All About Mold Problems in Houses
Decker Home ServicesBy William Decker, CMI
Mold problems (uncontrolled fungal growth) are increasing in houses. National TV programs have covered this issues in great detail, although they get many of the details wrong. This is, mostly, the result of "tighter" buildings (better insulated and sealed), newer and less expensive building materials and recent design trends like finished basements and attic areas that are not properly constructed to properly manage water and moisture. While mold is a serious problem, it is easily manageable and avoidable.
First thing to remember: Mold is NOT a problem, mold is a SYMPTOM of a problem. The actual problem that causes the mold growth is water intrusion. If you remediate the mold, but do not fix the CAUSE of the mold growth (i.e., water intrusion or moisture problems) the mold will come back and you will have wasted a lot of time and money. Hiring a professional Home Inspector who is trained in thermal imaging and has specific experience with water and mold problems and will help to solve the actual causes of the problem and not just gloss over the results.
When dealing with mold, the simple equation to remember is WATER + FOOD + TIME = MOLD GROWTH. Fix the cause of the water problems and eliminate any one of these factors and the mold growth problem is solved. To understand this, let's look at each one of these variables.
Water: Water can enter a house in many ways, and it
will do so in all possible ways. People are mainly concerned with
water entering their house through a leaking roof. While this does happen,
it is much more common to have ceiling water leaks caused by bad attic
ventilation, condensation problems and improper attic insulation and ventilation.
Water can also enter a house through badly installed windows and doors, plumbing
leaks and badly flashed masonry copings. Remember that water has three
forms, liquid, solid and vapor. Ice dams caused by non-professional attic
insulation and ventilation can cause water problems when it finally melts.
Snow can blow into an attic through roof and gable vents that are not
professionally installed. High indoor humidity levels, and the commonly
seen the 90+ % humidity levels in our area
(Chicago), are enough to promote mold growth.
The most common concern is water intrusion into basements. Remember, basements are really just big holes in the ground. All basements are moist and with the modern trend towards having a "finished" basement, mold has more places it can grow than ever before. Basements should be equipped with de-humidifier units and these should be run during the warm months to keep basement humidity levels low. It does not take a couple of feet of standing water in a basement to cause a mold problem. Most basements do not "flood" but have minor seepage problems, as in small amounts of water dripping through minor foundation cracks and wall penetrations. I have seen many new, but foreclosed, houses that have no plumbing leaks or roof problems that turn into "mold farms" simply because the outdoor humidity changes and the lack of "conditioning" of the inside air.
Food: Like all living things, mold needs food to grow. The most common food for mold is cellulose. Most of the new building materials are made of cellulose. Wood is just densely packed cellulose. Drywall is covered with paper which is made from recycled newspaper which is just ground up cellulose. Even the preferred, "green" blown-in insulation is just ground up cellulose. One of the largest sources of indoor cellulose is the lint that comes out of your clothes dryer if it is not properly vented and regularly cleaned. We do not see many mold problems in older houses with plaster walls because plaster is not made of cellulose and does not provide food for the mold. Many times, older houses that have never had any problems with mold, when they undergo remodeling, develop mold issues because the older plaster has been replaced with cellulose faced drywall. It seems like mold had sources of food everywhere in your house.
Time: Put water and cellulose together and add some mold spores (the "seeds"
that mold grows from) and give it some time, and you will have mold
growth. Mold spores are everywhere because mold is a natural part of the
environment. The key is to not give the mold spores time to grow and rise
to harmful levels. If
you experience a water problem in your house, the likelihood of developing a
mold problem is directly related to how quickly you dry out the affected
building materials.
Mold Types: There are thousands of types of mold. Mushrooms are fungi, just like mold. Cheese is formed through mold growth on milk. Buying fresh, "organic" vegitables and bring them into the house without cleaning them will introduce foreign mold spores. If you have a lot of house plants, the number of mold spores in the air of your house is increased because many molds grow on plants.
Most types of mold are harmless to humans and cause no problems. One commonly seen mold genus is common mildew, which we all see if we don't regularly clean our shower tiles. Cladosporium is a common, but harmless, mold that causes wood to rot and is necessary (otherwise all dead trees would just sit around taking up space). All these molds are harmless and occur naturally in outside air.
But is your house has moist cellulose sitting around, some uncommon mold types will start growing to greater than normal levels. Penicillium, the mold from which we get the antibiotic Penicillin, is a commonly seen household mold whose spores can cause allergic reactions in some people. Aspergillus Niger is another commonly seen household mold that also affects some people, causing symptoms similar to the flu. Because Aspergillus appears black in color, it is commonly mistaken for "Toxic Black Mold".
The real "Toxic Black Mold" is called Stachybotrys Chartarum. Stachybotrys is especially dangerous not because of allergic reactions, but because it also produces mycotoxins, which many people react to as they would to nerve gas. While very harmful, and even deadly, Stachybotrys is not very common and is usually seen only in houses that have experienced long term water damage.
How do you know if you have mold? If you see discoloration on walls or
baseboard near the floor, especially in basement areas or in the corners of
exterior wall closets, this could be mold. Look for areas of discoloration
starting in circular forms (mold colonies) what spread outward and appear to
wick upward (following the water). If you see surface mold, there is no
real reason to have the mold tested. All harmful home mold growth should
be professionally remediated regardless of the type of mold. If you are experiencing flu or cold like
symptoms (runny nose, persistent cough, watery eyes, asthma like symptoms, etc)
but do not see any signs of surface mold, there could be mold
growing, unseen, behind your walls or in the unseen attic and basement areas. If no visible
mold is seen, mold testing using air samples can be done which will determine if
the mold spore levels in the air is excessive. Hire a certified
(specially trained and tested) mold sampling professional like a Home Inspector
or an Industrial Hygienist.
SPECIAL NOTE: Many people are under the misconception that mold can be washed away using bleach. BLEACH IS COMPLETELY CONTRAINDICATED FOR MOLD REMEDIATION! While used for non-porous materials, like tile, using common household bleach to clean mold off of porous materials (drywall, wood, paint, etc) will make the mold growth worse. When the bleach breaks down the remaining chemicals actually serve as a sort of fertilizer for mold, making the growth come back faster and larger. The type of chlorine based mold remediation products used for large scale, industrial, mold remediation have a much higher concentration of chlorine that is available for safe use by the general public and will cause lung damage. Mold remediation is a process that should only be done by licensed, certified, specially trained and insured mold remediation professionals!
What to do if you have mold: Regardless of the type of mold, the process of mold remediation is the same. As previously stated, mold remediation is something that should that should only be done by specially trained professionals. I have seen many instances where people with mold problems try to remediate "on the cheap", with very bad results. Non-professional "mold contractors" wash the mold with a bleach solution, do not remove the affected building materials and in a matter of weeks, the mold is back, with a vengeance! Remember, you can spend the necessary money doing the remediation professionally up front, or YOU WILL be paying for it in the end, on a much bigger scale.
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| Interior wall corner. No visible problems. | Thermal imaging reveals water condensation behind wall. | Mold growth behind wallpaper. |
Remember, before the mold is remediated, the SOURCE of the water infiltration should be determined and fixed. If this is not done, the mold will return. A professional home inspector with specific experience in solving water intrusion problems should be consulted. Thermal imaging is an essential part of finding the cause of the water problem and fixing it before cleaning up the mold.
Professional mold remediation involves multiple stages:
1) The affected parts of the house should be isolated. This involves plastic partitions and negative pressure filtering machines to exhaust the spores outside the house. This also involves closing off all HVAC ductwork that serve these areas with all ducts, furnace and air conditioning machinery properly cleaned. Remediation workers will wear isolation suits and wear specially rated respiration devices.
2) Remove all the affected building materials. All drywall, non-structural wood members and insulation must be isolated (double plastic bagging) and removed from the house. Additionally, all clothing, furniture, carpeting and other household items should be removed and professionally cleaned by mold professionals.
3) Any non-removable building materials should be cleaned using specially designed vacuums and cleaning machines. All remaining areas should be remediated using one or more of the approved mold killing processes:
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Dry ice blasting |
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Fungicide |
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Ozone cleaning |
5) All affected areas should be encapsulated. This involves covering these areas with specially designed coating paints which include fungicide chemicals. Encapsulating the mold will stop its growth and seal it from releasing more spores.
6) The affected areas should be rebuilt, replacing the removed building materials with new wood, drywall and paint.
7) After the mold is professionally remediated, the affected areas should be re-tested, called clearance testing, using air sampling. This testing should be done by an independent mold testing professional or home inspector specifically experienced with mold clearance testing. The mold remediation company should not also do the clearance testing. This is a conflict of interest. If the clearance testing reveals that there are still excessive mold spore counts, the remediation contractor should be called back and further remediation done, at no additional cost! Make sure that any remediation contractor agreement includes further work if clearance testing shows more mold.
Mold is a problem, but properly addressed, both in the mold problem aftermath and in the initial cause, makes it a very manageable problem. Do-it-yourself fixes or trying to find the least expensive fix will only make the problem worse. Remember, you will never get more than you pay for and your house is an investment worth preserving.