Crawl Space Insulation

Proper insulation and air sealing of your crawl space are vital maintenance tasks and smart financial decisions that can lead to significant savings. Insulation also helps improve the overall comfort of your home by maintaining a consistent indoor temperature and eliminating drafts. This approach to crawl space care ensures your home is not only more energy-efficient but also provides a comfortable living environment year-round.
installing crawl space insulation

Should I Insulate My Crawl Space?

Crawl space insulation is vital to making your home energy efficient while keeping it warm in the winter and cool in the summer. Many crawl space repair contractors try to talk homeowners out of properly insulating and air sealing the crawl space. We feel this is a mistake because local and national building codes require a crawl space to be insulated.

Make sure the company you choose to perform work on your crawl space is familiar with local codes when it comes to crawl space encapsulation and insulation.

Foundation Wall Insulation

Crawl space encapsulation projects require foundation wall insulation like InsulBarrier or foam board. When installing crawl space insulation during the encapsulation process, foundation wall insulation is a great way to keep your crawl space comfortable.

Wall insulation is applied to the block wall or concrete wall in order to create a thermal barrier between the cold or warm wall and the crawl space. Just like attic insulation is designed to stop the thermal transfer of heat and cold from your living space to the crawl space.

Crawl space walls that are uneven like stone or old brick, may require a closed cell spray foam to properly insulate due to uneven surfaces. We recommend installing all foundation wall insulation mechanically, when possible, due to adhesives failing over time.

Another benefit of moisture resistant foundation wall insulation versus fiberglass is it can get wet without needing to be replaced or lose its R-value.

“If your home is as little as 5 to 10 years old, you likely have one of the 46 million under-insulated homes in the United States.”

The Harvard School of Public Health

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Fiberglass Insulation

Fiberglass batting insulation or rock wool insulation is typically the choice of insulating a vented crawl space or non-conditioned crawl space. When air is allowed to freely flow in and out of the crawl space, installing a batting insulation to the sub-floor helps create a thermal barrier between the crawl space and the living space.

Spray Foam Insulation

Air sealing the crawl space with spray foam insulation or polyurethane caulk is probably the most overlooked way to insulate the crawl space.

The engineers at recommend air sealing the rim joist to ensure air movement is minimized up the outer walls of the crawl space and into the living space or attic. They refer to this as a “Critical Seal” and we recommend that every crawl space and basement have the rim joists air sealed properly.

Spray foam insulation is also great to air seal all of the plumbing, electrical and HVAC penetrations in the crawl space. Some spray foams may off gas for 48 hours or even longer. This means that you should not enter the space until the off gassing is complete. Crawl Space Ninja only uses GreenGuard Gold Certified spray foam when air sealing the crawl space subfloor and rim joists. GreenGuard Gold Certified spray foams only require a 1-hour off gassing period and allows for lower VOC transmission levels versus cheap spray foam products.

Many crawl space contractors overlook air sealing large gaps in exterior cinder block walls as well. Make sure these are air sealed to keep the air transfer from the outside at a minimum. This may also help keep standing water from infiltrating the crawl space but normally that is better addressed in other ways.

The Best Insulation for Crawl Spaces

Watch Michael Church discuss the best insulation methods for crawl spaces based on a scientific study. For more informational videos, check out our homeowner tips and guides on our YouTube Channel.

Need insulation for your home? Drop us a line today to schedule an assessment.

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