Your Crawl Space!

Have you ever been in your crawl space? Is it a clean place? Is your HVAC (heating and air) system located there? Does your crawl space have an adequate vapor barrier? Is there ventilation down there? These are all important questions which must be part of a crawl space evaluation! Here’s why. The crawl space doesn’t have any sunlight (UV) light to kill bacteria and/or mold spores. The temperature zone which mold lives is similar to the temperatures humans live in, and, when the moisture content rises above 60% relative humidity, there’s enough moisture in the air for mold to grow. The crawl space, or underside of your home is made up of organic material (wood), and this is food for mold. Importantly, mold is everywhere, even in the air you breathe outside, but when it (mold) has proper conditions, it will grow and colonize in very large numbers, and for a contained environment (your house or crawl space) that is not a good thing. This is what proper mold remediation is all about. Proper mold remediation is the removal of excessive mold spores, bringing the property back to normal levels. This is not properly done by sealing the mold under paint, etc., but by removing it from the property through sanding, wire brushing, or soda blasting type methods!

Does the underside of your home ever reach over 60% relative humidity? Yes! If there are vents to the outside from your crawl space, then the outside relative humidity will also be the humidity level in your crawl space. When it rains outside, sometimes for weeks on end, you have optimal conditions under your home for mold growth. If you ever have standing water or flooding where standing water gets into your crawl space, this is a recipe for a sick house! Let me quickly point out that if you have standing water the problem is compounded because it is not clean water. Ground water is not considered clean water, and after setting under your home for several days, it is to be considered black water. This is highly contaminated water. If your crawl space has these type of frequent conditions, whether flooding or just vented air during the rainy season, over many years, what do you think will happen? That’s right. You can now begin to see how your crawl space can easily be mold contaminated. I have been told the air in the crawl space updrafts into the house, so it’s easy to see how this can adversely affect the air you breath in your own home!

Now let’s address your HVAC system which is located in your crawl space. Do you think an HVAC system is perfectly sealed? If you paid extra for this it may be. If your crawl space develops a mold problem, there is opportunity for the contamination to be spread throughout your home. Now, if your crawl space is a “clean space”, then there is nothing to worry about. I’ll explain what I mean by a clean space in a minute. For the HVAC in the crawl space, when the blower kicks on to push the warm or cool air through the ductwork to the house, there a of couple of things which can draw crawl space air into the system. One would be a dirty air filter, which could restrict the air flow to the blower box. The blower still needs the air to push through the system, and if it can’t get all it needs through the filter, then the vacuum it creates will draw air from a deficiency in the box (a crack or loose fitting). Another potential way for crawl space air to enter the system is just improper or poorly design. Yes, this can happen. Home builders many times go with the lowest bid from contractors to keep the price of the home down, and sometimes you get poor workmanship or inferior design. Possibly flex duct instead of hard pipe is one example. Flex will deteriorate and need replaced over time because of holes or tears, etc.

What is a clean space for your crawl space? A clean space is a crawl space which has a proper vapor barrier. A seamless vapor barrier, seamed with adhesives is the best! The vapor barrier should also go up the side wall to the base plate (bottom of exterior side wall). This will seal the vents to the outside (unless the homeowner desires they be left in), and also prevent moisture from seeping through cinder block foundation wall construction. A crawl space dehumidifier which has an automatic pump and thermostat, and shuts down when there are below freezing temperatures, is ideal. A utility fan on a timer will help to circulate the air, and the dehumidifier to control the humidity, will go a long way in preventing any further issues by controlling the environment. The crawl space can only be a clean space with these appliances and vapor barrier if it is free of contaminants like mold. Some crawl spaces have water drainage issues, and also require a sump pump be installed along with the other items.

Crawl space remediation should be a one time deal. If properly done (we soda blast clean the underside of the house), then the environment should be such that the conditions which allow mold or bacteria to grow are not present! Period.