How Crawl Spaces Affect Your Home Air Quality

Your Crawlspace Could be Contaminating Your Indoor Air


Have you ever heard of the Stack Effect? The Stack Effect is when water and excess moisture build up within your crawl space creating high levels of humidity. As the air warms, water vapor is pulled up from your crawl space through the foundation of your home (subflooring and flooring) causing all that air that was once beneath you, to linger within your homes living areas. Because humidity from your crawl space passes upwards towards the drier air of your home, the elevated humidity levels can contribute to higher heating and cooling costs and negatively affect your homes value. As much as 50% of the air you breathe inside your home can come from your crawl space.

In warmer months, warm and moist outside air enters your crawl space, condensing on cooler crawl space surfaces creating an ideal environment for the growth of mold, allergens and dust mites. Excess moisture also contributes to wood rot over time. Damp wood attracts insects like termites and carpenter ants whose colonies further damage the integrity of your homes wood structures. Fiberglass insulation easily absorbs moisture which causes it to sag and fall onto your crawl space floor. Cold weather months bring in additional problems as your homes floors rely on insulation to keep it warm, but insulation has fallen out of place due to high moisture content leaving your home with a higher heating bill. Unpleasant smells, mold, condensation on walls and ceilings, insect invasions and unexpected allergy like symptoms can all be signs that your homes air quality has been affected due to an under maintenanced crawl space.

Not only can there be damage to your home but your family and pets health can be at risk as well. According to the EPA, dust mites are the leading cause of indoor asthma attacks. Because dust mites thrive in humid environments, crawl spaces become an attractive breeding ground placing homes at risk. When mold grows it releases mycotoxins which can seep through the floorboards of your home causing sickness and can be difficult to treat as mold spores travel through air populating anywhere there is moisture. Sub flooring can become warped due to moisture accumulation and your homes structural integrity can be compromised when exposed to consistent high moisture levels, condensation and humidity which is why it is important to treat your crawl space as you would any other living space in your home.

When thinking about your crawl space here are some tips to help keep it dry and improve your homes air quality

Keep Moisture Out

Moisture control is one of the first steps towards having a safe and clean crawl space. Moisture should ideally evaporate back into the atmosphere. Problems occur when moisture condensation sits around wood where mold and mildew can grow. When left alone, your homes integrity can be compromised. Making sure that outside water sources are being directed away from your home, like your gutter system, can help keep water and moisture from entering your crawl space. Raising soil levels where water can drain away from your home is also a good idea.

Inspect and Clean the Interior of Your Crawl Space

Once you’ve eliminated all external sources of moisture, you can begin to inspect and clean the crawl space itself. If you have exposed dirt floors, you should consider sealing it with a moisture retardant. Dirt floors naturally retain moisture which can be pulled up into the air from the floors above. Dirt is also an entry for insects and rodents as they dig their way through soil. Regular cleaning can help keep your crawl space clean and moisture free. If your crawl space has already been affected with things like standing water and/or mold growth it may be necessary to call a professional.

Keep Out Rodents and Ventilate

Once your crawl space is cleaned you can check for any entry points that rodents may have access to and block them off. Keep in mind that even small cracks and seems can be entryways for rodents to travel through. It’s still important to allow your crawl space to ventilate. Water vapor barriers are an excellent solution for allowing crawl spaces to vent but still keeping pests and unwanted visitors out.

Insulate the Crawl Space

After vents and vapor barrier are put into place insulation can be installed. Fiberglass batts are the most common and popular insulating solution for crawl spaces and can be installed between floor joists. While effective, pairing fiberglass batts with spray foam insulation creates a super tight seal against heat transfer and air movement through your homes first level of flooring, making it a more efficient solution. A thin layer of spray foam can be enough to fill in the nooks and crannies of your crawl space, helping to keep warm air in and cold air out. Spray foam is also great because it is impermeable to moisture so mold and mildew can’t grow.

Interested in learning more about crawl space cleaning or repair in the Portland/Vancouver metro area?

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