MOLD: Problem? or NOT?
I've been a microbiologist since 1979 and my company has performed over 10,000 mold inspections……so I’ve seen plenty of furor over fungi! Sometimes, to a Realtor or home owner, it may feel like the most dangerous thing about mold is the inspection. Unfortunately this is often true. Since there are no Federal or State agencies regulating mold inspections in Florida, anyone, regardless of qualifications, can be a mold inspector (and anyone with a printer can be a “Certified” inspector). This is the reason that approximately 30% of our company’s business is redoing mold inspections for the seller after a deal has fallen through, or is about to, due to a bad mold inspection. The majority of these homes had no real mold problem. The problem in most of these cases was the inspectors not understanding the difference between the simple presence of mold spores in the home and actual mold growth in the home.
Since mold spores are everywhere, it is perfectly normal and expected that there will be some mold spores in every home. Mold spores are not the problem; mold growth is the problem. However, the two most common sampling techniques used by most mold inspectors usually wind up identifying a problem where none exists. One of these is swab sampling, where a cotton swab is rubbed across a surface, inserted into a vial of growth media, and sent to the lab. Any viable spore will grow in the media even if it wasn’t growing in the home. Now you have a report indicating a problem where one might not exist. The most popular sampling technique is air sampling, which has its place in a comprehensive inspection, but not as a stand alone method, which unfortunately is too often the case. The problem with air samples is that the lab report will tag a sample as a problem if the number of spores in an indoor sample is greater than the number in the outdoor sample. Unfortunately, the number of spores outdoors will fluctuate tremendously depending on the season, the weather and even the time of day. For example; an indoor sample taken on Monday has a spore count of 500 and the outdoor sample has a spore count of 1000. Great, no problem indicated on the lab report. Take the same two samples on Tuesday after it’s rained. The indoor sample is still 500, but now the outdoor sample is only 200. The lab report from Tuesday’s sampling tags this as a problem even though the conditions inside the home have not changed.
A good mold inspection uses a combination of methods to accurately determine if there is mold growing in the home and will include ALL of the following:
- Tape slide samples from any visible mold or water stained areas. When examined under a microscope the presence of hyphae will tell the microbiologist if the mold is actually growing in the home.
- Moisture readings should be taken around all doors, windows, plumbing and any other areas of possible moisture intrusion.
- If high moisture areas are found then interstitial samples should be taken from inside those wall cavities to assure that mold growth is not occurring, unseen, inside the wall, which is very common under windows and around plumbing.
- All A/C units should be sampled.
- Finally, air samples should be taken from all rooms and outdoors as a background sample.
The report is just as important as the inspection. Most inspectors simply hand over the lab report, without any explanation. If a sample is tagged as a problem, the fine print on the lab report suggests that you contact an indoor air quality expert (not the lab or the inspector!). That is when the Realtor or seller winds up calling my company for help. A good report should include not only the laboratory results, but professional conclusions based on those results. And finally, no mold inspection report is complete without specific recommendations as to what to do about any problems that were identified.
Current Regulations
Currently there are no EPA or State of Florida certifications for mold inspection or remediation companies. Texas is the only state that has passed legislation regulating the mold industry. In 2005 both the Florida Senate and House passed HB-315 which would have provided Florida consumers protections similar to those of Texas, but the legislation was vetoed by Governor Bush after heavy lobbying from the currently unregulated mold businesses in Florida.
HB-315 would have made the following currently common practices illegal:
- Conducting Mold Inspections without a College Degree
- No more unqualified inspectors claiming they are “certified”
- Conducting Mold Inspections without $1 million in E&O Insurance
- This insurance is not even available to the unqualified
- Remediation Companies conducting mold inspections
- Obviously a conflict of interest
- Remediation Companies Conducting Their Own Clearance Testing
- Again, a major conflict of interest
- Continuing Education Courses to be taught by non-profits only
- No more “certification” mills churning out unqualified inspectors after only hours of training.
- Training must be conducted by a University, Medical School or other not-for–profit training provider
Imported Chinese Drywall
During a domestic drywall shortage from approximately 2004 to 2007, an estimated 320 million square feet of drywall was imported from China. Some of this imported drywall has been off-gassing volatile sulfur compounds which can produce a rotten egg odor and which is corrosive to bare copper. So components like A/C coils, refrigeration lines, plumbing lines and electronics have been failing at a higher than normal rate in homes containing this drywall. This is the most common symptom of the problem, and the only one to date that has been scientifically linked to the drywall.
Drywall is made from gypsum, which can be naturally mined or synthetic. The synthetic gypsum is made from a byproduct of power plant air scrubbers. The first theory was that the Chinese drywall was contaminated by fly ash, another power plant byproduct. But it turns out that the problem drywall was actually made from naturally mined gypsum which has been traced back to mines in the Shandong Province of China.
So far no one is sure what is causing this off-gassing. The U.S. EPA, Florida Department of Health (FDOH) and drywall manufacturers have all done comparison testing on a very limited number of samples of Chinese and domestic drywall. They found that when subjected to elevated heat and relative humidity in an environmental chamber the Chinese drywall produced two volatile sulfur gases which the domestic drywall did not; hydrogen sulfide (H2S) and carbon disulfide (CS2). They also found that the Chinese drywall contained several other compounds that were not present in the domestic samples. These are iron disulfide, strontium sulfide and some organic compounds.
None of these tests has determined what the actual component is that is causing the off-gassing. There’s speculation that it might be coming from the iron disulfide or strontium disulfide, or that fumigation materials may be reacting with the organic compounds….no one knows right now.
Our inspections to date have found, not surprisingly, that there is a direct correlation between the amount of copper corrosion and the amount of Chinese drywall in the home. Rarely have we found homes where all of the drywall was imported. Normally there is a combination of domestic and imported drywall. This is because drywall is a commodity. Builders order it not by brand, but rather based on the specifications required for the different applications present in every home (i.e.; ceilings, walls, high impact, mold resistant, etc.) When a warehouse receives the order they simply send whatever brands they have that meet those specifications. We have seen as many as five different manufacturers’ products in a single home.
There are no Federal or State regulatory guidelines for conducting these inspections. So it’s important to have one done by someone who understands the science and can provide a comprehensive inspection.
The procedure we use is based on the analytical data collected from the studies conducted to date by the Florida Department of Health, EPA, and the drywall manufacturers. It uses all of the currently available indicators to determine the presence of Chinese drywall.
- A boroscope is used to inspect and photograph labels inside the wall cavities to determine if the drywall is domestic or Chinese.
- The attic drywall is also inspected because ceiling drywall has different specifications than wallboard and often has a different manufacturer.
- Non-insulated copper components throughout the home such as A/C coils, refrigeration lines, plumbing and ground wires are inspected to identify any corrosion. Since Chinese drywall can be present in only a portion of the home, every room is inspected for copper corrosion (every room has copper ground wires in the electrical outlets).
- If copper corrosion is found samples of the corrosion product is collected for laboratory analysis to determine if the corrosion is caused by sulfur…this is important because corrosion in the home is normally caused by oxygen, not sulfur, so just the visual presence of copper corrosion is not enough to determine if it was caused by Chinese drywall.
- Interstitial air samples for the volatile sulfur compounds H2S and CS2 are taken from inside wall cavities where gases should be most concentrated. Air samples are not effective in determining the presence or absence of Chinese drywall because the sulfur gases dissipate. Our inspections include air samples only to determine that the H2S and CS2 concentrations are below regulatory limits associated with health affects.
We are closely following the EPA, CPSC, CDC, FDOH and industry research, and will be amending this procedure as new facts come out.