How Crawl Space Moisture Impacts Your Living Space

What Causes Moisture in Your Crawl Space?

Moisture and condensation occur in the crawl space when hot humid outside air moves through your crawl space vents and meets the cooler air under your home. The change in temperature alters how much moisture the air can hold and results in condensation. Think about putting a glass of iced tea outside in the summer. The hot air meets the cool surface of the glass, giving up the moisture the air is holding and causing “sweat” on your glass.

 

Water or moisture in the Earth’s soil and water infiltration from rainstorms can also contribute to the high moisture and humidity levels in the crawl space. The Earth under your home is full of moisture, even if you don’t see it, it’s there. Take a few spoons full of soil from under your home and put it in a zip lock bag. Soon, you’ll see condensation on the bag. Water infiltration from storms can be caused by clogging, overflowing gutters, oversaturated soil, or poor grading around the home’s foundation.

 

Why is Condensation in the Crawl Space a Problem?

An excess of humidity and moisture in your crawl space, especially over long periods of time, can result in mold growth on the floor's joists and paper backing of fiberglass insulation. In extreme cases, homeowners may even experience wood rot.

 

Mold and mildew need 3 things to grow and thrive.

1.       Warm temperatures

2.       Organic food source

3.       Relative humidity over 60%

 

For wood rot to occur, the wood moisture content needs to be about 19% or higher for a prolonged period. This high moisture content causes the floor joists and sub floor to soften and splinter.

The moisture in the crawl space is absorbed by the wood substructure (floor joists and sub floor), and by fiberglass insulation. This moisture adds weight to the insulation causing it to fall away from the floors, rendering it useless.

 

How does this impact your living space?

Approximately 50% of the air in your home comes from the crawl space. This is a result of the stack effect. Inside your home, you may notice musty odors, high humidity, irritations to asthma or allergies, and damage to wood floors or uneven floors.

 

This is because all the allergens, moisture, dirt, and odors from your crawl space are being pulled up into your home, impacting the air quality. It can cause dust mites, excessive dust in your home, and sometimes homeowners may notice mold growth in the living space.

If your ductwork is in your crawl space, gaps in the duct system can pull in dust, dirt, and allergens. Inside the home, you might notice excessive dust or dirt around air registers and sometimes even condensation on the vents.

 

When it comes to your floors, humidity can cause buckling, cupping, or bowing of wood floors as the material shrinks and swells due to fluctuating moisture levels. Soft or bouncy floors can be a result of settlement or soft floor joists and sub floor.

 

How Is Moisture in the Crawl Space Mitigated?

To control the moisture and humidity in the crawl space, we find that a crawl space encapsulation is the appropriate solution. When encapsulating a crawl space, we follow the following steps:

 

1.       Clean out all debris, fallen insulation, and damaged vapor barrier.

2.       Remediate mold and mildew with an antimicrobial.

3.       Control ground water/ water infiltration (where necessary)

4.       Install and seal a durable vapor barrier.

5.       Seal all vents and penetrations to the outside including the rim band and sill plate.

6.       Insulate the foundation walls.

7.       Install a dehumidifier to control relative humidity.

 

This is the preferred solution to managing crawl space moisture and humidity because it allows us to control the environment. We can’t change the hot humid weather, but we can keep the outside from influencing and impacting the crawl space environment.

 

The crawl space will still experience temperature and humidity fluctuations as we go through season changes and wet and dry seasons. This is where the insulation and dehumidifier come in. We can help control the now isolated environment much like your wall insulation and HVAC system control the environment in your home. The dehumidifier is set to turn on when the relative humidity in your crawl space exceeds 55%. It will pull the moisture from the air and circulate dry air throughout the crawl space.

 

What Do I Do If I Think There Is a Moisture Problem in My Crawl Space?

If you think you may have a moisture or humidity problem in your crawl space, contact a company that specializes in crawl space repair. Have a professional evaluate the space, take photos, moisture readings, and measure the wood moisture content of your joists. Ask them to take photos of these readings on the meter too. Don’t be afraid to join your inspector in the crawl space for the inspection if you’re capable and willing.

 

For a free crawl space inspection call The Drying Company at 1-757-566-8622 or 1-757-566-8622. Our Advisors will walk you through their findings, answer all your questions, and leave you with everything you need to make an informed decision for you and your home.