Learn about Insulating the Crawl Space in Your Home

Crawl spaces come in three types: conditioned, semi-conditioned or unconditioned spaces. As a result, conditioned crawl spaces are intentionally heated or cooled. Frequently, these spaces contain insulation in the crawl space walls without any insulation between the crawl space and the house above.

Semi-conditioned crawl spaces are unintentionally heated or cooled. Frequently, these spaces do not contain any insulation in the walls or in the floor above. And, unconditioned crawl spaces have insulation in the floor above the crawl space without a positive heating or cooling supply to the crawl space.

Finally, unconditioned crawl spaces usually contain vents in the wall of the crawl space. Also, these vents connect the crawl space with the outside air. NEVER insulate the walls of a crawl space that vents to the outside. As a result, if the foundation wall of a vented crawl space requires insulation, the vents must be closed, sealed or removed.

Regardless of the type of crawl space you have, all crawl spaces need insulation in the floor above or in the foundation walls enclosing the crawl space. Insulating your crawl space reduces energy use all year long. Additionally, crawl space insulation requires no maintenance. Plus, if installed properly, it provides energy efficiency for  a very long time. However, homeowners must check and fix any moisture problems prior to implementing crawl space insulation.

Measuring Crawl Space Insulation Performance

R-value measures the insulation performance in crawl spaces (and all other parts of your home). For reference, R-value measures the ability of insulation to resist heat flow. The higher the R-value, the better the insulating capacity. Additionally, GreenHomes recommends R-38 insulation in floors over unconditioned crawl spaces (or insulation sufficient to fill the framing cavity). Conversely, GHA recommends R-20 minimum in conditioned crawl space walls. For insulation to minimize the flow of heat loss, homeowners need proper installation, which includes:

• Dry and away from moisture sources – Insulations works better when installed properly. Proper installation means avoiding contact with moisture sources. For example, in basements or crawl spaces, ensure the insulation surfaces remain dry and free from moisture contamination.
• Continuously with no gaps – All insulation requires installation without any gaps, voids or spaces. It requires 100% continuous installation.
• To the proper thickness – Compressing insulation decreases its insulating ability. Proper installation includes the correct thickness.
• With NO air flowing through it – Air movement through insulation reduces the insulating capability. Therefore, air sealing crawl spaces prior to insulating stops air movement through the insulation.