Building Science 4 Dummies: Mold

Just mentioning the word mold or as it is known across the pond as “mould” is enough to send some people directly into panic mode. With the toxic mold scare from years ago many insurance companies (especially after losing millions) no longer cover mold damage or remediation as they consider it a “maintenance” issue.

There’s Good Mold and There’s Bad Mold

Mold is one of the most common items found on this planet with the four most common types found in buildings being Cladosporium, Penicillium, Aspergillus, and Alternaria. The second most common one… yep, that is what penicillin comes from. For those of you who like bleu cheese or a glass of wine, well the “bleu” is a mold & the reason your wine tastes so good is because of mold. The “bad boy” that caused such a panic is called Stachybotrys Chartarum which is a dark greenish-black color & loves wet paper, dust, & wood products.

There is no such thing as “toxic” mold, as the mold itself is not actually toxic or poisonous.  With that said certain molds are toxigenic, meaning they can produce mycotoxins. Because mold is everywhere & there are so many types, the EPA, CDC & other organizations do not have guidelines or standards on what is considered acceptable, tolerable or even normal.

 Should I routinely test?

No it really isn’t necessary as one will find mold everywhere. With that said if you only start showing (or they become more pronounced) allergic reactions like irritation of the eyes, nose, or throat when you are at home it might be worth checking out after visiting your doctor. The same goes for flu-like symptoms like fatigue, dizziness, & headaches or a worsening of your asthma conditions.

Minimizing Mold Growth

Mold being a natural byproduct of the fungi family that reproduces via spores that can remain dormant, yet viable, for many years. Just like every other living thing they can only grow & thrive when it has a food source & moisture. It would be impossible to eliminate all food sources, but if you eliminate the moisture, it can’t grow & goes dormant. The best way to do this is pretty simple; keep up on your houses maintenance and run your exhaust fans during & after your showers.

In some cases, especially in humid climates this might not be enough so consider;

  • Air-sealing your house helps eliminate humid  air from getting in
  • Consider installing a dehumidifier
  • Do not turn your air conditioner off for long periods of time as this will allow moisture levels to climb inside the building allowing mold to get a foot-hold
  • Install insulation on cold water lines & ducts to help prevent condensation from forming
  • Wipe down your sinks, showers, tubs and other wet areas to eliminate standing water
  • Be careful of how many potted plants you keep in the house
  • While this falls under maintenance it is worth a reminder – inspect the building exterior at least once a year and repair caulking, roof flashing, and any breaches in the building envelope

Cleaning up mold:

For most of us, we aren’t going to have any symptoms & we will spot maybe a small area around a shower or sink.  In these cases a regular household cleaner listed to kill mold is a good choice or you can mix up one cup of bleach to a gallon of water. Whatever you do, do not try to sweep it away, vacuum it up, or rub with a dry cloth as you will be spreading it– lightly dampen it & then wipe it up with a wet cloth.

In some cases you may have some on some drywall, or other porous surface & using bleach or other chemicals won’t kill all of it (just the surface layer). Depending on the circumstances & amounts you might need to bring some professionals (especially if one is having health problems). For drywall; if it is a small area, you can use bleach to kill the surface layer but you will have to be careful about the moisture content in that area. Below is a picture in infrared showing that even if you clean it with bleach it is still there. Be careful if you do decide to cut out the drywall as you can easily spread the spores throughout the house.

Cleaning your ducts to eliminate mold & reduce dust is one of the biggest scams out there. The metallic surfaces of the ducts & equipment does not normally support mold growth, though dust in them can under the right conditions. As most air blowing through them is dry it is highly unlikely that this would happen. If your house is particularly dusty, sealing up your ducts properlywill help eliminate that issue.If you do have ducts that are excessively dusty, after sealing them up & testing them you can consider having them cleaned. If your ducts do have mold growth, this changes matters dramatically as the last thing you want is a typical cleaning where they blast away with air & whips (remember mold spreads by spores). In this case you need a company that specializes in removing mold with germicides, etc…