Crawlspace Moisture
In our area it is more common to have a basement than a crawlspace, however I still inspect them often. Recently, I inspected a crawlspace that contained a lot of moisture. It was a vented crawlspace, the ground was wet and muddy, and there were signs of moisture wicking up the wood support columns.
Where was all this moisture coming from?
- Rain and Groundwater: This is the main source of moisture that you will find in your home. Rain and groundwater can wick through the porous concrete material and flow through any holes or cracks that you may have in your foundation.
- Water Vapors in the Air and Soil: These vapors can flow through any unsealed penetrations you may have between the conditioned and unconditioned spaces as well as wick through the porous concrete material.
How can we manage the moisture levels in our crawlspace area?
The quickest and easiest way to manage the moisture levels in our crawlspaces is ensure all the water running off the roof is directed away from your home at the exterior.
- Gutters: Properly installed gutters will direct all that water away from the foundation.
- Positive Grading: A positive slope away from your home will also keep the water from building next to your foundation.
- Vapor Barrier at the Interior: A properly installed vapor barrier is the most important factor to eliminate moisture movement from the soil into the crawlspace environment.
Here are some other areas to look at:
- Sprinkler systems should be directed away from the home.
- Crawlspace access can also allow water into the crawlspace. Ensure that there is an weather seal present and the covering is constructed with non-corroding materials
In this particular home there were no gutters, the grade was sloping towards the home in some areas and there was no vapor barrier at the crawlspace floor. In addition all the exterior vents had been covered, which limits the flow of cross ventilation that can help prevent moisture in the space.
Floor Vapor Barrier Installation
- The entire crawlspace floor should be covered with a minimum 6-mil poly vapor barrier.
- Each vapor barrier sheet should overlap and be sealed together.
- The vapor barrier should extend up the foundation wall and be sealed tight.
- All penetrations should be sealed around to prevent the moisture from escaping.
Water is your home’s worst enemy and can cause significant damage if not addressed. I often tell my clients, “Welcome to home ownership. Homes take maintenance and love”. And it is true. You have to give your home a little bit of love here and there and it will take care of you for a very long time.