediators, and it goes further than most states: it does not license general contractors or home improvement contractors at state level either. The Indiana Professional Licensing Agency publishes the complete list of the 41 professions it regulates, and mold appears nowhere on it. Contractor licensing in Indiana is a city and county matter, so the answer to whether your contractor is licensed depends entirely on which municipality your house sits in.

The Indiana Department of Health confirms the gap from the health side. Its Indoor Air Quality program states that apart from 410 IAC 33, which covers indoor air quality in schools and state agencies, there are no enforceable indoor air quality laws or regulations in Indiana, and that federal and other published guidelines are used to make recommendations instead. Its mold section carries no state-authored guidance and links out to EPA and CDC.

That leaves two real protections. The first is the written contract requirement: Indiana law requires home improvement contracts over $150 to be in writing, which the Attorney General's storm-chaser guidance sets out. Use it. A written contract that itemizes scope is the document that makes a later complaint actionable. The second is the Attorney General's Consumer Protection Division, which handles contractor fraud and publishes specific post-storm guidance, because storm-chasing crews are a recurring Indiana problem.

For the mold work itself the whole credential check is yours. Call your city or county to find out what local contractor registration applies and confirm the company holds it. Then ask for IICRC certification, ask whether the work will follow ANSI/IICRC S520, ask whether the same firm is doing the assessment and the remediation, and ask for daily moisture readings by material. Verify insurance directly with the carrier rather than accepting a certificate the contractor hands you.

Indiana has no mold-specific statute. A mold complaint runs through Indiana Code 32-31-8-5, which requires a landlord to deliver the rental premises in a safe, clean and habitable condition, to comply with all applicable health and housing codes, to keep common areas clean and proper, and to provide and maintain plumbing sufficient for hot and cold running water, sanitary systems, and heating, ventilating and air conditioning systems in good and safe working condition. Mold is not named, so a tenant argues it as a habitability breach or, usually more effectively, as a failure of the plumbing or HVAC system that produced the moisture.

The enforcement path is Indiana Code 32-31-8-6, and it is strictly conditional. A tenant cannot sue unless four things are true: the tenant first gave the landlord notice of the noncompliance, the tenant gave the landlord a reasonable amount of time to make the repair, the tenant did not block access for that repair, and the landlord then failed or refused to fix it. Miss any one of those and the claim does not get off the ground.

What makes it worth doing properly is the remedy. A prevailing tenant can recover actual and consequential damages, attorney's fees and court costs, injunctive relief, or any other appropriate remedy. Attorney's fees change the economics of a modest claim entirely, because a case that would cost more to bring than it recovers becomes worth bringing.

One timing detail matters. The landlord's liability for damages begins when the landlord has notice or actual knowledge and has either refused to remedy or failed to remedy within a reasonable time, whichever comes first. So the date of your notice is the date the meter starts. Send it in writing even though the statute does not say the notice must be written, date it, describe the condition and the water source specifically, and keep proof of delivery. Our landlord letter generator produces that notice, and our guide to mold and apartment rights covers the general playbook.

General information, not legal advice. For your situation, talk to a Indiana attorney, a legal aid office, or your local tenant council.

A sump-pump state with two mold seasons and no state credential. Three moves cover most of it.

A. Treat the sump system as the most important appliance in the house

In Indiana, the basement failure that produces a remediation job usually starts with a pump that quit at the wrong moment. Test the pump by pouring water into the pit, not by looking at it. Add a battery or water-powered backup, because storms take the power and the pump at the same time. Check the discharge line runs well away from the foundation and does not freeze shut in January. Confirm the check valve works. That package costs a fraction of one remediation and prevents the event rather than cleaning up after it.

B. Own the basement in August and September

The morning mean reaches 87 percent while basement floors are still holding spring's cold, which is the widest gap of the year between air moisture and surface temperature. Opening a basement window on a humid August morning makes the walls wetter, not drier. Run a dehumidifier with a condensate pump and hold the space below 50 percent. Outside, direct downspouts at least six feet from the foundation and grade soil to slope away. Our indoor humidity calculator shows measured relative humidity plus calculated dew point.

C. Flip the strategy in winter

Indiana's relative humidity peaks in December and January, but the mechanism is the opposite one. The air outside carries little water at a 40 to 48 F dew point, and the moisture that matters is what you generate inside a sealed house. Target roughly 30 to 35 percent indoor relative humidity in the cold months rather than 50, run bath and kitchen exhaust fans on a timer, confirm the dryer vents outdoors, and turn a furnace humidifier down in January. Running a dehumidifier against outdoor air in a January basement accomplishes nothing; ventilating and lowering interior moisture does.

Monthly mean relative humidity across Indiana's four NOAA stations. The daily mean peaks in December and the morning mean peaks in August and September, which is why the state effectively has two mold seasons with opposite fixes.

August and September are the basement window. The morning mean reaches 87 percent while below-grade surfaces are still cool. This is when Penicillium takes hold on stored cardboard and carpet padding, and when a finished lower level first smells musty. Run the dehumidifier through this stretch even when the upstairs feels comfortable.

June is the storm and sump window. Heavy summer rain on saturated ground is what overwhelms a sump system, and southern Indiana adds Ohio River exposure on top. Test the pump before June, not after the first storm.

December and January are the indoor-moisture window. The daily mean sits at 76 to 77 percent while the air outside carries little water. In a sealed, heated house every cold surface becomes a condensation target, and window sills and exterior-wall closet corners go first. The fix here is ventilation and a lower indoor target, not a dehumidifier. The mold risk by ZIP tool gives you the local read.

Indiana runs indoor air quality as a schools-and-state-agencies program with public education attached, and routes contractor problems to the Attorney General. These are the starting points.

Every source chip on this page points here. Agency and statute pages first, then the federal technical references.