Crawl Space Moisture Barrier for San Diego Structures

The majority of the times structures with a raised foundation or that have a crawl space have moisture problems occurring from beneath them. This is due to the moisture from the soil evaporating and rising to your crawl space, which commonly creates fungi, mold and other moisture related issues. San Diego Crawl Space Vapor Barrier This kind of issues will not only affect the health of your structure, but as well as the health of anyone spending time inside of it. The old solution to this problem was to install a certain amount of vents throughout the foundation to allow for cross ventilation. A major problem with this solution however was that exterior air is unconditioned; during the summer it allows hot air inside causing condensation and during the winter it allows cold air inside making the floors and the interior spaces colder and less energy efficient. Due to the inconveniences caused by passive crawl space ventilation a new solution emerged which is to seal the moisture and unconditioned air on the outside, leaving you with a crawl space that is clean and with a controlled environment. This solution will keep moisture out as well as allowing any existing or leaked moisture to dissipate and get out of your crawl space.

Unvented Crawl Space There are many steps that have to be taken in order to successfully seal your crawl space and maintain a comfortable level of moisture on the area. I will give you a quick overview of the different steps that need to be taken to accomplish this. The first step is to make sure that there are no areas that could bring water or moisture from the outside towards the interior of the crawl space. This could mean the installation of gutters on your house, and making sure that any currently installed are properly draining away from your property. It is very important as well to have a proper drainage; the slope grade away from your foundation should be no less than 5%, the equivalent of a 6-inch drop every 10 linear feet. The second step will be to clean the crawl space area to the best possible and remove any sharp object that might damage the vapor barrier. During this step the soil will be filled and leveled as necessary as well, gravel can be used t allow any moisture or radon gas to move and escape accordingly from underneath via optional exhausts. The next step will be to install a polyethylene vapor barrier, which is a minimum of 6-mil thickness. This vapor barrier or vapor diffusion retarders will extend a minimum of 6 inches from the above outside grade, but will not cover any wood members. The continuous poly vapor barrier will as well overlap all seams 1 to 2 inches and properly sealed. After the barrier has been installed all of the vents will need to be properly sealed with a Polystyrene block with a thickness of ½” to 2”. Finally the crawl space entrance will have to be sealed with a proper access panel.

By successfully creating this vapor barrier you prevent any soil moisture from moving into drier air, which is located in your structure. It will create a healthier and more energy efficient environment on your home. This will also make a big difference in preventive wood destroying organisms from entering your structure as it will create a physical layer as well as modifying the environment making it less ideal for them to flourish. Give us a call today at (619) 421-2101 and one of our licensed expert inspectors will go out to your property, evaluate your problem and provide you with a proper solution that will solve your specific situation. Remember that every property is different and it has to be treated accordingly.

Author Information:

Gilberto A. Cortez | Licensed Inspector
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