Crawl Space Repairs Missouri

Crawl Space Moisture Barrier | Crawl Space Moisture Damage Repairs

Crawl spaces naturally offer ideal conditions for mold to grow, especially in Missouri.   Most people never hear about this mold / fungal growth (problem) until they go to sell their home and their home inspection states that there is dangerous mold in the crawl space that must be remediated.  The first thing that must be addressed is the source of moisture.  If there is mold, there is moisture.

Here are a few questions you need answered before determining the solution to your problem.

What does mold need to grow?

When inspecting a crawl space some things you need to check for first:   the humidity in the crawl space and the moisture content of the floor joists.  The relative humidity needs to be under 65% and the moisture content (of floor joists and subfloor) needs to be under 16%.  Once the relative humidity rises above 50% and 70 degrees your crawl space becomes an ideal spot for mold to grow.  This is why we say there will be some fungal growth in most crawl spaces where the outdoor humidity is high.  When a crawl space is above 65% RH there is danger of damaging the structure and causing damage inside the home.


There is moisture / water in my crawl space, how did it get there?

Typically, a majority of the moisture in the crawl space is a result of hydrostatic pressure.  This happens when the soil around, and under, your crawl space becomes saturated with water.  This water can enter through your foundation walls or just rise up from the ground.  You will especially notice the effects of hydrostatic pressure during heavy rains, when the water table rises.


There is standing water in my crawl space, what do I do?

If there is standing water in your crawl space the solution is to have a sump pump installed.  You want to have your sump pump located in the lowest part of the crawl space.  This is accomplished by placing your sump pump in a 3 foot deep hole in the lowest part of your crawl space.  So, as the water table rises, the sump pump begins to pump out the water before it enters the crawl space.

crawl space repair

The humidity in my crawl space is above 65%, what should I do?

The high humidity in your crawl space is caused by the moisture in the ground evaporating into the air.  Once the air evaporates in the crawl space it becomes trapped and it has nowhere to escape to.  This is why it is essential to have a moisture barrier installed.  When having a moisture barrier installed you must make sure it runs up the foundation walls and is taped at the seams (with waterproof tape).  This will keep any moisture under the barrier and out of the crawl space.


There is mold/ fungal growth on my floor joists, what should I do?

If there is mold / fungal growth on the floor joists in the crawl space you need to check three things:

  •  is there standing water in your crawl space
  •  is the relative humidity in your crawl space above 65%
  •  are the floor joists above 16% moisture content.

If there is standing water, you need to install a sump pump.

If the relative humidity is above 65%, you need to install a vapor barrier.

If the floor joists are above 20% moisture content, you need to install a vapor barrier.


Then, once you get rid of your moisture problem, you can focus on removing the mold.  But, theres no reason to remove the mold before you fix the source of the water.  


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