I've written articles on indoor air quality and mold remediation for quite a while now and realized a basic primer for homeowners with the facts about mold and mold remediation would be appropriate. Mold has been around since the beginning of time, but in the news for only a couple of decades. It was a landmark case where Linda Ballard won a lawsuit against her insurance company that really brought it to the public's attention.
The health sciences professionals have gone back and forth for years debating the health effects of mold exposure to humans. There has been much progress made the last five years with opinions coalescing from the experts that mold has the potential to affect one's health. The US Centers for Disease Control and Prevention (CDC), the Institute of Medicine of the US National Academy of Sciences, the World Health Organization, and other prominent organizations all agree that living or working in a building with mold damage results in increased risk of respiratory disease. Statistics on exposure are available in Europe; here in the US there are no State or Federal TLV (threshold limit values) or TWA (time weighted averages) for exposure to mold, unlike what we have for chemical exposure. This is primarily due to the fact that one person's response to mold exposure can be different to someone else's.
There are some guidance documents on mold investigation and mold remediation in print, but there are no laws on the books. A couple of states have attempted legislation to control the industry with disastrous effects. What we're left with is an industry that is self-governed. There are standards such as the IICRCS520 for mold remediation and the S500 for water damage that experienced professionals utilize. There are industry organizations like the Indoor Air Quality Association (www.IAQA.org) and RIA (www.restorationindustry.org) that promote professionalism and ethics. As the Philadelphia Chapter President for IAQA I run workshops to educated and further the need to operate in an ethical manner in order to serve the needs of our clients (you, the public). As always it's "buyer beware". I find that the real professionals are the ones who attend our workshops and the ones who give the industry a black eye are no shows.
What is Mold? The colloquial term mold (or mould) is applied to a large and taxonomically diverse number of fungal species Molds (and mildew) are fungi. Fungi are not part of the plant or animal kingdom, but have their own kingdom. The fungi kingdom includes such wonderful organisms as the delicious edible mushrooms some of us enjoy, the makers of the "miracle drug" penicillin and the yeast that makes our bread rise and our fine wines ferment. There are also fungi that spoil our bread, our fruit, cheese and sometimes our crops. Biologically, all fungi have defined cell walls, lack chlorophyll and reproduce by means of spores. Approximately 100,000 species of fungi have been identified and can be just about any color. The vast majority of fungi feed on dead or decaying organic matter - they are one of the principle agents responsible for the natural recycling of dead plant and animal life. Different mold species proliferate depending upon the "AW" (water activity) with some species that require very wet while others just damp conditions.
How does Mold become a problem inside a structure?
As mold spores digest dead organic materials as their role in the ecosystem has been defined. They are the ultimate recyclers. As they break down organic materials they release spores into the air (sporulating). This is a reproductive activity similar to seed dispersal from plants. Ranging in size from about 1 - 20 microns they are easily carried by air currents inside every time you open a window or a door. We carry them in on our shoes and clothes. Mold growth occurs inside when mold spores land on a surface with enough moisture to support their growth. Common sources of excessive indoor moisture that can lead to mold growth and create the need for mold remediation include:
• Flooding from ground water
• Plumbing leaks, sewer back-ups or overflows
• Elevated relative humidity, especially in basements & crawl spaces
• Roof leaks from missing or improperly installed elements
• Window leaks resulting from improper flashing or wind driven rain
• Ice damming (covered in a prior blog article)
• Condensation when surfaces reach their dew point
How do I prevent mold growth?
The easy answer to prevent and halt microbial growth is to control what it needs to thrive - moisture.
1. You have to address any obvious water penetrating your structure.
• If ground water is a problem then keeping your gutters and downspouts clean and clear is a first step. Inspect your property during a rainstorm, taking note where water pools around your foundation.
• Your grading needs to have a positive pitch away from the foundation.
• Vegetation should not be too close; it should be 2 - 3 feet away from foundation.
• Go into your attic and check for leaks during a rain event especially checking around boots where there are penetrations through the roof.
• Check for proper ventilation in attic. Also covered in another blog article
2. Buildings must be conditioned.
• You have to monitor the relative humidity and control it with dehumidification. ASHRAE recommends keeping relative humidity between 30 - 60% to prevent mold growth. We know that there are drought tolerant species that will proliferate between 50 - 60% therefore we advocate keeping relative humidity under 50% to prevent the need for mold remediation.
• Insulation is another consideration, but one that requires extensive explanation and delves more into the building sciences then the average property owner wants to get into to. For more information please check my blog for information on how lack of insulation can create condensation that leads to mold growth.
3. Exhausting excess relative humidity from bathrooms and kitchens can and often is another major fault in design.
• Bathrooms must have exhaust fans. These fans must exhaust through the roof and not into the attic or the soffit vents.
• Clothes dryers need to be vented outside. It's important to insure that the vent is cleaned and checked on a regular basis.
• Line drying of clothes needs to be employed only when an understanding of relative humidity and monitoring of such is considered.
4. Wall coverings on exterior walls can be problematic.
• Vinyl wallpaper on exterior walls act as a vapor and do not allow the structure to breathe, this can create condensation issues that allow for mold to grow.
• Vapor barriers (anything that has an extremely low permeability factor). Contrary to some thinking and some TV home improvement shows, there is no place for vapor barriers anywhere in a building in our region.
5. What do I do to prevent mold growth once I've experienced a water incident?
• If you have a flood or plumbing issue, getting the standing water up quickly and drying out the structure is key. If you can get it completely dry within forty-eight hours you can prevent mold growth and hence the lack of need for mold inspection, mold testing and consequently mold remediation.
If you're unable to clean up and dry out the structure within the critical forty-eight hour window to prevent mold growth then consult with a certified mold remediation contractor or an environmental consultant.
Craig Camel is an environmental consultant and building science professional. Owner of http://www.advancedmolddiagnostics.com an successful consulting firm in Delaware County, Pennslyvania. Thirty yrs experience in indoor air quality investigations with mold and mold removal qualifies him as being experienced. http://www.advancedmolddog.com/iaq_investigations.php
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