Old crawlspace engineering had builders putting vents on either side of your house. The thinking was that, when open, they would create a through breeze in the crawlspace that would help to keep the area dry.
Unfortunately this is not how it works. In reality, in warm weather, the air comes in from both sides of the house and moves upward in a chimney like effect. The moisture moves upwards to the living area and collects on every cool surface it meets in the form of condensation.
Plus, during the winter, the vents increase heating costs for your home by sucking in cold outside air under the house.
Some obvious signs of too much ventilation in your crawlspace include:
• Soggy insulation during the summer
• Cold ground level floor during the winter
• Muddy crawlspace
• Rot on framework
• Rusty duct and metal posts
Fortunately, there is a better solution these days. By encapsulating your crawl space with a vapor barrier, you can successfully manage your moisture problem. The floor and walls of the crawl space , plus any gaps or holes to the outside of the house, are sealed with the vapor barrier. All vents will be given airtight covers. This will effectively keep the moisture out of your crawlspace and preserve the area.