In most cases when installing a vapor barrier in your crawl space you will have two options. Install the vapor barrier over the soil only (not on top of anything). This means the vapor barrier will be touching moist earth, which is fine as long as proper ventilation is provided. Install vapor barrier on top of crawl space items first and then cover it with plastic sheeting for vapor protection . However, this method requires more caution since you should not block any air vents or other openings that allow airflow into your crawl space. Water Damage restoration

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