A homeowner on his side with a flashlight pointed at the crawl space ceiling

Energy conservation is one of the requirements for a sustainable home. Unfortunately, most homes with crawl spaces lose energy from hot and cool air through these spaces. Insulating crawl space ceilings is one way to combat this energy loss and save money on heating and cooling bills.

This article will discuss the amount of energy you save by insulating your crawl spaces. We’ll also discuss the materials you can use to seal your crawl space ceilings.

So, let’s get started!

Is Insulating Your Crawl Space Worth It?

Insulating crawl space ceilings is worth the effort since it enhances comfort in rooms above the space. It also improves a home’s energy efficiency by reducing heat loss. On the other hand, uninsulated crawl space ceilings strain a home’s heating and cooling system, leading to higher energy costs.

How Much Energy Do Insulated Crawl Spaces Save?

Many homeowners use crawl spaces – which are between one to two three feet (0.3-0.9 meters) high – for storage or a place to run pipes, wires, and HVAC systems. 

Insulating crawl space ceilings can be challenging due to their low height. But without insulation, air flows freely through the crawl space, causing energy loss.

Moreover, most crawl spaces are unfinished to make it easier to access gas hookups, plumbing, wiring, and ventilation when needed. Unfortunately, the unfinished nature of these spaces is also a reason for considerable energy loss from the house.

A polyethylene vapor barrier in a crawspace.

Insulating or encapsulating your crawl space ceiling are excellent ways to conserve energy and lower your bills. According to Energy Star, insulating your crawl spaces helps save up to 15% energy.

Insulating your crawl space also prevents the ductwork from losing heat. In turn, this process reduces your heating and cooling costs.

Pros and Cons of Crawl Space Ceiling Insulation


  • Improved energy efficiency – insulating your crawl space protects your house from weather extremities like scorching summers and freezing winters. This reinforcement reduces strain on your heating and cooling systems, making them energy-efficient.
  • Saving you money – insulating your crawl space makes your home’s heating and cooling system more efficient. The result is low energy bills as the system uses less energy to keep the indoor environment conducive.
  • Preventing mold growth – effective insulation materials like fiberglass protects your crawl space from moisture accumulation. Moisture is one of the conditions necessary for mold growth and must be prevented at all costs.
A puddle of standing water in a crawl space
Courtesy of JES Foundational Repair
  • Enhanced comfort in rooms above the crawl space – unconditioned cold air can penetrate through the crawl space ceiling and affect the temperature in rooms above it. Therefore, insulating the crawl space ceiling helps maintain a comfortable indoor environment for these rooms.
  • Preserving indoor air quality – when air leaks through the crawl space and enters the living area, it can bring pollutants like mold spores. Insulating your crawl space seals off these air leaks, preserving indoor air quality.
  • Increased home value – crawl spaces are among the things potential buyers inspect. A well-insulated crawl space adds value to your home and makes it more appealing to buyers.


  • Higher upfront cost – depending on the insulation material you choose, insulating your crawl space may require a more significant initial investment. However, energy savings and improved comfort in your home will eventually offset the high initial cost.
  • Reduced crawl space storage – insulation may take up some of that space if you plan on using the crawl space for storage. However, this shouldn’t be a significant concern as crawl spaces are not meant for extensive storage.
  • Difficulty accessing pipes and wiring – insulation may make it harder to access crawl space pipes and wiring for maintenance or repairs. However, you can easily solve this by leaving a small part of the crawl space ceiling uninsulated to provide easy access to these components.

Best Materials To Insulate a Crawl Space Ceiling

Choosing the best material to insulate or encapsulate your crawl space boils down to the following factors:

  • Airtightness: You’re insulating the crawl space for efficient thermal management. A crucial consideration to achieve this is using an airtight material that seals any air leaks.
  • Moisture resistance: Crawl spaces are prone to moisture, so it’s essential to use a material that can resist water damage and mold growth. Often encapsulation is carried out alongside insulation for added moisture resistance. 
  • Durability: You need a material that can last for years without needing constant replacement or maintenance.
  • Cost: Crawl space insulating material comes at different prices. You need material that’s in line with your budget.

Based on the above factors, the following are the best crawl space insulation materials:

Fiberglass Batts

Fiberglass batts are made up of plastic reinforced by fine glass fibers. The combination of these materials strengthens the insulation capacity.

Fiberglass batts are cost-effective—the material costs between $0.3 and $0.4 per square foot (0.09 square meters). They’re also easy to install.

Fiberglass insulation being installed in the underside of a home attic ceiling, showing a beige fiberglass batt

However, fiberglass insulation is not airtight and may require additional material to seal off any gaps or cracks. Another drawback of fiberglass batts is that they can trap allergens and dust in the crawl space. These trappings can promote mold growth if not cleaned regularly.

Spray Foam

Closed-cell spray foam has an R-value between six and seven per inch, making it one of the best options for crawl space insulation. It seals off air leaks and can also resist moisture.

Another feature that makes spray foam suitable for crawl spaces is that it doesn’t retain water. Therefore, you can rest assured that the material will not create a conducive environment for mold growth in your crawl space.

It’s also worth mentioning that, unlike fiberglass, spray foam is not food for pests like rodents and insects.

Spray foam costs between $0.95 and $1.25 per square foot (0.09 square meters), making it one of the most expensive crawl space insulation materials. However, it’s worth the cost if you want efficient and durable insulation for your crawl space ceilings.

Rigid Foam Board

As we’ve discussed, your crawl space needs water-resistant and airtight insulation materials. Rigid foam is one such material.

Rigid foam is made from the following materials:

  • Extruded polystyrene (XPS) – costs between $0.58 and $0.7 per square foot (0.09 meters).
  • Polyisocyanurate (polyiso) – costs between $1.35 and $2.50 per square foot (0.09 meters).
  • Expanded polystyrene (EPS) – costs between $0.4 and $0.5 per square foot (0.09 meters).
Several pieces of XPS foam board insulation are displayed on a table

These materials have high R-values, ranging from 1-15, meaning rigid foam will have an R-value between 1-15, depending on your chosen material.

Rigid foam insulation is a durable and easy-to-install option. Moreover, foam boards are more substantial, strengthening the crawl space walls when used for insulation.

The downside of rigid foam is that it may not seal off air leaks, as with spray foam. Although it’s considered an airtight material, it requires additional sealing to prevent air leaks.

Cellulose Insulation

Cellulose in batt form is another suitable crawl space insulation material. The main advantage of batt cellulose insulation is that it is waterproof. Since a crawl space is exposed to high moisture, you need a waterproof material to prevent moisture accumulation and mold growth.

Batt cellulose also meets the requirements for eco-friendly construction since it’s made from recycled material. However, batt cellulose may not be as efficient as fiberglass or spray foam when it comes to insulation. It also requires additional sealing material to prevent air leaks in the crawl space.

Based on the cost of the materials, the average crawl space insulation cost is between $1,000 and $2,800.


Insulating your crawl space ceiling brings numerous efficiency advantages for your home’s thermal management and energy costs. First, however, you must choose a suitable material that is airtight, inexpensive, and offers both moisture resistance and durability. 

Taking these qualities into consideration, the best crawl space ceiling insulation materials are fiberglass batts, spray foam, and rigid foam.


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