What is the Best Crawl Space Insulation?

crew installing crawl space insulation panels

Insulation is an important material in home construction. It keeps the chilly winter winds and stifling summer heat out so you can enjoy a comfortable temperature inside your home.

This is crucial for your crawl space, as this area greatly influences indoor living conditions. You have many insulation options, so how do you know what to choose?

This article covers everything you need to know about this vital material, helping you choose the best crawl space insulation and make an informed decision for your home.

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Crawl Space 101: Building and Materials

When constructing a home with a crawl space, builders dig a hole in the ground, pour concrete footers, and construct the foundation walls. Unlike a basement, a crawl space is a hollow space that elevates the home about 1 to 3 feet off the ground. Typically, the dirt crawl space floor remains exposed or is covered with a very thin—and very ineffective—moisture barrier.

Some crawl spaces have insulation added to the rim joists or between floor joists, and some do not. One reason for insulation in the floor above is that the crawl space is so cold in the winter due to open vents. These vents should be closed permanently, which makes a huge difference in the temperature of the floor above.

To learn more about crawl spaces, check out our Crawl Space Encapsulation page.

Crawl Space Insulation Options

Insulation comes in all shapes and sizes. Let’s dive into the top three crawl space insulation materials:

1. Fiberglass Insulation

failing fiberglass insulation in a crawl space

Fiberglass is a popular and economical option that is widely used in homes across North Carolina and the globe. However, it does not belong in a crawl space.

This material is loose, and air passes right through it. When it is between the joists in a vented crawl space, with the paper or foil side up and the unfaced side down, it’s not doing much at all. Additionally, paper-faced insulation is mold candy; mold loves paper even more than wood! The same goes for bugs and other critters.

Lastly, when fiberglass insulation is even a little damp, it loses much of its insulation value.

2. Spray Foam Insulation

While spray insulation is often used on crawl space walls, floor joists, and rim joists to help regulate temperature year-round, it also may not be the ideal solution for these areas. Alternative insulation methods might be more appropriate for crawl spaces.

Typically, spray insulation consists of closed-cell foams, which offer rigidity and durability. However, this doesn’t make them impervious to all forms of damage. In the moist environment often found in crawl spaces, spray foam insulation can become problematic. It may foster mold growth, release unpleasant chemical odors, and potentially attract termites, leading to structural damage.

3. Foam Board Insulation

So, if the other two methods don’t work, what does? Foam board insulation is the best crawl space insulation material that provides ultimate temperature control.

Thick, moisture and mold-resistant panels cut to fit your unique crawl space are fastened to crawl space walls and rim joists. They can also seal open crawl space vent cavities and are compatible with various crawl space encapsulation methods, giving your crawl space the comprehensive protection it deserves.

Important Insulation Factors

Before making this important investment, you also need to consider other crawl space insulation properties, including:

R-Value

R-value is a measure of an insulation material’s thermal resistance to heat flow. The higher the R-value of a material, the stronger its insulation power. The R-value of insulation depends on the type of insulation, its density, and thickness.

Any material with an R-value of 7 or above makes for good insulation material for the crawl space. Such insulation will reduce heat transfer to the outside. Various factors determine the type of R-value that your walls need, including your local weather, the type of HVAC unit you have, and which part of your house needs insulation.

Fire Resistance

Many types of insulation are combustible and aren’t suitable for the crawl space area. What your crawl space needs is Class-A-rated insulation. The Class A fire rating is the highest standard given to building or insulation materials in the construction industry.

These materials have a flame-spread rate between 0 and 25. Because of what they are treated with during manufacturing, Class-A-rated materials tend to spread flames slower than other materials. It’s this property that makes them effective against various fires, particularly those arising from combustibles.

Pest Resistance

Termites are invasive critters that destroy property worth billions of dollars and injure trees. They chew up wood, papers, books, and insulation liners, amongst other materials. A typical treatment involves a chemical treatment application known as a termiticide.

When insulating your crawl space, consider using Tar Heel Basement Systems’ exclusive ExTremeBloc™ insulation panels. This material contains termiticide, which eliminates termites that try to nibble through your insulation. Our team also installs them with an inspection gap, allowing exterminators to inspect and treat the area for potential infestations.

Need Help Insulating Your Crawl Space? Contact Tar Heel Basement Systems Today!

Tar Heel Basement Systems inspector looking at crawl space insulation

Crawl space insulation can make or break your home’s living environment. By sealing all outside air leaks and insulating the walls, the crawl space is part of the conditioned space of the house. This can be a complex process and not something you should tackle on your own.

Trust our expert team at Tar Heel Basement Systems to properly insulate and encapsulate your crawl space. Homeowners throughout North Carolina count on our more than 20 years of experience and customized solutions. Gain peace of mind knowing your home is protected by the best in the business. Contact us to schedule a free inspection and estimate today!

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Crawl Space FAQs

Can I dry and reuse wet crawl space insulation?

Reusing wet fiberglass insulation is not advisable as it loses insulation efficiency and may harbor mold. Tar Heel Basement Systems installs durable, water and mold-resistant rigid insulation panels. Contact us for a no-cost inspection and repair estimate.

How often should crawl space insulation be replaced?

Many insulation materials typically last 15 to 20 years. However, their lifespan can be shorter in crawl spaces with moisture and mold issues. Quality insulation like ExTremeBloc™ is designed to be long-lasting. Contact us to learn more and schedule a free inspection.

What does crawl space insulation cost?

Costs vary based on crawl space condition, size, and required solutions. We provide free inspections, no-obligation repair estimates with detailed pricing information, and various financing options.

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Holly Richards-Purpura

Content Writer

Holly is a Content Writer for Groundworks who has written and edited web content for the foundation services industry for almost 10 years. With a background in journalism, her passion for the written word runs deep. Holly lives in Columbus, OH, with her husband. Along with educating homeowners, she also has a big heart for the Big Apple.