Mold Matters

The Importance of Indoor Air Quality

November 1, 2023

It takes most homebuyers mere minutes to decide whether their prospective home has sufficient light and good air. I have seen them turn right around and walk out if the home is musty. And as a mold inspector, I have encountered frantic people who are deathly afraid of the stuff. Their first question is usually, “Does my house have mold in it?” That’s an easy one. Yes, it does. BECAUSE THERE IS MOLD EVERYWHERE.

UNDERSTANDING MOLDS

Some molds can cause disease and even be toxic to some people. It all de-pends on your individual immune system. I’m OK with most of them but Chae-tomium really gets to me. It is white and grows on wood joists and furniture in damp basements. I can tell it is above me without looking. The most common molds are Penicillium/Aspergillus. This is the stuff that grows in wet basement corners with un-extended downspouts draining right to the foundation. It also grows outdoors on flat-painted surfaces, and in bathrooms. In these cases it can be prevented with semi-gloss paint.

Stachybotrys is the fabled “black mold” (lots of mold is black in color), which usually shows up in full force after floods—natural or from plumbing. It is one of the molds that can cause illness.

Mold is a fungus. Fungi release spores to reproduce. They have root-like struc-tures called mycelium that can grow one-sixteenth of an inch into wood. Mold needs to be treated with a sporicide—either bleach or hydrogen peroxide based—and scrubbed hard to remove the mycelium. Dead spores can still be irritating, so affected rooms need to be cleaned with a HEPA vacuum. Mold re-mediation companies literally paint all non-porous surfaces with sporicide. It is extremely expensive.

Mold in attics is usually caused by lack of soffit and/or ridge vents, moisture intrusion from outside, or bathroom fans vented to the attic. Not enough insulation can also be a problem. It is a matter of dew point. Warm, moist air hitting cold surfaces causes condensate to form. Mold forms in the winter when moist air from the living space hits the cold sheathing. (Those thermostatically controlled fans don’t prevent mold. They mainly draw conditioned air from the living space—hence the absence of them in new homes.) Ideally, any air from the house would go through enough insulation so that, by the time it entered the at-tic, it is almost the same temperature as the outdoor air.

The silliest way to test for mold are these tape strips you then send to a lab. These give you no indication of the extent of the problem. The only way to effectively identify the type and quantity of mold present is to take an air test with a control. The machines send a given volume of air over a sticky slide that then gets sent to a lab that identifies what kinds and how much mold there is. The indoor samples are compared to an outdoor (control). You can’t fault the house if your outdoors is extremely moldy. My Mold Detective provides a very reasonable system.

These encapsulated crawl spaces require the cooling system to be on all the time in the summer. Imagine my surprise when I entered a beautifully encapsulated crawl space in a new house for sale and it was literally raining. Note the mold on the brand-new joists.

MOISTURE

Neither mold nor termites can thrive without moisture. If you have a dry crawl space, it’s probably safe. If it’s damp, the health of the whole house can be affected. I recently inspected one home that was in bad shape (no vapor barri-er, poor grading, downspouts draining to the crawl space, vents below-grade, overflowing gutters), and the interior living space above was very humid.

The best way to treat a crawl space is as a mini-basement. It’s called encapsu-lation. Instead of insulating the floor joists and having open vents, an antimicro-bial vapor barrier covers the floor and runs up the sidewalls that have been in-sulated with foam board, and then an HVAC register is opened. This makes it possible to inspect and service the joists, ducts, and electrical and plumbing fixtures.The joists and ducts stay nice and dry.

VENTILATION

Eliminating moisture problems also involves good ventilation. Many folks use dehumidifiers in their basements. These are reverse air conditioners and can use $500 of electricity per year. They just remove moisture from the air; they don’t move any. I always recommend a humidistat switch on the basement bathroom fan. These move hundreds of cubic feet of air per minute and there-fore move out spores and stink and draw fresh air down.

If there is no bathroom fan, one can be installed anywhere in the basement for the cost of about one year of running a dehumidifier. There are other, more cost-ly systems, but they aren’t any more effective.

Another option for better basement ventilation is adding HVAC registers or at least not closing any of them in the basement. The trick on a hot night is to turn the HVAC fan on instead of to auto so cool air from the basement can be drawn upstairs.

You could also add a return in the basement if there is a forced air system.

Some of the older houses have no forced air systems, maybe nothing in the basement, and radiators everywhere else. Other houses have an old radiator system and a new forced cooling system on the upper floors. These systems can just have heating elements installed and then you can ditch the radiators. Additionally, the cooling unit’s fan can be run periodically in the winter to pro-vide filtered, circulated warm air.

The new high velocity forced air systems can be installed on older homes with little demo due to the three-inch duct pipes used.

Listen up! Some may find me cute, but beware: My feces harbors a dangerous ringworm.

DUCT CLEANING

A study done by The Washington Post indicated that stuff in HVAC air ducts tends to stay there and, therefore, duct cleaning is not very important (except for dryers). It actually makes the house very dusty. I recommend duct cleaning if it’s been 40 years, there was a mold event, or if racoon feces were present (found a big pile myself once!) Racoon feces harbors a dangerous roundworm.

Eighty percent of households throw out their ionization smoke detectors because they go off when you cook.

GAS AND AIR QUALITY

Everyone seems to want a gas stove, but the new ceramic cooktops get really hot really fast and are much easier to clean (there’s a nice Weiman’s cleanser I recommend).

Eighty percent of households throw out their ionization smoke detectors because they go off when you cook. The new photoelectric ones are much less responsive to cooking odors and could save you from dying of smoke inhala-tion.

In addition, new research indicates some cases of asthma may be caused by gas stoves. Gas stoves can add nitrous oxide, carbon monoxide, carbon dioxide, moisture, and particulates to your home. They are hard to clean and dan-gerous, as many stoves allow for the gas to be on without igniting. They also foster global warming. Let’s say goodbye to gas.

OTHER SOURCES OF STINK

I just inspected a house where the owner only felt sick in the kitchen. It turned out there was a floor drain at the bottom of the basement stairs leading up to the kitchen. It had a dry trap so sewer gasses were floating up to the kitchen. These can really mess with you. We poured a bucket of bleach water down it and added a chaser of vegetable oil to slow down the evaporation for next time. You can find dry laundry traps often.

My favorite story of bad smells entails some tipsiness as my inspection got to the two-hour mark. I felt like I had a hangover. No one else noticed anything amiss, but I knew something was off. It was in the basement where I felt it strongest, like it was coming up through the concrete floor. Indeed, a full oil tank had leaked in the ground outside. I recommended an air filtration system that conserves heat transfer. The sellers installed one and raised the price $10,000.

HVAC TIPS

  • Every home for sale should have the HVAC fan running constantly to avoid any stale air.
  • A clean filter should be put in and the grease filters on the draft-hood should be cleaned; just put them in the dishwasher. Cut-to-fit washable filters are my choice because they never restrict air flow. A clogged paper filter en-courages mold.
  • I am not a fan of whole house humidifiers because you can’t keep track of the over-moist areas or see moldy media. Just use room humidifiers during the cold season.
  • The UV lights kill microorganisms indiscriminately. They may actually kill more good bugs than bad. The balance is important. We consist of more bacte-rial and virus cells than our own. As a reference, a two-inch circle on your body has about 180 different species.
  • Anyone with allergies should have dust mite covers on their pillows and a mattress cover. And it’s best not to have carpeting. Wash pillows every six months. Buy a nice HEPA air filter for the bedroom. I recommend Oransi.

Before you worry too much about the health of your house, take good notice of what’s happening outside. If lots of people are sneezing outside your house, don’t blame your home for your misery. However, in most places, outside air is better than indoor air, so open some windows. It’s inspirational!

Opinions or statements of authors are solely their own and do not necessarily represent the opinions or positions of ASHI, its agents, or editors. Always check with your local governmental agency and independently verify for accuracy, completeness, and reliability.


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