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How Crawl Space Insulation Works & 6 Steps to Lower Your Energy Bills

Groundworks provides top-notch crawl space insulation services for homeowners across the country.
You’re probably already familiar with your home’s crawl space (if you’re not, it’s the 1-3ft high, dirt-floored space below the first floor of your home).
Crawl spaces play a crucial role in elevating houses from the ground and providing a designated area for important home components like air conditioning and heating units, duct work, plumbing, electrical wiring, and insulation. However, if they’re not sealed and insulated, they’re vulnerable to moisture intrusion and variations in temperature. And that effects your entire house.
Insulation is just one (major) part of crawl space encapsulation , and encapsulation protects your home against mold, wood rot, high electric bills, and other crawl space problem signs. But insulation works to ward off the effects of extreme temperatures on your home, keeping your HVAC system working at a manageable rate.
Crawl space insulation means lower energy bills in the summer and winter. In fact, comprehensive crawl space encapsulation can actually reduce your energy bills by up to 18%.
Here’s how.

How Does Crawl Space Insulation Lower Energy Bills?

Insulating your crawl space increases the barrier between the outside of your house and the crawl space, which is often cooler because it’s close to the ground. Insulation helps to keep the temperature inside your house more stable, which means you’ll need less heat in the winter and less air conditioning in the summer. This reduces how much energy your heating and cooling systems use, and the less energy you use, the more you save. That’s how crawl space insulation lowers your energy bills.

Now, let’s get technical.


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The Basic Tools of Crawl Space Insulation

Crawl space insulation involves waterproofing your crawl space and protecting areas that are susceptible to moisture damage or temperature changes (floor joists, foundation walls, and dirt floors).


The R-value is a measurement used to determine how effectively an insulation material prevents the flow of heat into and out of a home. Essentially, it represents how well the material resists heat transfer. The R-value is determined by the type, thickness, and density of the insulation material, and higher R-values indicate better performance and greater energy savings. Insulation materials with higher R-values improve the overall energy efficiency of your home.

Vapor Barrier

One essential component of crawl space insulation is a vapor barrier, which is attached to the floors and walls to mitigate moisture from the surrounding air and ground. Its primary function is to prevent moisture from seeping into the space and getting the insulation wet. If insulation gets wet, it loses performance. At Groundworks, we use our very own 20-mil thick CrawlSeal™ vapor barriers that are designed to the industry’s highest standards and come with extensive warranties to keep interior temperature well-regulated for the long haul.

Thermal Insulation

Once a vapor barrier is installed beneath your home, the next step is to put in the actual insulation. Many companies put in standard dry wall insulation. Combined with minimal vapor barriers, these fail with the first rain, grow moldy over time, and end up sitting in a pile on the dirt floor of your crawl space.

A better alternative is foam board insulation. Foam board insulation provides an additional layer of defense for your crawl space, further improving its energy efficiency and ensuring a comfortable living space.

At Groundworks, we use ExTremeBloc™ , which features a polystyrene body wrapped in graphite, environmentally friendly components, built-in pest deterrents, and an R-value of 11, making it one of the best insulation boards on the market.

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Insulated crawl space with ExTremeBlocâ„¢

6 Steps to Effectively Insulate Your Crawl Space

Now that you have a basic understanding of the components of crawl space insulation, it’s time to take a closer look at the steps involved in insulating your crawl space. This process typically involves cutting off any sources of moisture or outdoor air that can compromise the performance of your insulation materials.

Working in a crawl space can be difficult and potentially hazardous, so we recommend hiring professional services for the job. Groundworks has local locations across the United States, and our team of experts is always ready to help you install crawl space insulation that meets your needs and budget. By working with us, you can enjoy peace of mind knowing that your crawl space is properly insulated and protected against moisture, temperature fluctuations, and pests, all while potentially reducing your energy bills.

1. Remove Moisture and Clear Mold 

The first step in insulating your crawl space is removing any moisture below your home and identifying any access points that moisture can get through. Open vents, exposed dirt floors, and previously damaged insulation all lead to high levels of water below your home. Removing existing moisture and mold is crucial for creating a healthier environment in your crawl space.

2. Fix Any Cracks and Structural Damage.

A professional crawl space repair company will check the crawl space for cracks and structural damage, then perform the necessary repairs before installing the insulation material on your walls. The reason for this is simple: a dilapidated crawl space that is literally falling apart will only continue to create moisture, mold, and temperature issues for your home.

3. Seal Crawl Space Vents and Other Openings 

Once you’ve cleared out moisture and mold, and identified major access points for moisture, the next step is to close them off. A vapor barrier installation helps prevent the stack effect from lifting humid air into your home and stops groundwater from evaporating into the crawl space. Crawl space vent covers can be used to close open vents and prevent humid air from seeping below your home during the summer. Dehumidifiers can also remove lingering humid air for extra dry protection. Lastly, installing a sump pump and interior drainage system helps quickly move groundwater away from your crawl space after a heavy storm. 

4. Install Moisture Control Equipment

There are different waterproofing solutions. We’ll help you find waterproof insulation along with interior drains and a sump pump system. If humidity is high, we encourage you to get an energy-efficient dehumidifier to dry out the air. This way, you’ll avert moisture problems and prevent water damage and associated repairs.

5. Attach Insulation

Now that all moisture is removed and prevented, insulation can finally be installed without fear of damage.

Fiberglass batt insulation has been a traditional choice for insulating crawl spaces due to its affordability and easy availability. However, it has several drawbacks, including the ability to absorb moisture, harbor pests, and sag or fall out of place. While fiberglass is a viable option for crawl space insulation, it may not be the best choice.

A more effective alternative is rigid foam insulation board. insulation boards are a common tool used for crawl space insulation, but these other options may also be used:  

  • Radiant barriers 
  • Liquid foam insulation 
  • Blankets, batts, and rolls 
  • Loose fill and blow-in insulation 

However, with years of experience, Groundworks recommends installing ExTremeBloc™, a foam insulation board that keeps your entire crawl space energy-efficient and temperature controlled with ease. You will also want to keep in mind that the U.S. Department of Energy recommends insulation with an R-value of at least 9 for below floor protection

6. Encapsulate with 20-Mil Plastic Vapor Barriers

We always advise homeowners to pair crawl space insulation with encapsulation. This entails covering the crawl space floor and walls with a 20-mil plastic barrier. What this barrier does is isolate the crawl space area from the earth and outside air. In addition, encapsulation protects your utilities from water, moisture, and mold, and makes it difficult for pests to get inside. We can help you with encapsulation if you intend to use the barrier as your secondary waterproofing solution.

While it is possible to install most of these materials on your own, the tools needed for the job are expensive, and the work you have to do is very extensive. Hiring a professional like Groundworks for your crawl space insulation project is going to save you time – and you can feel better knowing the job will be done right the first time. 

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The Benefits of Crawl Space Insulation for Your Home

Crawl space insulation is a smart investment that can help you save money, improve your home’s comfort, and increase its overall value.

Improved Air Quality

Insulating your crawl space offers numerous benefits, including improving the air quality inside your home. With crawl space insulation, the space between your floor and the ground is sealed off, preventing pollutants and allergens from getting trapped inside. This feature is particularly beneficial for individuals who suffer from allergies or asthma, as they are more sensitive to airborne irritants. In fact, according to the Environmental Protection Agency, indoor air can be up to five times more polluted than outdoor air. Crawl space insulation can help mitigate this issue and promote a healthier indoor environment.

Protects Against Mold

Insulating your crawl space creates a barrier between your home and the damp, cold environment below, preventing mold growth and promoting a healthier indoor environment. In addition, insulation eliminates the usual warm, wet, and humid environment that typically characterizes crawl spaces which discourages pests from burrowing under your home and causing damage.

Deters Unwanted Pests

Crawl space insulation creates an inhospitable environment for unwanted pests, such as rodents and insects, that often find their way into homes. Without insulation, crawl spaces can be a warm and humid environment, which is attractive to pests. However, insulation helps to eliminate the moist and warm conditions that pests thrive in, making it difficult for them to survive. Insulation can also seal off access points that pests use to enter your home through the crawl space. With insulation, your home can become a less inviting environment for unwanted pests, making it easier to keep them at bay and protect your home from damage.

Improves Energy Efficiency

Crawl space insulation can greatly enhance the energy efficiency of your home by creating an airtight seal that helps to maintain a comfortable indoor temperature year-round. In fact, the U.S. Department of Energy cites that properly insulating your crawl space can save up to 18% on your energy bills.

In the winter months, insulation retains heat and prevents cold air from seeping in, keeping your home warmer and lowering your heating bills. Conversely, during the summer months, it helps keep your floors cooler, which eases the workload of your air conditioner and reduces cooling costs. By investing in crawl space insulation, you can enjoy significant energy savings and a more comfortable home, regardless of the season.

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Groundworks Helps Insulate Your Crawl Space 

At Groundworks, we understand the importance of a healthy crawl space. In fact, with 45 local offices throughout the country, we know how different environments impact your crawl space. Armed with that expert knowledge, we get the job done right every time, no matter where you are located. Your crawl space deserves to be masterfully insulated – we can help. 

Since our company’s inception, Groundworks has helped nearly 1.5 million homeowners address their foundation problems. We’re committed to world-class service, and thousands of positive online reviews only prove this point further. If you want to keep your crawl space as protected as possible, contact us today to schedule a free inspection!