Wet Crawl Spaces and Your Air Conditioner

Wet Crawl Space and Your Air conditioner

Summer is quickly approaching and you will be turning on your air conditioning very soon if you haven't already. We love our conditioned spaces but many people don't consider how conditioning the living space affects the crawl space. In fact, most people don't even consider the crawl space part of their home even though it has been proven the air in your crawl space is shared with your living space by up to 50%.

Crawl Space Mold and Soil Gases

If your crawl space is vented, like most are in America, the air inside the crawl space is affected by outside conditions like humidity, pollen and mold spores. When the crawl space takes on mold spores like stachybotrys or aspergillus, it can land on wood and other porous materials waiting for the right moisture levels to help it grow out of control. Wood rot fungus also likes to hang around until the right conditions are introduced. So what are the right conditions?

Mold Loves Moisture and Darkness

Crawl spaces are damp and dark so molds do very well in them. High humidity entering the vents in the foundation walls is a great way for mold to get a foothold on joists and sub-floors. Cardboard is another great food source and many homeowners like to store lawn mowers with grass clippings built up on the deck of the mower. Many harmful molds actually come from the soil so lawn mowers are great sources for toxic molds according to moldpedia.com. So what does this have to do with your home's air conditioning unit in the summer?

Does My A/C Unit Make My Crawl Space Damp?

I have had many conversations with homeowners that claim to never have a mold problem and then all of a sudden, bam! One reason is upgrading from a very inefficient heat and air unit to a very efficient one may be the cause of increased humidity in a vented crawl space. If you live in a home built 20 years ago and you go from a 10 to 20 year old HVAC unit to a 14 SEER system that blows cold air way more effectively than before, that cold air can affect the crawl space. We have seen homes where they upgraded the HVAC unit but not the ducts due to expense or maybe they were in good shape. Ducts installed 20 years ago have a different R value of insulation than today but even the R value installed today may not be effective at creating a thermal barrier between the warm summer crawl space air and the cold HVAC air. When a cold duct meets warm moist crawl space air, it’s like a cold glass of tea on a hot summer day. Sweating occurs on the ducts and that sweat evaporates and is absorbed by the surround insulation and wood.

Another reason we see crawl spaces explode with high humidity is if you take two identical homes and one home is kept on 74 degrees and the other is on 68 degrees, the home that is kept colder will condensate more in the crawl space if the HVAC ducts run through the crawl space. This is a shock to many homeowners. The best way to correct this is to install a dehumidifier to lower the dew point.

How To Stop The HVAC From Making Crawl Space Wet

The solution to fixing this problem is to control humidity which we would recommend a Hybrid Crawl Space Encapsulation System. Our solution does so much more than just control humidity. If you are looking for a worry free crawl space solution that addresses crawl space insulation, crawl space standing water, crawl space mold, crawl space humidity, crawl space vapor retarder and crawl space ventilation; ask about our proprietary Hybrid Crawl Space Encapsulation System.

About Michael Church

Michael Church has been involved with indoor air quality since 2005 and feels the unhealthy crawl space is one of the major problems causing poor indoor air quality.