Plan Your Crawl Space Insulation Project

Plan Your Crawl Space Insulation Project Carefully

Crawl space insulation projects offer a few implementation options. Why? Crawl space insulation can be installed in the floor above or in the foundation walls enclosing the crawl space. Therefore, before starting any insulation work, homeowners must ensure the insulation surfaces remain dry and free from moisture contamination. Additionally, as a check, surfaces must show no signs of moisture or mold on the foundation or wood. Finally, if moisture exists, eliminating these problems becomes your number one priority.

Crawl Space Insulation Process

GreenHomes America recommends crawl space insulation for dry crawl spaces with a heating/cooling supply. Additionally, GHA recommends insulation for semi-conditioned spaces.

To start, permanently close any vents to the outside. Additionally, install a continuous vapor barrier over any exposed earth in the crawl space floor. This vapor barrier requires meticulous installation without any gaps, unsealed seams, or voids. Homeowners must ensure the barrier offers 100% continuous protection. The continues protection eliminates any moisture entering the space from the ground.

Finally, start insulating the top of the foundation wall area (called the rim joist) because this area maintains exposure to the exterior. Additionally, typically homeowners air seal and insulate the rim joist with spray foam. However, at times, homeowners rely on a combination of spray foam and batt insulation. Spray foam offers excellent air sealing protection. Spray foam seals the many air gaps in the rim joist and cut-to-fit batt insulation. As a result, this process helps raise the total R-Value well above the R-20 minimum.

Additionally, for many warmer climate zones, homeowners must leave an unobstructed 3” minimum termite inspection gap with no insulation between the bottom of the wood sill and the foundation wall. Upon properly insulating the rim joist, homeowners move onto insulating the moisture-free crawl space wall with spray foam or foam board insulation. Remember that foam insulations must be finished to meet minimum fire code requirements in your area depending the specific configuration of your crawl space.

Dry Crawl Space Insulation Projects

For dry crawl spaces with no heating/cooling supply or unconditioned crawl spaces, install insulation in the floor joists above the crawl space. However, homeowners must air seal all gaps, holes and voids before insulating the floor above the crawl space. This helps minimize insect entry points. Finally, after air sealing, install  insulation be installed in the floor system (to an R-38 or an insulation level sufficient to fill the framing cavity). For example, install insulation so it touches the plywood sub-flooring above it. In addition, ducts and heating pipes need sealing and insulation in the unconditioned crawl space.

Crawl Space Insulation Challenges

As you can see, insulating crawl spaces can be challenging. There are several options to consider and moisture problems are always a concern. And remember, crawl space insulation work can be extremely difficult and dangerous. To get the best results, it is usually wise to hire an experienced contractor that is trained and equipped to complete this type of work. An experienced contractor can help you determine:

  1. Are there any existing moisture problems such as areas of excessive condensation, running water or mold? If so, all moisture problems in the crawl space must be resolved prior to insulating.
  2. Are there any health and safety problems in your crawl space such as mold, asbestos or electrical hazards?
  3. Is it better to insulate the floor above the crawl space or the crawl space walls and why?
  4. Do I need to install vents in my crawl space if I don’t have any or close up vents if they exist currently?

A quality contractor ensures all of the holes or connections between the house and the crawl space for chimneys, plumbing piping, electrical wires, heating ducts and communication wires remain sealed with the proper sealants, caulks, spray foams or air-tight boxes. Remember, air sealing in crawl spaces around chimneys and fire rated walls must follow methods and rely on materials appropriate for higher temperatures. Experienced contractors possess the knowledge to do this properly. Talk to an experienced contractor about properly insulating your crawl space today!