GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter X Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Mold Remediation

CMObuilds | Posted in General Questions on

Anyone have mold remediation on a commercial building experience or been/are in the mold remediation industry?

I have a maintenance contract on this building that just started, could smell a strong mildew odor in a unit on the top floor north side of the building when completing a PO. Was doing top floor work in the south side of the building no odor. Slight odor in hall at the midpoint of the building top floor. It was unseasonably warm that day, mid 40’s high temp.

I went into the attic, there is a full height fire wall east and west dividing the building in half, attic access on the south side. South attic was hot, no alarming issues, entire building has 6-8 of old blown fiberglass and is wind washed on the exterior eaves. Hip roof. I could see most light locations, bath fans and other penetration by staining on the fiberglass. No active mold growth was visible.

There was a small 2’x2′ open cut in the attic fire wall to the north side. Right at the hole the smell intesified, went in 10′ and looked around, was like a jungle. Humid, mold running up the top chords, eave edge plywood looks like it has been painted black, all plywood has some sort of staining of various intensity, jack trusses off a girder truss looked soaking wet. Nasty. Obviously informed the owner, its pretty clear the sun is protecting the south side.

Inside the units, electric baseboard heat. Carpet showed damp by electric baseboards when I did a quick scan with thermal cam, took the owner up a few days later and it didnt smell as bad and appeared much drier, this was colder out, sun was setting.

So obviously we need to eliminate moisture source, thats not my worry, the method of cleanup is. Cleanup research is all over the place, some companies use chemicals, some use dry ice, some just scrub, all with negative air and I find differing opinion on the chemical, paint and dry ice approaches from works to makes things worse. Decontamination rooms, clean dirty rooms with no real defination of when one protocol kicks in. Epa protocol and IICRC 520 protocol seems to take 2 different approaches.

Also pretest for spore count or waste of time? we know there is mold. More than one guy the owner has talked to has said just “spray it” and correct moisture issue, whatever the spray they are referring to is. Some say bleach works, other opinion is its hazardous and better methods. Very hard to seperate fact from fiction with this stuff, does anybody have any experience dealing with this? It isnt my liability or property, but I want it done right for the owners sake and have some say in the matter being the “construction guy” who will put everything back together once it is remediated, trying to figure out the correct definition of “mold remediation”, a lot of companies seem like snake oil salesman with the franchise systems. We are talking over 1000 square feet pretty black sheathing under a 10 year old roof plus thousands more of various stages of staining and hundreds of feet of what looks like white fuzzy mold running up top chords, obvious liability issue to owner and Id rather not have some clown attorney trying to tap my GL limits, so it seems somewhat of a sensitive situation.

Moisture source seems to be a combination of ice dams, ventilation fans dumping into the space, lack of upper ventilation (hipped roof), and possible roof leak, very few proper vents. Insulation levels are equal both sides.

Comments appreciated.

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. GBA Editor
    Martin Holladay | | #1

    T. Carlson,
    Here is a link to one of the best (most authoritative) guides to the topic:
    Mold Remediation in Occupied Homes.

  2. CMObuilds | | #2

    Thanks Martin, I missed that one.

    I did read RR-0208: What You Need to Know About Mold, which was written in the same year, 2002, and noticed that article mentioning a lot of unknowns regarding health, wondering if the testing has gotten anywhere in 16 years?

  3. CMObuilds | | #3

    Nobody has dealt with remediation?

    Curious seeing as though this website flirts with creating it unintentionally, someone must have come across it in a more serious situation.

    I'll share what I have learned thus far from various sources both online and from companies and insurance companies via telephone:

    First off, I'm guessing most people don't say anything and remediate themselves. Scrub it off to sell.

    Mold is everywhere, testing for mold will always be positive. Health effects are unknown, the industry is primarily based on junk science. Mold needs moisture, eliminate the moisture is one of the only consistent statements I can find, although obvious.

    So my big question was, eliminate the moisture, why bother with cleanup, wont the mold die? According to an environmental tester, yes. So why clean it up then?

    Thus far, this entire industry is basically a pay for taking liability venture. People get freaked out by mold, it makes your attic look terrible, it kills real estate deals, it heightens lawyers senses, but eliminate the moisture and there is no more mold growth. Do the spores and their potential potency remain a problem if you don't scrub it off sheathing? I don't know, yet.

    But, what seems to coming clear is the fogging, dry ice, sealers, fungicides, paints, franchise concoctions are a sham designed to milk insurance companies and homeowners for money, make the scary go away.

    Insurance will pay if the damage was recent, if you inherit an unknown problem that was ongoing, or you really didn't know because you don't go up in the attic much, insurance doesn't have to pay, maintenance issue.

    Martin notes a Building Science paper from 2002, I'm guessing they would have deleted or updated it if it became obsolete, yet they haven't, 16 years later! And one of the papers in the series written that year notes how little we know and apparently nothing has changed, no regulations, no licensing except for a few states yet if I touch it and someone claims they developed respiratory problems I could get sued. My GL policy excludes it, so if I am in the vicinity and want to protect my business assets I have to enter a complicated, tricky world of specialty policies which apparently has problems and gaps of its own. Basically before I go in to restore the construction scope, you hire a fall guy who will go on record declaring the space mold free in exchange for a decent chunk of change.

    Fascinating and convoluted, boggles my mind. If anyone cares, I will update this situation as it evolves.

  4. ohioandy | | #4

    T., thanks for posting your thoughts on this. Everywhere and convoluted, for sure. In this field we all deal with the specter of mold constantly, but I expect most of us on this site are in the business of prevention, not remediation.

    Moving slightly off your topic, my contractors' liability policy has a paragraph that seems to exclude ALL mold issues caused by faulty workmanship; when I asked my agent about it she said, "oh, no, don't worry about that. Mold is covered."

    I came across this alarmist piece about mold in heat pumps, from the CBC north of the border:

    Has anyone else seen mold-infested heat pumps? Mine aren't. They've included a single picture as evidence of the problem, but it shows about as much mold as most people have under their toenails.

  5. GBA Editor
    Martin Holladay | | #5

    T. Carlson,
    The authors of the paper I linked to are all straight shooters who give good advice, based on science and field experience. I don't think that the fact that the paper was published in 2002 invalidates their advice.

    In addition to the practical questions answered by the authors of the paper, you have legal and insurance issues to consider. For those issues, talk to your insurance agent or a lawyer. Good luck.

    1. andyfrog | | #8 Here's some interesting info from an environmental scientist

  6. CMObuilds | | #6

    Andy, what class/trade policy do you have? Trades that really wont have mold exposure get coverage. My GC policy will not since Im more likely to encounter/disturb mold. I need a Contractors Pollution Liability policy with a mold endorsement, which I can get per project or term though it's pricey and there still seems to be holes in it.

    I went in to assess the damage and determine the source, humidity was around 60%, sheathing was solid, a few sheets lost some integrity and dip when you step on them but no rot. It appears bath fans dump into the attic space, there was/is a roof leak, massive air leakage from below, no poly, open soffits and tons of penetrations with sizeable gaps. It was cold out and I was sweating my cajones in a tyvek suit which should not be occuring this time of year.

    So the big question is still clean the mold thoroughly or go basic?

    I already have the scope of work to deal with air seal and thermal issues, but either the black sheathing needs to get pulled now or he leaves it, I do my thing to repair everything but, and it gets replaced at the next reroof. Either way, our work is in a negative pressure environment vented outside although I probably wouldnt run a recirculating scrubber, just negative air.

  7. CMObuilds | | #7

    Little update.

    We pulled the roof sheathing, dealt with extremely leaky exterior wall, put in proper vents then laid new sheathing down and reroofed it. Then treated the attic and brought an R19 ceiling to R50. Then we got 20+ inches of snow. Not an icicle on the north half, south half which we did not touch, had icicles all the way around, sucess. No proper vents to seperate the warm insulation from the roof deck and major heat loss at the exterior wall plus about 64 sf of wide open kitchen soffit, hundreds of feet of wall plate leakage, oversized wire holes and a wide open party wall all kept dumping heat and creating condensation on the sheathing.

    All for less than a restoration company "remediating" the attic with a fungicide and no thermal improvements. That industry is a joke.

  8. AbdulHaseeb22 | | #9

    I appreciate your concern regarding mold remediation on a commercial building. Dealing with mold issues requires careful consideration and proper techniques to ensure a safe and effective cleanup process. Based on my experience in the mold remediation industry, here are some insights and recommendations for your situation.

    First and foremost, it's crucial to address the moisture source causing the mold growth. As you mentioned, ice dams, ventilation issues, and potential roof leaks could be contributing factors. Resolving these issues is essential to prevent future mold problems.

    In terms of the cleanup process, there are various approaches available, but it's important to consider the specific circumstances and the extent of the mold infestation. While some companies may advocate for chemical treatments or dry ice blasting, it's essential to approach these methods with caution. Chemical treatments should be carefully chosen, as some products may have adverse effects on occupants or the environment. Dry ice blasting can be effective in certain scenarios, but it may not be necessary or suitable for every situation.

    In many cases, a thorough scrubbing of affected surfaces combined with proper containment measures and negative air setups can yield successful results. Using high-efficiency particulate air (HEPA) filters and following industry guidelines for containment can help prevent the spread of mold spores during the cleanup process.

    Regarding the pretesting for spore count, it can provide valuable information about the extent of the contamination and guide the remediation process. However, it's important to work with qualified professionals who can accurately interpret the test results and determine the appropriate course of action.

    To ensure a comprehensive understanding of mold remediation, it's advisable to consult reputable organizations such as the Environmental Protection Agency (EPA) and follow their guidelines. The IICRC S520 Standard and Reference Guide for Professional Mold Remediation can also serve as a valuable resource, providing industry-accepted practices and protocols.

    Considering the sensitivity of the situation and potential liability concerns, it's crucial to collaborate with experienced and reputable mold remediation professionals. Look for companies with a proven track record, certifications, and positive customer reviews.

    In conclusion, addressing the moisture source, utilizing proper containment measures, and employing effective cleaning techniques are key components of successful mold remediation. By following industry guidelines and working with experienced professionals, you can ensure that the process is carried out efficiently and safely.

    For additional insights on mold removal, you may find my article on "DIY Mold Removal Solution" helpful. It discusses various do-it-yourself approaches that can be effective for smaller-scale projects.

    DIY Mold Removal Solution
    Please feel free to read the article for more information.

    I hope this information helps you navigate the mold remediation process effectively. If you have any further questions or require clarification, please don't hesitate to ask.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |