Walls that breathe.
Karu Materials brings hemp-lime block systems to the American Southeast — solid masonry that insulates, regulates moisture, and quiets a room in a single material.
Request specs & pricing →Atlanta, Georgia — now taking project enquiries for 2026–27 builds.
- 7 formatsblock thicknesses from 2.8″ to 12.6″ (70–320 mm)
- R-2.1 / inchthermal conductivity 0.069 W/m·K, tested to EN 12664
- 20 lb/ft³318 kg/m³ — light enough for one person to place by hand
- 3 ingredientshemp hurd, lime, and clay — nothing synthetic
| Block | Thickness | Face | R-value (US) | RSI |
|---|---|---|---|---|
| Infill 70 | 2.8″ (70 mm) | 23.2 × 11.2″ (590 × 285 mm) | R-5.7 | 1.01 |
| Infill 110 | 4.3″ (110 mm) | 23.2 × 11.2″ (590 × 285 mm) | R-9.0 | 1.59 |
| Wall 150 | 5.9″ (150 mm) | 23.2 × 11.2″ (590 × 285 mm) | R-12.3 | 2.17 |
| Wall 200 | 7.9″ (200 mm) | 23.2 × 11.2″ (590 × 285 mm) | R-16.5 | 2.90 |
| Wall 250 | 9.8″ (250 mm) | 23.2 × 11.2″ (590 × 285 mm) | R-20.6 | 3.62 |
| Envelope 285 | 11.2″ (285 mm) | 23.2 × 12.6″ (590 × 320 mm) | R-23.5 | 4.13 |
| Envelope 320 | 12.6″ (320 mm) | 23.2 × 11.2″ (590 × 285 mm) | R-26.3 | 4.64 |
One block, three jobs.
A hemp-lime block is insulation, thermal mass, and wall infill at once. Laid around a timber or steel frame, it forms a monolithic, vapor-open envelope — no cavity, no membranes, no thermal bridging at the joints.
The blocks are non-load-bearing and cut with ordinary hand tools. Walls are finished in lime plaster inside and out, or ventilated cladding.
Why hemp-lime.
A hemp-lime wall is a moisture buffer for the whole house. The blocks are fully vapor-permeable: they take up excess moisture from indoor air and release it again as the air dries, so moisture moves through and out instead of getting trapped behind a membrane or condensing in a cavity. No damp pocket, no hidden condensation plane, no food for mold.
The binder is natural lime and clay — no polymers, no plasticizers, no synthetic resins, which sets these blocks apart from most engineered wall products. Lime keeps the wall naturally alkaline (nothing for mold or insects to live on) and fully mineral, which is why finished hemp-lime walls post exceptional fire results — see the fire performance.
The same porous mass that buffers moisture also absorbs sound: a hemp-lime wall is an acoustic layer as much as a thermal one. And the hemp stores more carbon during growth than block production emits — a bonus that comes with the material, not the reason to choose it.
- Appendix BLhemp-lime construction entered the 2024 International Residential Code
- 2027 IRCfire-rated hemp-lime wall assemblies approved by committee, Oct 2025
- Georgiapermitted today via engineered alternative-means approval — we support the submittal
- Hours, not daysour ready-made submittal pack keeps the engineer’s stamp affordable
A real code path.
Hemp-lime construction is in the 2024 International Residential Code as Appendix BL, and the first US jurisdictions have begun adopting it. Where the appendix isn’t yet adopted — including Georgia — hempcrete homes are permitted through the code’s alternative materials provision with an engineer’s stamp.
Karu Materials was founded by an architect. We come to your project with datasheets, EN test reports, BIM objects, and submittal support — not just pallets.
The engineer’s stamp is usually the line item that scares people off alternative materials — because the engineer is asked to research a material from scratch, on your budget. We remove that cost: every Karu project ships with a pre-assembled submittal pack — EN test reports, typical wall sections, structural frame details, and precedent approvals — so your engineer reviews rather than researches. No engineer yet? We’ll introduce you to structural engineers who already know hemp-lime, and we stay in the submittal with you until the permit is issued.
Straight answers up front: the blocks are non-load-bearing infill around a structural frame. A made-to-order factory shipment runs 8–12 weeks — which is why we’re building stock at the Port of Savannah, so stocked formats deliver across the Southeast in days. Either way, talk to us early in design, not at framing.
One factory, full documentation.
Our blocks are ECOblocos — made by Cânhamor in Alentejo, Portugal, at a purpose-built, solar-powered factory inaugurated in 2025 that processes the raw hemp and presses the blocks on a single site, with hemp grown on the maker’s own regenerating farmland.
Performance is independently lab-tested to EN standards — the same test regime Germany’s building authorities hold materials to. A block engineered to satisfy a German building inspector arrives in Georgia overqualified, and every delivery ships with the manufacturer’s full technical documentation: datasheets, test reports, application manuals, and BIM objects.
- 2025new integrated factory — raw hemp in, finished blocks out
- EN 12664independent lab testing behind every published value
- 0 polymershemp, lime, clay, water — no plasticizers, no synthetic binders
The material in thirty seconds.
See it made.
Grown in regenerating fields, pressed in a purpose-built factory, cured, palletized, and shipped with full technical documentation. Thirty seconds tells the story better than a datasheet — though we have those too.
Straight answers.
Samples. Cut-block sample kits with datasheets ship to serious projects — request a kit with your project type and location.
Details & BIM. Typical wall sections, corner and opening details, foundation course, and BIM objects come from the manufacturer's published construction-detail library — available with every enquiry.
Finishes. Walls take breathable lime plaster or render systems in two to three coats — never cement or acrylic coatings, which trap moisture. We spec the system with you.
Delivery. Pallets will be warehoused with our third-party logistics partner at the Port of Savannah — containers clear customs portside and stocked formats truck anywhere in the Southeast in days, not the weeks of a drop-shipped overseas order. Sample stock sits in Atlanta.
Services. Electrical and plumbing run in chases cut directly into the block with hand tools, or in a battened service cavity on the interior face — both standard hemp-lime practice.
Warranty. Blocks carry the manufacturer’s product warranty with EN-tested performance documentation, and our submittal support stands behind every specification.
Pricing. Pallet and project pricing on request — indicative budgets shared at the first call, firm quotes with format mix and delivery. First Southeast installations are planned for 2026–27; early projects get founding-project attention.
Healthy by nature.
Most wall systems trade indoor air quality for insulation values — foams, films, and adhesives that keep off-gassing into the rooms where your family sleeps. Hemp-lime doesn’t make that trade. Three natural ingredients — hemp hurd, lime, and clay: no VOCs, no formaldehyde, no synthetic binders — nothing to off-gas, on day one or in year twenty.
And because lime keeps the wall naturally alkaline, mold has nothing to live on; because the wall is vapor-open, moisture moves through and out instead of getting trapped where you can’t see it. Healthy isn’t a coating we add — it’s what the material is.
It’s why the healthy-home movement keeps arriving at hemp-lime from every direction — building biologists, allergy-conscious parents, architects who’ve read one too many material safety data sheets. The wall your family lives inside shouldn’t need one.
- Nothing to off-gas. No foams, films, glues, or flame-retardant chemistry — the wall adds nothing to your indoor air, ever.
- Nothing for mold. Lime’s natural alkalinity means no food source and no damp pockets — the conditions mold needs never form.
- Humidity, buffered. Vapor-open walls absorb moisture spikes — Georgia summers included — and release them dry, easing the load on your HVAC and your lungs.
- No fibers, no dust. Nothing itchy to install, nothing airborne to live with — a difference every fiberglass-insulated attic makes obvious.
- Quiet, stable rooms. Porous bio-based mass absorbs sound and holds temperature steady — the stuff of sleep.
Building in the Southeast? Let’s talk early.
Specification advice, samples, and pallet pricing for architects, builders, and owner-builders. Every enquiry gets datasheets, wall details, and a straight answer on budget and lead time.
rachel@karumaterials.com →