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When to hire an expert: this article describes how to determine that you should hire an expert for on-site mold or other indoor contamination inspection and testing. Not every mold worry merits a costly onsite investigation - hiring an onsite expert or even performing mold testing for trivial mold cleanup jobs is expensive and usually unnecessary. But failing to hire an expert when one is needed can itself be a costly mistake of a different kind.
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The purpose of the advice below is to help readers decide when it is appropriate to perform mold inspection and testing on a building.
We want to know how and when mold testing is appropriate, and we want to avoid spending money on mold testing when it is not necessary. Also we want to avoid spending money on unreliable mold "tests" and inspections that do not validly support any conclusion about the building.
Our moldy home photograph (left) shows a cup fungus growing along the wall/floor baseboard trim in a home that had suffered a prolonged plumbing leak.
The visible fungal growth is quite obvious. What is less obvious, and what will require an expert inspection, is the extent of mold cleanup needed in the building, possibly including hidden mold in wall and ceiling cavities.
The answer to the "when to hire an expert" question hinges on the answers to the questions given in the table below. Or if you don't like decision tables try our "expert hiring RULES of THUMB" that follow the table.
Five Rules of Thumb for Deciding When to Hire a Professional to Inspect for Mold & Prepare a Mold Remediation Plan
IF these conditions are present in a building being evaluated for mold contamination risk
THEN mold may be a problem in the building. -- N. Carlson, U. Minnesota [Comments added by DF]
Green link shows where you are in this article series.
Frequently Asked Questions (FAQs)
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"
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 EXPERT, WHEN TO 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
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.
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.
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 EXPERT, WHEN TO 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.
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.
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?
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 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.
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