5 Reasons Crawl Spaces Have Mold Problems

Many homes experience mold problems and homes with crawl spaces are more prone to mold when the crawl space is damp. In this article, I am going to talk about the top 5 issues that can cause mold to grow in the crawl space.

  1. High Outside Humidity
  2. Hot Crawl Space Cold Ducts
  3. Wet Floor Insulation
  4. Plumbing Leaks
  5. Foundation Flooding

High Outside Humidity

The air outside in most of the country is humid all year. Unless you live in a dry climate like Denver or San Diego. Humidity over 60% will affect your crawl space negatively. If you live in an area with high humidity you may consider crawl space encapsulation. Sealing the vents and installing a vapor barrier and dehumidifier will control crawl space humidity.

Hot Crawl Space with Cold Duct-Work

Condensation happens when hot air meets cold surfaces, the surface sweats and gives off moisture. The moisture enters the air and becomes high humidity. High humidity leads to mold. Control the dew point in the crawl space and you will control condensation.

image of ductwork sweating

Wet Floor Insulation

When your sub-floor insulation gets wet, it leaches water into the surrounding wood. Wet wood grows mold. Insulation can get wet from high humidity and plumbing leaks. Many times wet insulation should be removed and replaced while controlling humidity.

Plumbing Leaks Cause Mold

When you have a plumbing leak in the crawl space it can be hard to find. Most of the time the sub-floor insulation is trapping the moisture. Sub-floor insulation can also hide the leak for months or years. Wet sub-floors grow mold and in time will grow wood rot fungus. Check around toilet flanges for leaks with a moisture meter. Removing floor insulation and insulating foundation walls will make it easier to spot plumbing leaks.

Other articles of interest

Why Does Crawl Space Humidity Spike After Encapsulation

Is Spray Foam Good for My Crawl Space Floor

5 Problems to Fix in Your Crawl Space ASAP

Should I Remove Insulation from My Crawl Space

Crawl Space Foundation Walls Flood

Many contractors we come across tell homeowners that waterproofing the crawl space will control humidity and get rid of mold. Foundation flooding is certainly a cause of high humidity but not always the fix to high humidity. Also, removing humidity does not get rid of mold. If you suspect your crawl space is flooding then address it immediately. Just don't forget the vapor barrier and dehumidifier in the process.

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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.

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