Quick answer: Hemp insulation, such as HempWool® batts, is made from industrial hemp fiber and is sold as free of formaldehyde and added VOCs, so it adds very little to your indoor air. It insulates about as well as fiberglass batts and is a good pick for walls and rooflines when you want a low-chemical, renewable material.
What is hemp insulation?
Hemp insulation is a batt or blanket made from the fibers of industrial hemp, a fast-growing plant raised for fiber and seed. And no, it isn’t that kind of hemp. Industrial hemp is a building material here, and the only thing it does to your house is slow down heat and sound.
It fills the same framing cavities as fiberglass or mineral wool, and it’s installed much the same way. The difference is what it’s made of and what it leaves in the air after it goes in.
Why is hemp insulation good for indoor air quality?
Mainly because there’s very little in it to off-gas. Here’s what it brings to a home:
- Low chemical load: Some conventional insulation products and binders can release chemicals into the air, especially when new. Hemp batts like HempWool® are made without formaldehyde or added VOCs, so there’s less “new house smell” drifting out of the walls. If anyone in your home is sensitive to chemical odors, that’s worth knowing.
- Moisture handling: Hemp fiber can absorb moisture and release it again without losing much of its insulating value. That helps buffer small swings in humidity inside a wall. It is not a substitute for controlling humidity, fixing leaks and running a properly sized AC, which are what actually keep mold away in a humid Austin summer.
- Solid thermal performance: Insulation’s main job is slowing heat flow, and hemp does that about as well as common batt products (see the R-value below). In Central Texas that mostly means keeping August heat out of the living space so your AC runs less.
- Sound absorption: The dense fibers soak up sound, so hemp batts help quiet traffic noise outside and a TV in the next room. A home office next to the kids’ bedroom is a good candidate.
- Renewable source: Hemp grows quickly and generally needs little in the way of pesticides or herbicides, and the plant takes up carbon dioxide as it grows. If a lower-impact building material matters to you, it checks that box.
What is HempWool® batt insulation?
HempWool® Batt is a hemp insulation product made as an alternative to traditional fiberglass batts. It’s sized for standard wood and metal framing and uses a friction fit, so it holds itself in wall and roof cavities instead of sagging or settling over time. The manufacturer describes it as VOC-free and non-toxic, treated with a fire retardant, and designed for both thermal and sound insulation.
Where it fits best:
- Exterior and interior wall cavities, and rooflines: anywhere you want both heat control and sound control, such as exterior walls, walls between bedrooms and the underside of a roof deck.
- R-value: HempWool® Batt is rated at R-3.69 per inch, which puts it in the same neighborhood as common fiberglass batts. More R-value per wall means less heat moving through it, which your cooling bill will notice.
Batts need open framing to install, so they make the most sense in new construction, additions and remodels where the walls are already open.
Can you use hemp insulation in attics and existing walls?
Not easily with batts, which is why we’re watching for blown-in hemp insulation to become more widely available. Many Austin-area attics are insulated with blown-in material, and closed walls in an existing home can only be filled by blowing insulation in. A blown-in hemp product would make it practical to use hemp throughout a house, including attics, hard-to-reach spaces and finished walls.
Until then, hemp batts are a good choice for walls and rooflines, and the rest of the house can still be insulated and air sealed well with other materials. The bottom line: if you’re opening walls anyway and want insulation that insulates well, dampens sound and adds very little to your indoor air, hemp deserves a spot on the shortlist.
Related guides: Why Insulation Is Key to a Cleaner, Drier Home in Central Texas, How Insulation Impacts Your HVAC System: Boost Efficiency or Cause Harm? and What Are MERV Ratings, and How Do They Affect IAQ?.
About Gold Eagle Services: This guide comes from the team at Gold Eagle Services, a family-run Austin HVAC, indoor air quality and mold remediation company founded in 2017. We’re licensed (TACLA119235 and RCO1783), insured and bonded, and we serve homes across the greater Austin area.
Need help with this in your home? Learn about our indoor air quality solutions, or call 512-489-4653 to schedule a visit.
