Ann Arbor, Washtenaw County
Mold remediation in Ann Arbor: the city tells landlords to bleach it. The county says don't.
Both offices are quoting their own real policy, and both are right about the job they do. But if you own property here, the gap between those two answers is where your money goes, because one of them ends the inspection and the other one ends the mold. This site is mostly about telling them apart.
Two offices, one question
The same county, opposite advice
Ann Arbor inspects every rental unit in the city on a 30-month cycle. When an inspector finds mold, the city's own guidance to tenants describes what happens next in unusually plain terms.
If we can physically see the mold, we will contact the owner/agent and require them to bleach and/or use mold killing paint on any surface that will allow.City of Ann Arbor · Rental housing tenant resources
Six miles away, the Washtenaw County Health Department publishes guidance on the same question and reaches the opposite conclusion.
The use of a chemical or biocide that kills organisms like mold (chlorine bleach, for example) is not recommended as a routine practice during mold cleanup… dead mold can still cause allergic reactions in some people. In addition, background mold will continue to grow if moisture is still present.Washtenaw County Health Department · Mold cleanup and removal
Why neither office is wrong
A rental inspector is enforcing habitability under the city's Housing Code, and needs a remedy that an owner can carry out and an inspector can verify by looking at it. Bleach and mold-killing paint satisfy both of those. A health department is answering a different question: what stops this recurring. On that question a biocide does very little, because the mold was a symptom of water and the water is still there.
The practical consequence for a property owner is blunt. Follow only the first answer and the wall passes, the certificate issues, and the same inspector is back in thirty months looking at the same wall. The federal guidance both offices ultimately point at says the same thing the county does: the EPA's own remediation guide states that the use of a biocide, such as chlorine bleach, is not recommended as a routine practice during mold remediation.
So the useful question to put to any contractor here is not what they intend to kill it with. It is where the water is coming from, how they established that, and what stops it.
Who is checking credentials
Michigan does not license mold work. It licenses the repair afterwards.
There is no state mold license in Michigan. No assessor registry, no remediator certificate, nothing a contractor has to hold before working on your basement. What the state does run is EGLE's Clean Air Consultant Directory, which is a list, not an endorsement: EGLE states plainly that it does not recommend or endorse any company on it and that the quality of service is not known or implied by the listing.
The rebuild is different. Under MCL 339.2401(a) the residential builder rules exempt work where labor and materials come to less than $600. Above that line, replacing the drywall, the insulation and the trim is licensed work needing a Residential Builder or a Maintenance & Alteration license from LARA. Which produces the odd situation that nobody is licensed to take the moldy wall out, and the person putting it back needs a license to do so.
Scale sets the method
Ten square feet, and a hundred
Two numbers decide almost everything about how a mold job is run, and they are public. Knowing them is the cheapest way to tell whether a quote is proportionate to the problem in front of you.
- Under about 10 square feet (roughly a three-foot square patch), Washtenaw County's position is that in most cases you can handle it yourself, with gloves, goggles and an N-95, and it publishes the method.
- Between 10 and 100 square feet, the EPA's guide calls for limited containment: a single layer of 6-mil fire-retardant polyethylene sealed to floor and ceiling, so the spores raised by the work stay in the room they came from.
- Above 100 square feet, full containment, with double layers and an airlock at the entry, because at that size the demolition puts enough into the air to matter to the rest of the house.
Two things that override the numbers
Size stops being the deciding factor in two situations, and both are worth knowing before anyone quotes. If the water was sewage or otherwise contaminated, the county's guidance is to bring in someone experienced with contaminated water regardless of how small the patch is. And if the heating and cooling system may be involved, the instruction is to stop running it. A contaminated air handler will distribute the problem through every room it serves faster than any containment can catch up.
Read the other direction, these thresholds are also a check on the person quoting. Full containment and negative air for a patch behind a toilet is not caution, it is a bigger invoice.
What we arrange in Ann Arbor
Five kinds of mold work
Mold inspection and moisture diagnosis
Finding the water before pricing the repair. Washtenaw County’s own position is that in most cases sampling is not necessary, which makes the visual survey the thing you are actually buying.
What this involves → 02Basement and crawl space mold
Where most Ann Arbor mold lives. A below-grade wall can be wet from outside, wet from condensation, or wet from a leak, and the three want completely different repairs.
What this involves → 03Attic mold and roof ventilation
Usually a ventilation fault rather than a roof leak. A bath fan discharging into the attic puts warm wet air against a cold roof deck every night of a Michigan winter.
What this involves → 04Water damage drying and material removal
The 48-hour window the EPA sets for drying wet building materials, and which porous materials have to come out rather than be dried in place.
What this involves → 05Rental property mold and certificates of compliance
Ann Arbor inspects every rental unit every 30 months. Passing that inspection and fixing the moisture behind it are two different jobs, and only one of them holds until the next one.
What this involves →Straight answers
What Ann Arbor property owners ask
Should I get the mold tested first?
Usually not, and the county says so directly: in most cases testing or sampling for mold is not necessary, because there are no established safe levels or regulatory standards to compare a result against. Ann Arbor's own rental office goes further and says it cannot test nor recommend anyone to test.
Testing earns its cost in a few specific situations: somebody in the household has symptoms, there is a musty smell with nothing visible, you suspect hidden growth after a leak, you need to confirm a remediation worked, or you need documentation for a sale or a dispute. Outside those, the money is better spent finding the water.
Is black mold different from the other kinds?
Not in a way that changes what you do about it. Mold that looks black is not automatically Stachybotrys, and identifying the species does not change the remediation: the material comes out, the moisture gets fixed, and the same protective equipment is worn either way. This is one of the reasons public health guidance is so consistently unenthusiastic about testing. The county's summary of the whole subject is one sentence: if you can see it or smell it, fix it.
What has to be thrown away, and what can be cleaned?
The dividing line is whether the material is porous. Washtenaw County lists carpet and pad, ceiling tiles, drywall, insulation, paper products, plaster and wood products other than solid wood as things that need removing once they are wet and growing mold. Non-porous surfaces (plastic, glass, metal, solid wood) can usually be saved by scrubbing with hot water and a non-ammonia detergent, then rinsing and drying. A contractor who proposes to clean and seal moldy drywall in place is proposing something the county's own guidance does not support.
How fast do I have to act after water gets in?
The number to work to is 48 hours. The EPA's remediation guide asks whether building materials have been wet more than 48 hours and instructs that non-moldy items be dried within that window. Inside it you are drying a wet house; outside it you are increasingly likely to be removing material instead. That is why the first call after a burst pipe or a basement flood is worth making the same day rather than after the weekend.
My basement is damp every summer. Is that mold?
It is the condition mold needs. The target is a relative humidity between 30% and 60%, and a Michigan basement in July sits above that easily, because warm humid air meeting cool below-grade walls condenses on them. That is a different problem from water coming through the wall, and it wants a different fix: dehumidification and ventilation instead of excavation. Telling the two apart from inside the basement is most of what a survey is for.
Who actually turns up?
A local remediation company. This site takes your details and passes them to the company covering Ann Arbor, who will contact you to arrange the visit. We are not the crew and we do not price the work.
Start with the water
Tell us what you're seeing
The first useful step is a survey that establishes where the moisture comes from, not a price for removing what you can already see. A quote written before anyone has found the source is a quote for doing this again.
Rough details are enough to begin with: which part of the building, roughly how big an area, and whether there was a leak or a flood you know about. Photographs help more than people expect, and so does knowing whether it is worse in winter or in summer.