Should most crawl spaces be closed?

Most crawl spaces should indeed be closed, and this approach is recommended for several reasons related to moisture control, energy efficiency, and overall building performance.

When crawl spaces are closed, it helps to maintain a controlled environment that minimizes the chances of moisture accumulation. This is important because excess moisture can lead to problems such as mold growth, rot, and deterioration of building materials. In a closed crawl space, incorporating a vapor barrier also helps prevent ground moisture from seeping into the space, further protecting the home's structure and air quality.

Additionally, closed crawl spaces can contribute to improved energy efficiency. They can be sealed and insulated, reducing the amount of outside air that infiltrates the home. This results in a more stable indoor temperature and lower heating and cooling costs since the conditioned air remains more contained within the living spaces.

In contrast, options like leaving crawl spaces open to promote airflow may be misleading. While it was once thought that air circulation would help mitigate dampness, modern building science supports that closed crawl spaces (especially when properly encapsulated) offer better protection against moisture-related issues and enhance insulation effectiveness.

Considering these points helps to underscore why closing most crawl spaces is often the preferred and more effective approach.