I’ve been perplexed by this issue and I’ve found that it is very difficult to find dependable information on this subject. Part of the reason for this lack of good information is that no one really knows answers with any scientific foundation. I’ve been doing a lot of reading and based on that research, I’ve come to the following conclusions. As you read these, please keep in mind that I am also among the legions of mold non-experts who have voiced their opinions on the subject. But this information was taken from what I thought were reliable sources. Hopefully this will put the mold issue into perspective.

1. You can not eliminate mold in your house. It is always there. So the best recommendation is to control the moisture in the house by keeping the relative humidity between 30% and 60%. Mold needs moisture and it will grow when the relative humidity is above 60% to 65%. Surfaces that have condensation appear on them will be more prone to growing mold because condensation is 100% humidity, of course.
2. There are over 60,000 known types of mold. Only a few are known toxins. The huge majority of them are benign or their effects are unknown. And they live everywhere around us all the time.
3. Testing for mold has a limited value since nearly every test will show some mold. Even the spore count can be deceiving depending on the reproductive cycle of the mold. Some tests can show large releases only to be followed by extended periods of dormancy. Testing should be done on the outside of the house as a point of comparison. It is possible that similar levels of mold exist all around and the amount found in the crawlspace do not represent anything abnormal. Even the State of California Department of Health does not recommend testing for mold contamination because of the lack of standards for judging what is an acceptable quantity of mold! From what I’ve read, the only way to know if you have too much mold is if you can smell it or see it. Even then, the odds are highly in your favor that the mold you smell is not harmful since the vast majority of mold is not harmful.
4. Most molds produce volatile organic compounds (VOCs) that become airborne and smell musty. These are offensive, but are not thought to cause illness. Some molds, at certain times do produce toxic chemicals called mycotoxins. If inhaled in sufficient quantities, some people can get sick from these. But this is not an established risk for healthy people. It is more likely in people with weakened immune systems.
5. Molds can trigger asthma attacks or hay fever, but there is no proof that molds cause these ailments. The only cases of molds causing infections in humans are rare and only occur in people with a weakened immune system.
6. Mold can grow on any surface. Metals and other non-porous surfaces are just easier to keep clean than surfaces like wood or paper. However some metals, like copper and zinc form a fungicide when they oxidize. That is why better asphalt shingles are made with zinc granules in with the stone granules to prevent the fungus streaks you often see on roofs in the South. Copper or zinc ridge strips were often used for this purpose, too. But metal duct systems can be easily cleaned and disinfected.
7. Mold can germinate, or “bloom” in as little as twelve hours and start to grow in a day or two. So weekly monitoring is essentially useless. If the moisture is too high, mold will get ahead of you really fast.
8. There are tons of alarmist stories and law suits out there right now so it’s about impossible to sort out the truth. That’s because no one seems to really know the truth.
9. Lawsuits regarding mold almost always point to the builder unless there is some demonstrated neglect by the owners, such as allowing a leak to go unfixed. However, improper detailing can leave architects and engineers with a legal exposure, too. No matter the situation, it is very hard to determine fault with any accuracy since there are many sources of moisture entering a house and because of the lack of scientific data, the damage due to mold is hard to quantify. Still, many of the judgments awarded in mold lawsuits are based on sympathy for the homeowner and not actual facts like many fantastic lawsuits these days.
10. The longer a house is under construction prior to the roof going on and getting the house “dried in”, the more susceptible it will be to mold. Work should proceed expeditiously to let the house get dry as quickly as possible.
11. The greatest risk of mold growth actually occurs during the cooler months when the relative humidity remains above 90% for sustained periods. That would be a day like we had on Wednesday when everything seems to have condensation on it. I know it seems counter-intuitive, but during the high humidity, hot days in the summer, the relative humidity is actually lower than those damp days in the winter. This is because warm air can hold more grains of moisture and the surfaces are warmer and the dewpoint is not reached to cause condensation. Cooler surfaces cause condensation, not warmer ones.
12. The New York City Department of Health and Mental Hygiene Guidelines on Assessment and Remediation of Fungi in Indoor Environments (2002) is the most widely recognized guide for remediation.
13. One interesting thing I have learned is that mold will not grow on lumber with a moisture content below 20%. And even then, the wood must remain sufficiently wet for approximately seven days.
14. Your yard (and mine) is loaded with mold. Everyone’s is except maybe in Arizona. Even there the spores probably exist, just waiting for a little moisture.

The bottom line is this. Your builder should warrant the health of the house he is turning over to you. However, I don’t know that there is any way he can really certify this since there is no “standard” in the industry. So a measure of reasonableness is required. The mere presence of mold is not a cause for alarm. But a large and visible outbreak of mold needs to be dealt with in a level-headed way. A well-educated builder is the first step in preventing mold. Controlling moisture is the primary mission. If you do that, you will control mold in your house.

If you want another perspective on the validity of the mold health issue, you might find this article, The Mold Scare: Medical facts versus dubious myths, by Gailen D. Marshall Jr., the director of the Allergy & Clinical Immunology Division at The University of Texas Medical School-Houston interesting and enlightening.

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If you would like to read more articles about house and home design, please visit my other website, www.about-home-design.com.

All architecture is shelter, all great architecture is the design of space that contains, cuddles, exalts, or stimulates the persons in that space.”-Philip Johnson     

    If you asked me to give you a short answer to the question, “What will make a house be my perfect house?” I would have to say this: Everything should just seem to be in the right place. Unfortunately, the word “seem” is pretty vague. So it follows that the characteristics that will create Your Perfect House are subjective, and the concepts are sometimes difficult to grasp. These are the immeasurable, unquantifiable aspects of architectural design.

    These issues relate to emotions and to other sorts of perceptions that can’t be described in feet and inches. It’s a little difficult to get your arms around the concepts we’re going to talk about, which may be the reason many books about designing homes do not even attempt to discuss them. But they are vital for you to be aware of so you can be a full partner with your architect in the design of Your Perfect House. I’ll elaborate upon them in future posts. But for now, here are a few key concepts that take a house beyond simple shelter and elevate it to the status of “home.” 

A Home Needs Sequential Progressions-Our Minds Seek Order

    We don’t like to go from silence directly to eardrum-shattering noise. We can’t stand turning on a bright light when our eyes have adjusted to the darkness. There has to be a gradual transition, a segue from one thing to another. It’s the same when we enter a house. We are most comfortable if the journey from the public spaces outside the front door progresses through a thoughtfully designed sequence of increasingly more private spaces, eventually ending at the most private spaces.  

Don’t Design a Building, Design Spaces

    Architects don’t simply design houses. We design spaces. The house is merely the enclosure and definition of those spaces, both inside and outside the house. We think in terms of spaces more than objects.

    When architects design houses, they are actually creating spaces within those houses that will work for the people who will be living in them. This is what a good architect is trained to understand. This is what he should have a sixth sense about. What will the spaces feel like? What size is right? What shape and character is best?

 Control the Scale-Keep It Human

    A room is a stage for human activity. Rooms become important because of what happens within their boundaries. Because the rooms in a house are meant to contain human activities, they should necessarily be sized to match the intended use and therefore always maintain a human scale.

    Architects always want to create spaces that match the function for the users. Let’s say that Joe down the street has a dining room that’s 14 by 16 feet. Fred wants to build a house that will be “even better” than Joe’s. Fred might say, “Hey, I don’t have to have a 14-by-16-foot dining room. I can afford a room that’s 20 by 24.” After all, isn’t bigger better? Not always, I say. An architect can help you discover the proper size and proportion a room should have to suit the function and the particular users of that room, just the same way a suit of clothes should fit the wearer perfectly or the clothing will feel awkward and wrong.

    Making a house a home is a matter of designing the spaces we live in and not simply erecting a building that will keep the water out and the heat inside. It’s about understanding scale, transitions, progressions, order, and aesthetics.

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If you would like to read more articles about house and home design, please visit my other website, www.about-home-design.com.