Using a borescope to check a wall cavity for visible moldQ&A on When to Hire a Mold or IAQ Expert

  • MOLD ENVIRONMENTAL EXPERT HIRE FAQs - CONTENTS: Q&A on when to hire a mold or IAQ expert & how to identify an indoor air quality, mold, or odor emergency & what to do in an IAQ emergency
  • POST a QUESTION or READ FAQs about how to decide if a mold, odor or other indoor air emergency exists, what to do in an emergency, and how to determine if professional mold inspection & testing are needed
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FAQs discuss when to hire an expert to inspect & test a building for environmental, health, safety, mold, IAQ hazards:

Here we answer commonly-asked questions about when, how, & why to hire a mold inspector, mold test consultant, or other indoor air quality or environmental expert.

This article series describes how to determine that you should hire an expert for on-site mold or other indoor contamination inspection and testing.

Green links show where you are. © Copyright 2017, All Rights Reserved.

How to Decide When to Hire an Environmental or Mold Inspection / Test Professional

Photograph of fungal fruiting bodies growing out of indoor baseboard trim - a very wet home.

These Questions & Answers, posted originally at MOLD / ENVIRONMENTAL EXPERT, HIRE ? help you to decide how and when mold testing or other indoor air quality investigation and tests are appropriate. If you haven't seen the original article you might want to check it out.

On 2017-06-04 by (mod) re: I have mold infection in my lungs and COPD, what should I DO?


First focus is to get advice from your doctor. If you haven't already done so it's possible that your doctor is going to recommend that you consult with a physician who is a specialist in mold related illnesses and their treatment.

Second it's appropriate to have an expert inspect the places where you spend the most Time - most likely you are home, possibly where you work - to be sure that there is no mold Reservoir that needs to be removed.

For that purpose, it would be a serious mistake to Simply rely on a mold test. There is the risk that the test gives a false negative that is failed to detect something that needs attention.

On 2017-06-03 by Christina Ruiz

I've been found to have mold in my lungs, being asthmatic & having COPD, this has made me very sick. After X-rays, a Ct scan & a probe down my throat into my lungs, all came back for mold. I spent 3 days in the hospital & now have ABPA....what do I do??

On 2017-05-16 by Nick

Contact by phone

On 2017-05-10 by (mod) re: vacant house has bad smell coming from ducts

Please use the search box just above to fo ng our diagnostic article o DIAGNOSE HVAC DUCT ODORS

On 2017-05-1 by Jose

Just moved in to my mothers house. It has been vacant for a few months. Also hasn't had central air. There is a very bad smell coming out of the ducts. Just wanted some advice.

On 2017-04-29 by (mod) re: It smells moldy, when should I be concerned?


If you smell mold there's mold nearby, that's pretty reliable. I have found that tests (like trying to vacuum particles out of a wall cavity through a small opening, or like MVOC testing) are not reliable, sometimes indicating trouble where it's not or indicating no trouble where it is present.

If sunlight, ventilation, heat don't eliminate the complaint then it might be worth a look into the wall cavity at the most-suspect location, a spot determined by a careful inspection for leaks and perhaps aided by a moisture meter (keep in mind that as conditions change a moldy area can dry out so won't show up even though it's still a mold problem). At such a spot I prefer to cut a 4x6 opening to examine the cavity side of drywall, insulation, sides of wood studs, and interior surface of exterior wall sheathing; we're looking for mold or for water stains. A borescope sometimes is enough but much more difficult to use successfully.

If the most-suspect spot is close to the floor we pull off floor molding trim to look behind it and to make our test cut below the trim top - making repairs easier.

On 2017-04-29 18:25:28.419262 by Jan

Our windows face east and have no overhang to speak of. I've been noticing a mildew/mold odor especially when there is dampness in the air. \

My husband has looked at the windows and did not notice anything that would leak. How would we go about testing for mold behind the dry wall with the least amount of damage? When should we be concerned?

On 2016-01-26 09:01:36.240432 by Jennifer

I live In SC and I am a single mom to a 6 and 15 year old and have a dog. I was doing pretty well until moved into this townhome on Nov. 5th and slow started with dog with pink itchy rash figured dust since some stuff in storage than ,

me and my daughter have asthma so fast forward it's insane I have been in and out of the hospital for vitamin deficiances, depression, pnemunia, coughing, dry issues, inomina, mood swings, swollen tongues etc.. so yesterday I said screw this and not a lot but near corners by wall lifted carpets, some tiles, dug by doors and guess what infested with mold of every color possible

and this white chalky stuff everywhere that I have told realtor since moved in is embedded in carpets and broke two new vaccums since day 1 but played dumb..I even moved loose chaulk by daughters tub because had green ring on outside and deep in there oooh boy that's by baby and she has asthma!

I have not slept in nights because not sure if this has messed up my brain or actual invisible mites crawling on my skin too but we all have rashes and I just looked in dogs ears which is knew today and I am freakin something furry in there wtf is in this house and have no where to go but believe we are really sick and I am about to loose my job because too sick to get up or focus or breath. Please help, landlord said mold test report comes back in two day and go from there ..what!

On 2016-01-13 by Patrice

I'm renting an apartment. We moved there in May of 2015 and I became sick in June and have been sick ever since then. It started with headaches then bad indigestion, acid reflux, gastritis, food allergies, itchy skin, hair loss, blurry vision sometimes, brain fog, confusion, shortness of breath, weakness, joint pain, anxiety, depression. Doctors can't seem to tell me what's wrong. All they do is try to treat the symptoms. I've never experienced nothing like this till I move here. I have notice a musty smell in the kitchen that happens when we use the dishwasher

. In the bathroom when we first moved in I noticed on the walls there was places where it looked as though something was painted over. Now whatever it is is starting to come to surface. The toilet is leeking and the sink cabinet wood looks puffed up at the bottom like there is water damage. We have central air and near the air conditioning vent there are water stains that were there when we first moved in. All of the air vent are dirty with dust and have been since we moved in. I'm really concerned that we might have a mold problem.

Where do I begin to take care of this or find out if this is mold. I contacted the LL about it and they sent out someone to take a look and fix the toilet. He denied that what look like mold painted over to me was just a repair they painted over. He call himself fixing the toilet leek but it's leeking again. What do I do?

On 2015-10-08 by Michele S.

Im renting a house and the gutters were run underground. When it rains hard the water backs up and filled the very large light fixture but did not overflow onto the bedroom carpet. The gutter is now running water away from the house and no longer underground so it no longer comes into the light fixture

Also, the owners said they ran a humidifier in there for their son so there is evidence of water marks down the wall that they said they cleaned up yet still, that room smells very musty and the carpet feels damp. The carpet seems to be turning grey after they had it steam cleaned. This is in Seattle. Management company suggests a petri dish from Home Depot. We want to look in the attic and the crawl space along with pulling back the carpet. In another room that was converted from a garage space to a living room, the musty smell is very strong at times.

Outside on the other side of the wall the water pools and goes down between the edge of the driveway and the concrete wall of the house. I use a broom to move the water away and am catching rain in buckets out on the covered patio. Outside smells awful moldy after it rains. I have been having headaches everyday and am experiencing strong muscle twitches in my limbs. My husband is away on travel for his job alot so we are slow in addressing this problem. Should I move out of this house? Thank you for your advice.

On 2015-09-15 by (mod) re: aspergillosis and Aspergillus related illnesses

Caroline and other readers concerned about Aspergillosis and Aspergillus-related illnesses and related tests for mold contamination in the environment, see

On 2015-09-15 by (mod) re: father tested positive for Aspergillis fumigatus


You can find my email at the page bottom CONTACT link and by email I can offer a number for pro-bono consulting in this matter.

There is a place for air testing and properly done it can be informative. But considering the orders of magnitude variation in measurements of the level of airborne particles just in response to very small changes (waving a notebook in the air for example), a "negative" air test result cannot be trusted, and even a "positive" air test for mold that produces a high mold count cannot for a moment be presumed to actually describe the level of exposure of the building occupants to mold.

And no “test for mold” alone is going to tell us where the problem is nor what needs to be done about it. It’s instead a profitable “indicator test” that might find evidence of a problem that’s really there - or it might miss a real problem. The physician needs to be included in the process.

More follows

On 2015-09-15 by Caroline

My father tested positive for aspergillis fumigatus. I called some mold testing people to come out & all of them said they would do an air test in his room ( which is in the basement) and in the basement. I read how you said an air quality test is not always accurate because of the changes in the room, so I was wondering what kind of testing you would recommend. Also, I do have a compost heap outside. So I wondered if I got rid of it, would it take care of the situation?

On 2015-03-11 by (mod) re: basic steps at tracking down mold when it's not visible

I'd study the building for leak history, moisture traps, mold-friendly materials, and make a few small test cuts in the most-suspect areas of ceilings or walls.

On 2015-03-10 by Scott

We have noticed a slight moldy smell in our entryway near our front door. That area has a very high cathedral ceiling that spans around 20 feet into the kitchen and dining areas. The smell is only noticeable in the warmer months/weather. For example, during the winter months, we don't smell it. I have had my house inspected by two different mold companies, who are both reputable.

Neither company could find any issues and were very puzzled. As precaution, I did some crawl space improvements and got new vapor barrier, sealed it, and installed a de-humidifier.

So far no improvement. I have inspected the attic, taken off door trim pieces etc. and have found no mold or moisture. I am concerned there is a hidden problem but I don't know what to do next. I haven't done an mold air test, but have considered it. Any suggestions?

On 2014-03-15 by (mod) re: what does my mold count mean?

Gale, near the top of this article if you click on the bold link titled "Click to Show or Hide Related Topcs"

you'll see a 2-column list of related articles - there click on


for some help understanding airborne mold counts.

keep in mind that "dangerous" depends on where the test was made and what it represents. If the people you hired to "test" your building for mold are not answering your question I'd start by asking for my money back. Just "testing" air for mold, by itself, is not very helpful.

On 2014-03-15 by Gale

Would you please tell me if a Pen/Asp mole count of 9800 is dangerous, and how to handle the situation. Thank you.

Question: Moldy Rental Apartment in a Basement - allergy flare-up

My husband, 5-month old son, and I recently moved into a water-front basement apartment (about two weeks ago) and immediately noticed our allergies flair up. My husband and I are both allergic to mold, but we can't find more than small amounts on the floor boards. In the closet of our bedroom, there is a boarded up septic pump that smells terrible and might be contributing to our problem. Our landlord is not terribly concerned at the moment. What can we do to test the area? We have all developed colds and wake up each morning with terrible congestion, drainage, and headaches. - Rosi B.

Reply: Red Flags about Mold-Suspect Apartments

There are a few things an experienced investigator hears that trigger a sort of "red flag" or prejudiced expectation of trouble, including basement+apartment+waterfront. The worry-o-meter points up a bit more for "mold allergies"
and more for "septic odors".

You are describing at least two possible problem areas: mold and sewage pathogens/sewer gas. And there could be serious health risks. Notify the landlord in writing of your concerns immediately. You can hire an experienced environmental investigator (search our website for "Mold and Allergen Inspectors & Testing Consultants" for a directory that might be helpful. Discuss the inspector's experience, and the extent of actual inspection, not just "testing" before hiring someone. Tests performed without an expert inspection are not worth much.

Question: Windows as a source of mold contamination:

How can I Tell if a Window Leak Has Caused A Mold Problem in My Home?

I had energy efficient windows installed in my townhouse over a year ago. This past spring one of the master bedroom windows leaked after a rain storm because the caulking failed. The company immediately came out and re caulked the window and it hasn't leaked since. My concern is that I now have a water stain under the window on the drywall, and since I have a mold allergy, I'm wondering if there might be mold on the inside of the drywall.

I read your article on testing the dry wall but as mentioned in the article would rather not cut into it unless it's necessary. I looked at other articles but didn't see one with a picture resembling the water stain I'm concerned about. What would you recommend? By the way, this is a very helpful website. I was considering using ozone for any possible mold in my place but see from your article that's not a good idea. Thank you. - G.N.

Reply: Follow the water, estimate the risk, decide if an expert inspection is needed, don't just "test" for mold

A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem with mold, hidden mold, and with tracking down just how much water leaked into the building and where it went. Indeed a basic axiom in deciding the level of risk of an actionable hidden mold reservoir is to identify places where water has leaked into the building, asking how much water leaked where for how long and just where did it go in the building? Follow the water.

That said, here are some things to consider:

First, how disappointing that your new windows leaked - certainly a wet wall below a leaky window is not particularly energy efficient, and indeed it could become a mold reservoir.

Second, the risk of a mold problem that you can't see but that is significant enough to merit removal is not something I nor anyone should guess at by email with so little information. In the article above at MOLD / ENVIRONMENTAL EXPERT, HIRE ? we give some suggestions on how to decide if it's justified and appropriate to hire someone to perform a more competent mold inspection at your building. Testing alone is not reliable.

Third, I would not rely on "mold tests" alone to decide if further investigation is needed. A "mold test", especially an air test for airborne mold, performed without an expert diagnostic inspection of the building is just not reliable in cases where the result is "negative".

We have been sick since moving in to our apartment. The landlord is replacing leaky windows but we want to move out

We moved into a basement apt last nov and both scott and myself have been on and off sick ever since we moved in, we had management come to investigate the problem and so now they are going to replace the windows, my question is this, by replacing the windows, which were the main causes of mold in our apt, i know its in the carpet and in the walls, we both suffer from hiv and we want to move out of this place, how do we go about getting out of our lease without getting taken advantage of?

our lease is up oct 31 and we cant stay that long, we have already applied for a new apt in a different area and got accepted and plan to move out on sept 10th,our lease agreement states that if we break our lease we will have to pay 1 and a half times our rent which is about $1500 and we just cant do that, what advise can you give us before we go and give our notice? please advise, thank you
clay and scott

Reply: Look at more than just leaky windows when tracking down mold contamination

I would NOT assume that your windows were the main cause of a mold problem, though certainly leaky windows or lots of condensate running into walls could be significant. Often a basement apartment has a history of leaks into walls, sometimes prior floods or water entry, and thus there is a risk of larger hidden problem mold reservoirs that can be found by an expert who combines visual inspection, history taking, and strategic testing, perhaps even some careful looks into wall or ceiling cavities in highly suspect areas.

As tenants you may have trouble with the cost of a competent inspection (about as much as your rent) and with the need for invasive measures. If you've notified the landlord in writing and no one will act, and you want to move, you need to consult a real estate attorney. Typically the combination of actual credible evidence of a habitability issue that the landlord won't or can't address is enough to justify breaking a lease.

Beware: if your apt is really moldy your possessions may need to be cleaned before importing them to a new home.

Question: My mold expert passed my home after a mold test but I keep smelling mold. How do I find where the smell is coming from?

Thank you for your excellent site! I am in a quandry about mold testing & remediation. We live in a relatively new home (about 10 years). Because I suffer from allergies & sensitivities, we had this house thoroughly inspected when we purchased it 7 1/2 years ago, by both structural inspectors & an environmental inspector (for mold & radon); both inspections were passed easily, and the environmental inspector's report called our home "one of the cleanest" he had ever tested. But I am now (and for some time) smelling mold. Nobody else does, but everyone knows that my nose knows. We have had several inspections done by various professionals, and so far we have found and corrected 2 small leaks and small mold problems ... but I still smell mold.

The only possible source I can imagine is the cathedral ceiling, which we cannot inspect properly because there is no attic there. The attics on the sides of the houses have been inspected & seem clean, and the roof has been inspected and declared good, no leaks.

One friend has suggested that perhaps there is simply inadequate air circulation in the cathedral ceiling which allows some mold growth in the insulation. We have had an infrared camera inspection, and no obvious leaks/cold spots were found (but some vaguely cloudy areas that the operator could not interpret). I have called more mold inspectors, who want to do very costly sample testing. I don't see the point: I smell the mold, I want to know WHERE it is and get rid of it; I don't really care what kind it is.

So, my question: Can we simply seal the attic/ceiling to prevent air infiltration and avoid ripping out the entire ceiling of our home? If not, what can we do to reliably verify if this is the source of the smell, or where else there could possibly be mold, other that ripping out our ceiling? Thank you! (And apologies for the long & disjointed letter)

Reply: how a mold expert decides where to make a test cut

Lisa, if you smell mold, there is probably a mold contamination source to be found and remedied. It may be possible to home in on the problem if your "expert" really is one - someone with both training and experience in finding building mold. We use a combination of case history, occupant complaints, and a thorough visual inspection of the building for history of leaks, likely moisture problems, and similar clues to identify the "most likely" areas of hidden problems that justify further investigation - often by a small test cut into a cathedral ceiling to use your example.

Your description of your "experts" makes me wonder about the services you received: I wouldn't expect an experienced professional to "pass" or "fail" a building. Those terms are simply too much of an over simplification; most experienced inspectors speak with more caution, and will tell you whether or not they were able to find evidence of a problem that merits further investigation or not.

I would not just "seal" the ceiling as a mold "cure" without first finding out where the problem mold is, how large the mold reservoir is, and what caused it. Why?

So first let's find out if there is a mold problem that needs removal and find out if there is a roof leak that needs repair.

Question: for a Moldy school in Tulsa, I Have a Free Mold Kit - where do I send it?

I have a mold kit that someone gave me but it does not have an address where to send it for results. I work in a school that I understand is infested with mold but they have yet to do anything about it. I have been in & out of doctors offices & the hospital with symptoms that are believed to be from the mold, & the only mold I am exposed to is here at my school. I have always been extremely healthy, but now suffer with asthma & allergies due to mold. In fact, I have to go to an ENT for weekly injections for mold. I don't mind paying for the test, even though my school should be ultimately responsible. Can you help me? Please!!! - Anon., Tulsa


A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem with building indoor air, with visible or hidden mold or other contaminants, and with the cause and remedy that should be understood and acted upon - not things you can decide from a mold test kit. That said, here are some things to consider:

You can send your mold test kit to any mold test lab - most of them anyway - will accept it and charge you an analysis fee. But you should realize, especially as you express health concerns, that "test kits" for mold are basically unreliable when used in the absence of an expert onsite inspection, occupant interview, case history. Only about 10% of molds will grow on any culture whatsoever, so you're about 90% wrong when you open the box. Details are at Mold Culture Plate Test Errors.

Therefore if you or others have reason for serious concern about mold and indoor air quality in your workplace, it seems to me smarter to be sure that a competent expert is engaged to help assess the situation. To avoid any appearance of conflict of interest, having given the advice in this note, that is not a service that we would provide.

Above beginning at MOLD / ENVIRONMENTAL EXPERT, HIRE ? we provide advice that can help you decide if hiring a mold expert to inspect, interview, and perhaps conduct some testing is appropriate.

Question: I had a house air test for mold and Asp/Pen was 920 and 644 and 2850. There is no visible mold. Should I be concerned?

I recently had a air quality sample done of our house. Asp/Pen outside was 920, on the first floor it was 644 and in the basement it was 2850. There are no visible signs of mold. Should I be concerned and do I need a mold remediation specialist? It's a finished basement.
thanks! - John G. 10/7/2011

Reply: If your mold inspector is not answering these questions, what was s/he paid for?

John, my best advice on deciding if you need to hire a mold investigator or mold specialist is summarized in the article above. There you'll see that we list a variety of factors one would consider in making a decision to go further or not. Depending on various factors such as occupant health risks, building complaints, visual observation of water or leak history, etc., even a small visible mold colony could prompt further investigation.

Your high indoor Pen/Asp count is roughly 3x the outdoor count (and of course the outdoor count might not even be the same mold spores as found indoors) and your basement count is highest, suggesting that if there is a substantial problem mold reservoir that's where to start looking. That alone might be enough to prompt further inquiry.

Did you ask the expert you paid to perform mold tests for an interpretation of the rest results? If not, you're not getting what you paid for.

Question: moldy basement "rafters" (ceiling joists)

I was wondering I could email you a few photos of my basement rafters (I can not figure out how to attach the photos to this comment). The area is below my living room (no overhead water source) and this mold-like staining is on several rafters intermittently, as there are rafters between the stained ones that have no visible mold.

There has been no water intrusion and the rafters have been dry. In the room is our HVAC and other mechanicals. I have reviewed your articles and it seems like it may be the cosmetic variety that is harmless. However I do notice a moldy odor in the basement during the rainy/humid seasons. I am getting conflicting ideas based on your articles about mold odor meaning there is definitely mold that should be dealt with and cosmetic mold. - Anon 12/26/11

Reply: guard against spending large sums on cosmetic, harmless indoor mold

Mold on basement rafters?

We would be glad to take a look at photographs that help explain a question you pose to InspectAPedia experts. Use the CONTACT links found at the top or bottom of our web pages. While examining a photograph is never a substitute for an expert on-site inspection, and while often an expert will find important conditions that a layperson may have not noticed, photographs do provide excellent information that can often allow us to make useful comment.

Question: we have been constantly sick, my mold inspector didn't find anything, but based on 300 spore/M3 of air the inspector called for $2000. worth of remediation

I and my kids have been sick constantly for the past 4 months with respiratory issues. My husband thinks it's just because my son started preschool but I was concerned so I hired a professional to do a mold inspection and test. The inspector found no visible sources of mold, water damage, etc. He thought our house was pretty clean.

But then the air samples he took came back from the lab with around 300 count of Penicillium/Aspergillus mold spores in the bedrooms where the samples were taken. The final report called for $2000 of professional remediation cleaning of the bedrooms using HEPA vacuuming, etc from their company to solve the problem solely based on the air samples taken because the inspection otherwise found nothing.

At this point, I"m not sure what to do. I'm not sure whether I should move forward with this costly remediation when there isn't a source of mold found. I'm not sure this remediation of cleaning out the rooms with even make a difference overall. And I'm not convinced we have a problem with an Aspergillus/Penicillium spore count of 300 in the air. If I was convinced then I would spend the money but it's a lot of money for us. I'm not sure what to do. - Felicia 5/29/2012

To clarify a bit further. The outdoor asp/pen count was 90. So the inside count was 3x the amount as outside at 300. But I did read in another inspectapedia article that clean building counts ranged from 250-600ish. I read the article above but am still not sure what to do. Thank you for your help. - Felicia

Reply: first confirm that there is a problem, second find it, third find its cause, fourth remove the problem and fix the cause

Felicia the report and advice you received sound very questionable to me; if there is a high indoor Pen/Asp count then one needs to look for and find the source of that material. Just surface cleaning of exposed areas is premature and a waste of money - it's treating the symptom without finding and fixing the cause.

An expert inspector examines the entire building, inside and out, and when there is no visible mold of consequence, but testing and case history and other observations suggest a mold problem, then s/he looks for and investigates further into the most likely locations of a hidden problem, often by looking at the building leak history or design that points to most likely locations for hidden leaks or moisture traps.

Watch out: For an article with many examples of how one might interpret various mold inspection or mold test results with different "spore counts" take a look at MOLD EXPOSURE STANDARDS. But keep in mind that very trivial changes in how a "test" is conducted can result in several orders of magnitude difference in the "count" number obtained, and worse, some tests that detect mold are detecting the mold that liked a culture not the mold that is a problem in the building.

1. Comparing indoor to outdoor mold spore counts, while a common practice, is highly unreliable as it's often comparing apples and oranges. For example outdoor Pen/Asp could be a completely different genera/species than the indoor mold, thus making their comparison irrelevant;

Also even very low spore counts can indicate an indoor mold reservoir in certain cases, such as finding Pen/Asp spores in connected spore chains.

2. Please take a further look at the article above, including the FAQs section, intended to give you some criteria to help decide when it is justified to dig further into this question for an individual building. Then let me know what questions remain.


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