Breaking Down Crawl Space Insulation Cost

Nailing down crawl space insulation cost can be difficult. Many factors, including the square footage of insulation required, type of insulation you’ll be using, and whether you’ll be having it professionally installed will all impact the cost of your crawl space insulation. Additionally, you’ll need to have your crawl space cleaned out and any old insulation hauled away, which may also impact the final cost. Consider using a crawl space cleaning service to help you get rid of mold, old fiberglass insulation or foam and start with a new crawl space foundation! 

The best way to understand how much it will cost to insulate the crawl space in your home is to have a professional appraisal done. However, before your appraisal, it’s important to understand what factors affect the cost of crawl space insulation. While things like the size of your house will have a big impact on the final cost of your project, you should also be aware of other common issues like the presence of mold or water damage that can increase expenses. Understanding these issues can help you gain a better idea of the potential scope of your project before you dive in with an insulation contractor.

What is a Crawl Space?

A crawl space is a type of foundation used in many parts of the country when other foundation types, such as slab-on-grade or a basement, are either less desirable or cost-prohibitive. There are three types of crawl spaces; open, unvented, or a ventilated crawl space. It is important to know which type of crawl space you have before moving forward with the insulation process. Crawl spaces may be an advantageous foundation type when:

  • There is excessive moisture present, 
  • The soil is sandy which is common in coastal areas, 
  • Or when the freeze-thaw cycle poses a threat to other foundation types like slab-on-grade.

Crawl spaces create a gap between the ground and the first floor of a home. The ground in the crawl space may be covered with a vapor barrier, or may simply be dirt or gravel. Above the ground is a gap, usually between 1-3’, before the subfloor of the home.

A core advantage of a crawl space over other foundation types is that you’ll have easy access to core mechanical systems of your home. These include things like your HVAC ducting, electrical, plumbing and insulation, which typically would require extensive work to access in homes with other foundation types.

How Are Crawl Spaces Insulated?

There are different ways to set up a crawl space, and those design decisions can have a big impact on the air quality of your home as well as how well or poorly your home deals with moisture. At the center of these decisions are where to place a foam or fiberglass insulation and create a vapor barrier.

There are three broad categories of crawl spaces: vented, unvented, and open. Let’s take a look at each in greater detail.

  • Vented – Vented crawl spaces are the most common type seen in many parts of the country. These crawl spaces have vents that passively circulate air with the outside. In a vented crawl space, the insulation is typically installed at the subfloor, in between the floor joists. This leaves the crawl space itself uninsulated, and everything from the subfloor and above is in the conditioned space of your home.
  • Unvented – Unvented crawl spaces are less common but can have a number of advantages over vented crawl spaces. Unvented crawl spaces are best thought of as a mini-basement. In unvented crawl space, insulation is typically installed along the walls of the crawl space rather than at the subfloor, while the ground is covered in a moisture barrier and may have some type of flooring. The most important distinction is that an unvented crawl space is considered part of the conditioned space of your home, and no longer passively exchanges air with the outside.
  • Open – Open crawl spaces are completely open to the outside. Typically surrounded only by lattice fencing or wire mesh, open crawl spaces achieve significantly more air circulation with the outside than even vented crawl spaces. These types of crawl spaces are less common than vented, but they do eliminate some of the moisture issues that can arise with a vented crawl space.

Though vented crawl spaces are more common, research has shown that they tend to perform more poorly than unvented crawl spaces. This can lead to a need for crawl space repair in the future. However, the advantages of an unvented crawl space include:

  • Higher energy savings
  • Less fluctuation in temperature
  • Less moisture and mold
  • More durability
  • Better air quality

The key problem with traditionally vented crawl spaces is that they were often installed without much regard to how moisture could affect the house over time. In houses with traditionally vented crawl spaces, the temperature of the ground and air in the crawl space is a few degrees cooler than the outside. During summer months the warmer outside air enters the crawl space and begins to cool. As it cools the moisture in the air forms condensation. In most traditionally vented crawl spaces that moisture forms on the underside of the subfloor, on and below the insulation and floor joists.

Over time the condensation forming in your crawl space will lead to enormous issues. Water left on wood will begin to form mold, and wet insulation will begin to perform more poorly. Additionally, the water will wick upwards deeper into the subfloor, potentially damaging your flooring.

Recognizing and managing the moisture that comes with vented crawl spaces is essential. Too often homeowners ignore their crawl space, which allows moisture to build up, mold to form, and damage to their insulation, subfloor, and flooring to occur. Consider adding in a moisture barrier to your crawl space to prevent these issues from arising quickly.

Crawl Space Insulation Cost Break Down

Here are the top factors that will influence the cost of replacing your crawl space insulation. These include:

  • Square footage of your crawl space.
  • Type of insulation used.
  • Whether your crawl space is vented or unvented.
  • Removal of old insulation.
  • Mold, water damage, or pest damage cleanup and remediation.
  • Cost of a vapor barrier and installation.
  • Labor.

So how much does crawl space insulation cost? The best way to find out is to have an inspection done by an insulation contractor and get a quote. The costs will vary depending on the type of insulation used. Fiberglass batt insulation tends to be more common and cheaper, while foam insulation tends to be less common and more expensive.

If your crawl space was set up correctly and no moisture damage or mold growth is present, replacing your crawl space insulation can be a relatively low-cost method of improving the energy efficiency of your home. 

However, costs will be higher if water damage or mold growth needs to be repaired. One issue with water damage in crawl spaces is that it can lead to cascading repairs. As the water wicks upward it damages the subfloor and eventually will impact your flooring. Buckled or discolored flooring is very often the first sign of a problem for many homeowners that don’t have their crawl space cleaned and inspected regularly. A crawl space repair may add to the overall cost but is a necessary step before starting new. 

The best way to avoid those negative outcomes is to have your crawl space regularly inspected and cleaned. A professional crawl space inspection can quickly give you a good idea about the current state of your crawl space. If it’s been neglected, an inspection will give you a good idea about what needs to be addressed and what the potential cost of that project might be. 

The Importance of Professional Installation

Though there are many DIY projects around a home where it can be financially beneficial to do the labor yourself, you should strongly consider having your crawl space insulation professionally installed. Professional crawl space insulation installation cost tends to be worthwhile even if you are handy or inclined to do the work yourself. 

Here’s why:

  • Most crawl spaces weren’t originally designed with sufficient moisture protections in place. In order to protect the durability of your home and the health of everyone living in it, it’s critical to ensure moisture mitigation and management measures are put into place during the replacement process. This may include using a vapor barrier or even converting your vented crawl space into an unvented, conditioned crawl space. Understanding the best option for you will require professional consultation with experts that understand crawl spaces.
  • Professional installers know that any air gap in the vapor barrier will result in damage down the road. That’s why great care is taken to ensure that an intact vapor barrier is maintained to protect your insulation and subfloor for years to come. Consult with a professional to insulate crawl space walls and floors to ensure proper measures are taken.
  • Existing water damage or mold growth will need to be identified and remediated before progressing further. Not doing so will simply seal in the moisture, negatively impacting the air quality in your home and resulting in even larger repairs down the road.

Closing Thoughts

The best way to get an accurate idea of how much it will cost to replace your crawl space insulation is to have a professional inspection done. There are a number of factors that can impact the cost of a crawl space insulation project, including the size of the crawl space, the type of insulation used, and whether there is existing mold and water damage that needs to be addressed.

We highly recommend that you have an inspection of your crawl space done, and have your insulation replacement completed by professionals. Many crawl spaces were built with insufficient attention to moisture issues, which has resulted in huge problems for some homeowners over time. Avoiding those problems all over again means addressing them during the removal and attic insulation installation process.

Aren’t sure if your crawl space insulation needs to be replaced? Have an inspection done by our professional team at Attic Construction! A crawl space inspection is a great place to start and should be done on a regular basis by all homeowners. A quick inspection now can help you avoid costly repairs down the road. To schedule an inspection or get a quote for crawl space insulation replacement, contact us today!


  1. “Guide to Closing and Conditioning Ventilated Crawlspaces”
  2. “How to Inspect and Correct a Vented Crawlspace” space.htm
  3. “What is a Crawl Space?”
  4. “Crawlspace Insulation” space-insulation

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