Gaia™ Building Systems
GaiaCast™ Cast-in-Place Hempcrete / Hemp-Lime Walls
Cast-in-place hemp-lime construction for monolithic wall infill and project-specific healthy-building assemblies.
What Is GaiaCast™?
GaiaCast™ is the cast-in-place hempcrete / hemp-lime application within Gaia™ Building Systems, designed for monolithic wall infill and project-specific construction assemblies. It uses the same hemp hurd and mineral lime material family as GaiaCrete™ hemp-lime building material, placed wet and cured in position.
The result is a continuous wall infill with no component joints — the approach many designers prefer when they want the wall to read as one seamless mass.
How the Wall System Works
The structural frame goes up first. Temporary forms are set against the framing, the damp hemp-lime mix is placed and tamped in lifts, and the forms move up the wall as the work progresses. Once the forms come off, the wall cures and is finished with breathable plasters or claddings.
Because the material is placed around the frame, the infill can follow irregular geometry, wrap framing members, and close gaps that a component product would leave. Bulk-water management and a vapor-open finish remain essential to the assembly's long-term performance.
Existing homes
Cast work suits renovations where framing is already opened up — gut rehabs, wall reconstruction, and deep-energy retrofits. See retrofit and rehab for how these projects are scoped. Where walls stay closed, GaiaBloc™ hemp-lime building blocks are usually more practical.
New construction
On new builds the frame and forms are sequenced together, which works well for continuous wall assemblies in hempcrete house plans and healthy new-home designs.
Discuss Your Project
Pricing is project-specific and depends on product format, quantity, shipping distance, wall assembly, project location, installation requirements, and current availability.
Contact Mr Hemp House® for current product, dealer, consultation, shipping, and installation availability. Availability varies by market.
Building-Science Characteristics of Hemp-Lime
These characteristics describe hemp-lime construction as a category. Product-specific and assembly-specific performance is governed by current technical documentation.
Vapor permeability & moisture buffering
Hemp-lime materials can adsorb and release moisture as indoor conditions change, helping moderate short-term humidity swings when incorporated into a properly designed vapor-open assembly.
Mold-resistant characteristics
The high-alkalinity mineral composition of hemp-lime is inhospitable to fungal growth, and the material is vapor-permeable rather than moisture-trapping. Actual mold risk depends on moisture exposure, assembly design, workmanship, bulk-water management, ventilation, and maintenance.
Fire performance
Hemp-lime materials are known for favorable fire-performance characteristics; product- and assembly-specific performance is governed by applicable technical documentation. A Class A flame spread rating (ASTM E84) has been documented for the tested GaiaCrete™ material sample and is not translated here into an hourly fire-resistance rating.
Acoustic characteristics
Hemp-lime's porous structure can help dampen sound and contribute to quieter wall assemblies. Exact acoustic performance depends on wall thickness, finishes, framing, and complete assembly design.
Thermal characteristics
Hemp-lime contributes both insulation and thermal mass to the wall assembly. Thermal performance varies by formulation, density, thickness, moisture content, finishes, and complete wall assembly.
Biogenic carbon storage
Hemp absorbs atmospheric carbon while growing, and hemp-based materials can retain that biogenic carbon in the building. Lime binders also carbonate during curing. Product-specific lifecycle figures are not published as a single number.
Pest considerations
The mineral-rich hemp-lime matrix is generally less attractive as a food source than untreated wood-based materials. Pest performance depends on assembly details, site conditions, and construction.
Long-life assemblies
Published hemp-lime lifecycle research has cited expected service-life assumptions exceeding 100 years for properly designed, constructed, protected, and maintained wall assemblies. This is category-level hemp-lime research, not a Gaia™ product warranty.
The 2024 IRC includes Appendix BL for hemp-lime construction. Local code adoption, engineering, design, product documentation, and authority-having-jurisdiction requirements govern each project.
Technical Information
Technical specifications are being finalized. Contact Mr Hemp House® for current project documentation and product availability.
Cast density, thickness schedules, R-values, acoustic ratings, compressive values, fire-resistance ratings, cure times, and installed cost are not published for GaiaCast™. Documented GaiaCrete™ material test results are not automatically transferred to a specific cast assembly.
Comparing the Gaia™ Building Systems Formats
GaiaCast™ trades component convenience for a continuous, monolithic wall. The other formats trade continuity for staging, speed, or prefabrication.
| Feature | GaiaCrete™ | GaiaBloc™ | GaiaPanel™ | GaiaCast™ |
|---|---|---|---|---|
| Format | Hemp-lime material (sprayed or poured) | Pre-formed block | Panelized wall system | Cast-in-place infill |
| Primary application | Wall, attic, and envelope applications | Wall infill and retrofit build-out | Repeatable wall assemblies | Monolithic framed-wall infill |
| Installation approach | Trained crew, project-specific method | Stacked and fitted by hand | Fabricated off-site, set on-site | Formed and cast in place |
| Existing homes | Project-dependent | Often a good fit where access is limited | Best suited to additions and rebuilt walls | Suitable where framing is opened up |
| New construction | Yes, with a designed assembly | Yes | Yes — schedule-driven projects | Yes — continuous wall assemblies |
| Prefabrication level | None — mixed and applied on-site | Component-level | Highest | None — formed on-site |
| Wall integration | Around a structural frame | Fitted within or against framing | Framing and infill delivered together | Continuous infill around framing |
| Best project fit | Custom hemp-lime applications | Retrofits and phased work | Repeatable plans and tight schedules | Seamless, monolithic wall design |
| Technical documentation | Available — see technical resources | In progress — request current documentation | In progress — request current documentation | In progress — request current documentation |
Final product selection depends on project design, engineering, code requirements, climate, availability, and installation method.
For Builders, Architects, and Remodelers
Cast work is crew-dependent: mix consistency, lift height, tamping, form sequencing, and drying conditions all affect the finished wall. Design coordination covers wall thickness, framing layout, finish compatibility, and documentation for the authority having jurisdiction. Contractors can review the contractor pathway or the Mr Hemp House® dealer program.
Technical Documentation & Research
Mr Hemp House® separates evidence into levels so builders, designers, and homeowners can see exactly what a given statement is based on.
- Product-specific testing — laboratory results for that exact Gaia™ product, where available.
- Assembly-specific testing — results for a tested wall, panel, or installation assembly.
- Hemp-lime category research — published findings that apply to hemp-lime construction generally, not to a specific Gaia™ product.
- Manufacturer / internal documentation — technical documents produced by Mr Hemp House® and identified as such.
Category-level hempcrete research does not by itself demonstrate GaiaBloc™, GaiaPanel™, or GaiaCast™ performance. Review the current documentation set on technical data & resources.
Explore Gaia™ Building Systems
One hemp-lime material family, four ways to build with it.
Hemp-lime material system
GaiaCrete™ hemp-lime building material
The core hempcrete / hemp-lime building material behind every Gaia™ format — used for sprayed, poured, and cast wall applications.
Pre-formed block
GaiaBloc™ hemp-lime building blocks
Pre-formed hemp-lime blocks that bring hempcrete into a repeatable, stackable format for retrofit and new-construction wall infill.
Panelized wall system
GaiaPanel™ hemp-lime wall panels
Panelized hemp-lime wall assemblies fabricated off-site to bring bio-based wall construction into a faster, repeatable format.
GaiaCast™ FAQs
GaiaCast™ is the cast-in-place hempcrete / hemp-lime application within Gaia™ Building Systems, designed for monolithic wall infill and project-specific construction assemblies. The material is mixed and placed into forms or a framed cavity on site, then cures in place.
Call for Pricing
Pricing is project-specific and depends on product format, quantity, shipping distance, wall assembly, project location, installation requirements, and current availability.
Contact Mr Hemp House® for current product, dealer, consultation, shipping, and installation availability. Availability varies by market.
More on the product family: Gaia™ Building Systems.