About House Mold
There are currently about 1.5 million species of fungi known to man under the 1000 fungal genomes project. This represents one of the largest branches of the tree of life. Recent studies also show that the arrival of fungal organisms took place around 1 billion years ago. They were the first few living inhabitants on Earth. They have learned to adapt to many climate changes and have survived many catastrophic events throughout Earth's history.
The purpose of mold.
Even though they have a bad reputation with most humans mold is necessary for our survival. If these simple organisms didn't exist, the dead organic materials left behind by falling leaves and trees would litter our environment forever. We would also have to share our space with the remains of all other dead organic matter (ie. animals). This would be quite a different world without fungi. Realize, they are required for our existence; capable of biodegrading any naturally occurring substance and many man made ones.
You see, the purpose of fungi is exactly that; to break down and decompose organic matter. Organic matter comes from something that was once living. A few common examples are: wood, paper, glue, food, soap, leather and even the oily residue from our fingertips. They feed on organic matter and have an appetite that is nearly impossible to stop.
There are four things that fungi, aka. 'mold' require to stay alive:
Organic matter: This one should be obvious by now... Organic matter is the food for mold growth. The purpose for its existence. Since we can not possibly remove organic material around us, this is irrelevant.
Mold spores: This is how they reproduce and spread. Unless a serious problem already exists, controlling the amount of mold spores in our homes won't help much. The mold spore count will always be very similar to the air outside of the house. Air filters will help but even the cleanest indoor air will have mold spores.
Temperature: Unfortunately for humans, mold thrives in an environment similar to that which we also consider comfortable. Changing the temperature in your house is really not much of an option .
Moisture: This is really the only thing that can be controlled inside of our homes. High moisture levels provide a perfect breeding ground for mold. It is important to note that building materials do not necessarily have to be soaked to be targets for mold growth. Relative Humidity is an important factor also.
Since moisture is the only requirement that we can control, we will start here. Luckily for us, unlike temperature, mold prefers much higher humidity levels than humans do. We are generally comfortable when the relative humidity is anywhere between 30% and 70%. Mold, on the other hand, almost 'requires' relative humidity levels of at least 70% for a significant amount of growth. It will grow in humidity levels lower than that but will do so more slowly. With that in mind, realize that before you attempt to treat your mold problem, you must first treat your moisture problem.
Keeping mold growth under control in your home
Fix plumbing leaks immediately: Constant slow leaks in the plumbing system of the house will keep humidity in these areas high for long periods of time. This is the perfect breeding ground for mold. Identify plumbing leaks and correct them as soon as possible.
Air circulation is important: Common activities such as cooking, bathing and doing laundry introduce moisture into the home every day. Proper ventilation removes these sources of humidity by letting them exit the house.
Keep things dry: Maintaining low moisture levels will prevent mold growth. Standing water in kitchens and bathrooms not only keeps those surfaces damp enough for mold growth, it eventually evaporates and puts moisture into the air. Don't leave wet towels or clothes lying around.
Properly graded soil: When water collects against your home, sooner or later it will seep into the basement or foundation introducing moisture into the building. Maintaining the proper pitch will prevent ground water from seeping in.
Building envelope maintenance: Leaky roofs and windows, clogged gutters, poor caulking all introduce water into the building envelope that protects you from the weather. Allowing this type of excess moisture into the house will allow mold to grow inside the home. Clean gutters regularly, check the roof for leaks and maintain the caulking around windows and doors.
Use dehumidifiers: Maintaining moisture levels in the home at 30-50% will reduce the possibility of mold growth to a minimum. 70% is the threshold for house mold primary colonizers like Alternaria, Aspergillus and Penicillium.
Identify areas that stay cool: Cool air can retain less moisture than warm air. As the moist air cools, the relative humidity rises towards 100%. When that happens, it condenses into liquid water. This is known as the "first condensing surface". Identifying these areas and keeping them dry will prevent a future mold problem.
If you have a problem with mold in your home, removing significant mold growth should be done immediately. Hire a qualified professional if you're not comfortable doing it alone!
Fun Fact: Did you know that the average person EXHALES between 1 and 2 liters of water a day?