This is my first post so bear with me. I have a home @ 40 years old with a rough sawn cedar siding exterior that is stained a light tan color. There is an excessive amount of what appears to be mold on the siding – I assume it is mold because it washes away witha mixture of bleech and water. There is some mold on the inside of the house in damp areas – bathroom showers etc. I have read several articles on mold and the effects it might have on my health but most authors define mold as good/bad and it is the black mold that is a risk. How do I know the difference, what do I do to contain the mold or get rid of it fo good and most important is my bleech solution effective?
Thanks
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The health effects of mold are typically limited to allergic reaction (similar to hay fever), although mold can also trigger asthma attacks in sensitive individuals. "Black mold" does not really describe a species of mold, since many different molds are black. In popular use, "black mold" usually refers to Stachybotris chartarum, a species of mold that a couple of limited studies indicated may have been the cause of some serious health effects. Most public health authorities do not consider molds found in homes in the US to be a risk except for people with compromised immune systems. For more on the health effects, go to http://www.cdc.gov and search for "mold".
On the other hand, mold growth indicates moisture problems that need to be addressed to prevent structural damage and molds can also damage the structure directly, so anytime that you have mold you need to get rid of it. Bleach works well to get rid of what is currently growing, but it is only a temporary fix. You have to prevent the mold from recurring. That means eliminating the source of moisture that is necessary for mold to grow. In the bathroom and kitchen, use an adequate exhaust fan to vent moisture in the air to the outside of the house. You can have a timer installe on the bathroom fan to ensure that the fan runs long enough after a shower (which is usually what generates most of the airborne moisture) to adequately exhaust the water vapor. Check for leaks in the envelope of the house (roof, walls, etc) and correct any that you find. If you have a crawl space make sure that the it is adequately sealed/vented. You might want to use a paint that is formulated to prevent mold on the surface of the paint--Zinsser makes one, but I can't remember the name at the moment. You do have to get rid of any mold growing on the surface before you paint, though. You can find additional information on mold control at http://www.buildingscience.com.
Finally, testing is not recommended by most authorities--except for those that make money from providing testing. That is because if you test for mold in the air, you will almost certainly find it. There are no standards for what is an acceptable level of airborne mold in the air. The main thing that air testing can tell you is whether you have more mold in the indoor air than is in the outdoor air at the time the samples were collected. If you have more in the indoor air, then you have a problem that needs to be corrected by addressing moisture issues.
Thanks for the message. Just one additional fact that may/may not make a difference. My shower door is caulked in clear caulk. The mold is "inside" of the caulk so that I cannot clean without removing caulk. Is this an indication of internal mositure probelms? MikeC
"Inside the caulk" can mean several things. The clear caulk may be laid on top of live mold, which keeps growing. Or the mold may be eating the caulk itself. Either way the caulk will have to come off to treat the problem.Air movement is essential to keep mold at bay in bathrooms. Even humid air that is circulating resists the formation of mold on surfaces better than stagnant air. Shower doors should be left open between uses if at all possible.Bill
I concur with Bill Brennan.
While every thing Jim has wwritten is excellent advice, I can't help but wonder whether all you have is simple mildew growth on surfaces. It is common and fits your description
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Exactly what I was thinking.
You are correct, this may be mildew.
On the other hand, in generic terms, mildew is essentially mold that occurs on the surface of a substrate and doesn't invade the substrate. I'm definitely not a mycologist, so that's most likely an over-simplification.
In terms of control, it's a matter of degree. That is, if it's only growing on the surface, then it is most likely supported by moisture in the air (humidity) and will usually be easier to get rid of and prevent.
What JimB said, although also use the forum search feature - we just had a discussion on bleach for cleanup and I linked a number of differing views on se of bleach.
BTW, "mildew" and "mold" are essentially synonymous.
Back in my landscape construction days I would often see homes with mold growing on the outside of the home. Often it was because large trees or shrubs were growing close enough to the home such that areas were getting very restricted sunlight, and/or very restricted areas of airflow alongside the house. As has already been stated by others, you need to deal with what is creating the environment for the mold. For the inside of your home other have given you some suggestions, and as for the outside try to clear away anything that is creating permanent shade ( unless of course it is your neighbours house ). If it is not possible to eliminate the source, you may have to set up a regular schedule of cleaning often enough that the mold never really has a chance to get fully established again.
When we bought our cottage our shower unit had the same type of mold you described which was under the clear silicone caulking. I removed all the caulking, cleaned well with bleach, and re-caulked. It is several years later and I have not seen any recurrance of the mold in our bathroom, but we also always use an exhaust fan during and after showers.