Hempcrete & Hemp Building Materials: Code Approvals, Real Projects, Where to Buy

Hempcrete & Hemp Building Materials: Code Approvals, Real Projects, Where to Buy

For 25 years, the conversation about hempcrete in the United States went something like: "It's amazing — fireproof, insulating, mold-resistant, carbon-negative — but you can't legally build with it." That conversation ended in 2023 when hempcrete was added to the 2024 International Residential Code. As of mid-2025, two US jurisdictions (Austin, Texas and the State of Minnesota) have formally adopted the appendix and unlocked permitted hempcrete residential construction. This is the 2026 status report on hempcrete — what's approved, where it's being used, who's shipping the material, and what's still pending.

What HempCrete actually is?

Hempcrete is not concrete. It's a bio-composite made from three ingredients: hemp hurd (the woody inner core of the hemp stalk), a lime-based binder, and water. Mixed together and cast or sprayed in place, it cures into a lightweight, breathable, insulating wall material with thermal performance roughly comparable to fiberglass batt and significantly better moisture and air-quality behavior.

Hempcrete is not load-bearing. It's an infill — used to fill the wall cavity around a structural frame (usually timber or steel). Think of it as a structural insulation material rather than a structural material itself. This distinction matters because it determines how hempcrete is permitted under building codes.

The 2024 IRC approval, in plain English

Hempcrete appears as "Appendix BA" (sometimes referenced as Appendix BL in updated drafts) in the 2024 International Residential Code, which was published in 2023 by the International Code Council. The IRC governs one- and two-family dwellings and townhouses in the US.

What that means: hempcrete is now a code-recognized material for residential construction under the IRC. Builders can specify hempcrete in their plans, building inspectors have a code reference to evaluate it against, and homeowners can get permits for hempcrete construction in jurisdictions that have adopted the appendix.

The fine print:

  • Appendices in the IRC are voluntary. They must be specifically adopted by a state or local jurisdiction to become enforceable in that area.
  • Even where not officially adopted, builders can petition local officials to allow hempcrete construction on a project basis, using Appendix BA as the technical reference.
  • The approval applies to hempcrete as non-structural wall infill only, similar to straw bale and cob construction.
  • In low-seismic regions, hempcrete can be used prescriptively without engineering. In high-seismic regions, an engineered design is required.

Where hempcrete is permitted as of 2026

As of the most recent code adoption tracking:

  • City of Austin, Texas — formally adopted the 2024 IRC Appendix BA effective July 10, 2025. First US jurisdiction to do so.
  • State of Minnesota — adopted shortly after Austin in 2025. Statewide.
  • Other jurisdictions — increasing number of cities and counties evaluating adoption; builders in many areas can pursue project-by-project permits using the IRC appendix as reference.

The pattern: states and cities that have active sustainable-building initiatives, recent code adoption cycles, or strong builder demand are leading the adoption curve. Expect 5-10 more jurisdictions to adopt by end of 2026 based on current activity.

What's pending: commercial approval

For hempcrete to be approved for commercial buildings — schools, office buildings, multi-family above 3 stories, retail — it needs to be added to the International Building Code (IBC), the model code that governs non-residential construction. The IBC operates on a 3-year cycle and is currently open for submissions in the 2025-2026 cycle. The hempcrete advocacy community is actively pursuing IBC inclusion in this cycle.

An update to Appendix BL in the IRC was also approved by the IRC Committee on October 22, 2025 in Cleveland, with potential resubmission planned for the Spring 2026 final public comment hearing. The trajectory is positive but not yet complete.

The performance case: why builders care

Beyond regulatory novelty, hempcrete delivers genuine performance benefits that conventional construction struggles to match:

Thermal performance

Hempcrete walls typically deliver an R-value of approximately R-2.5 to R-3 per inch of thickness — comparable to fiberglass batt. A 12-inch hempcrete wall therefore delivers approximately R-30 to R-36, exceeding most code minimums for residential walls in most climate zones.

More importantly, hempcrete's thermal mass behavior is significantly better than fiberglass. The wall material itself stores and releases heat, smoothing daily temperature swings inside the building. Real-world energy use in hempcrete homes is often 30-50% lower than in equivalent stick-framed homes, even when the calculated R-values are similar.

Moisture management

This is hempcrete's killer feature. The wall is breathable — water vapor can pass through it — but the lime binder keeps liquid water out. This means hempcrete walls don't trap moisture the way most insulated wall systems do, which means no mold, no rot, no vapor barrier failures.

For climates with high humidity or significant temperature swings, this is a major durability advantage.

Fire resistance

Hempcrete is essentially fireproof at the wall-assembly level. The lime binder doesn't burn, and the hemp hurd inside the matrix is encased in lime and doesn't have enough oxygen exposure to sustain combustion. Hempcrete walls have been tested at multiple-hour fire ratings.

Pest resistance

Termites don't eat lime. Rodents don't burrow into hempcrete. The wall doesn't provide the food source or habitat that wood framing and many insulation materials do.

Carbon negative

This is hempcrete's biggest sustainability claim, and it's true: a hempcrete wall sequesters more carbon than it emits in production. Hemp absorbs CO2 as it grows; that carbon stays locked in the wall for the life of the building. Estimates put hempcrete at roughly -50 to -150 kg CO2 per cubic meter of wall, depending on production method and hemp source.

For comparison, conventional concrete is approximately +400 kg CO2 per cubic meter. The difference is substantial when scaled across an entire building.

The constraints, honestly stated

Hempcrete is not a drop-in replacement for stick framing. The constraints to understand:

  1. It's slower to build with. Hempcrete is cast or sprayed in place around the structural frame. The drying/curing process takes weeks (faster with sprayed installation, slower with cast). Standard construction schedules need to be extended.
  2. Wall thickness is greater. A code-compliant hempcrete wall is typically 10-14 inches thick. That reduces interior floor area compared to a 4-6 inch insulated stud wall.
  3. Labor is specialized. Not every construction crew knows hempcrete techniques. The pool of qualified installers is growing but still small.
  4. Cost premium of 10-30% over conventional construction in most US markets, though this varies significantly by region and project specifics.
  5. Material supply chain is still maturing. Hemp hurd at construction quantities requires sourcing from specialized suppliers. Lime binders for hempcrete (typically natural hydraulic lime) often need to be imported or sourced from a small number of US producers.

Where to buy hempcrete materials in the US

The North American hempcrete supply chain includes:

  • Hempitecture (Idaho) — full-stack hempcrete supplier including HempWool insulation product
  • Hempcrete Direct — pre-mixed hempcrete kits and component sourcing
  • Just BioFiber (Canada) — modular hempcrete blocks for prefab application
  • HempStone — hempcrete and hemp-lime construction materials and consulting
  • Dominion Hemp (Virginia) — hemp hurd supplier including building-grade material
  • US Hemp Hurd — bulk hemp hurd supply for hempcrete production

For specialized lime binders, US Heritage Group, Ecologic Brands, and several European importers serve the construction market.

The 2026 outlook

The next 24-36 months are the inflection point for US hempcrete. Three things are likely to happen in that window:

  1. More jurisdictions adopt the IRC appendix. Expect another 10-20 cities and 5-8 additional states by end of 2027.
  2. IBC commercial approval moves forward. Whether the current cycle succeeds or the next one does, commercial hempcrete approval is a question of when, not if.
  3. Supply chain consolidates. Several hempcrete-specific manufacturers will reach the scale required to offer competitive pricing against conventional materials in regional markets.

The builders and developers getting hempcrete projects through permits and into the ground in 2026-2027 will have the operational experience and supplier relationships to dominate the category as it scales in the late 2020s.

The bottom line

Hempcrete is no longer a fringe building material. It's code-recognized for US residential construction, formally adopted in a growing list of jurisdictions, and supported by a North American supply chain that's small but professional. For builders interested in high-performance, low-carbon residential construction, hempcrete in 2026 is a realistic specification to put on a real project.

The commercial side will follow within the next code cycle. By 2030, hempcrete is likely to be a routine option in sustainable construction across most of the US.

AllHemp.com curates hemp building materials from vetted suppliers including hempcrete components and hemp insulation products. For broader industrial hemp context, see our pieces on the 2026 industrial hemp market, hemp plastics manufacturers, and hemp fiber and hurds wholesale sourcing.

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