Hemp insulation is gaining popularity as an eco-friendly alternative to fiberglass and spray foam, but is it the right choice for your home?
This plant-based insulation offers excellent moisture control, soundproofing, and thermal performance, but it comes at a higher cost—ranging from $1.40 to $3.10 per square foot, compared to $0.30 to $1.50 for traditional fiberglass.
While hemp insulation’s sustainability and performance make it a standout option, its cost and availability may be deciding factors. Here’s how to determine if hemp is worth the investment.
What Is Hemp Insulation?
Hemp insulation is a natural, plant-based alternative to traditional insulation materials. Made from industrial hemp fibers, it’s free from harmful chemicals and doesn’t irritate the skin like fiberglass. Unlike marijuana, industrial hemp contains less than 0.3% THC, making it non-psychoactive.
Most hemp insulation is 90% hemp fiber, with the rest made up of polyester fibers and non-toxic bonding agents that hold it together.
How Is Hemp Insulation Made?
Manufacturers process hemp stalks into fibers, which are then formed into batts or rolls. This process requires minimal energy, produces little waste, and results in a thick, compressible insulation material similar in texture to wool or cotton.
Not only is the hemp insulation product more eco-friendly than traditional insulation materials, but the manufacturing process is, too.
Availability and Legal Status
Yes! Hemp cultivation was federally legalized in 2018, allowing states to set their own rules for growing industrial hemp. As a result, it’s become more widely available across the country.
Eco-Friendly Benefits of Hemp Insulation
Sustainable Crop Production
Hemp is a fast-growing, low-maintenance crop that requires little water and no pesticides. It also helps improve soil health by preventing erosion and adding nutrients back into the ground.
Carbon Negative-Material
Hemp absorbs more carbon dioxide than it releases, making it a carbon-negative building material. Installing hemp insulation can help reduce your home’s environmental footprint.
Biodegradable and Recyclable
Unlike fiberglass or foam insulation, you can recycle or compost hemp at the end of its life, as it’s fully biodegradable. That means less waste in landfills.
How Well Does Hemp Insulation Perform?
Thermal Performance (R-Value)
Hemp insulation has an R-value of about 3.5 per inch, similar to fiberglass. However, you can compress hemp batts to fit standard wall cavities, increasing insulation power.
For example, installing a 5.5-inch batt in a 3.5-inch stud cavity boosts the total R-value to 19.25, which exceeds the insulation requirements for even the coldest U.S. climates.
To better understand insulation R-value, check out our informative guide.
Moisture Control
Hemp is hygroscopic, meaning it absorbs and releases moisture without losing insulating power. This helps regulate humidity indoors and reduces the risk of mold or mildew—a big plus for humid climates.
Sound Proofing
Thanks to its dense, fibrous structure, hemp insulation also provides excellent sound absorption, making it a great choice for noisy neighborhoods or homes near busy roads.
Hemp Insulation vs. Other Insulation
Hemp vs. Fiberglass Batts
Hemp is safer to install (no itchy fibers) and better at moisture control, but fiberglass is far cheaper. Cost per square foot for fiberglass is $0.30 – $1.50, versus $1.40 – $3.10 for hemp.
Hemp vs. Rigid Foam Board
Rigid foam has a higher R-value per inch and is better for extreme temperatures, but hemp breathes better and is easier to install around wiring and pipes.
Hemp vs. Spray Foam Insulation
Spray foam creates a tighter air seal and has a higher R-value, but it contains harmful chemicals and isn’t biodegradable. Hemp is healthier, more sustainable, and naturally regulates moisture, preventing mold buildup.
Cost Considerations
Hemp insulation costs more than fiberglass but less than spray foam:
- Hemp: $1.40 – $3.10 per square foot
- Fiberglass: $0.30 – $1.50 per square foot
- Spray foam: $1.50 – $3.50 per square foot
As hemp insulation becomes more widely produced, expect to see prices drop.
