BuildersllC
Rondout
Natural
Explore New Paradigms
Materials & Methods
Our Objective to use natural and local materials and establish regenerative bio-material resources in our built environment is a central value in our building practice. Wood, Hemp, lime, and clay naturally regulates humidity levels, preventing the growth of mold and mildew. Additionally, the absence of toxic substances commonly found in conventional building materials enhances indoor air quality, promoting the well-being of the home's occupants and contribute to a healthier indoor environment. Working with natures biology and minimally processed earthen materials is the priority over high tech manufactured and imported products.
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Building Envelope Failures
Many post-war homes were built without understanding of moisture dynamics, leading to poor ventilation, mold and rot behind vapor barriers leading to inadequate insulation performance over time.
Traditional Vernacular Construction is Built to Last
Vernacular homes are adapted to the local climate (e.g., thick adobe in hot regions, stone or Lime in wet ones). Built with natural materials like earth, timber, lime, or stone, these materials can be repaired and maintained rather than replaced, where more conventional manufactured systems often degrade and are difficult to maintain as the components become outdated. Vernacular homes are designed to age gracefully, not fight nature.
Vernacular building systems may last centuries—not decades—and can be deconstructed or repaired with minimal input of hand tool, skilled labor and localized resources. Many homes built post-WWII are reaching the end of their lifespan. Homeowners face costly repairs, energy inefficiencies, and vulnerability to climate extremes.
The Post-WWII Housing Boom & Decline in Durability
After WWII, a huge demand for housing emerged—driven by returning veterans, suburban expansion, and the Baby Boom. Builders responded with faster, cheaper methods. Here’s how and why quality started to degrade:
Material Degradation
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Old Growth vs. Fast-Growth Lumber: Pre-WWII homes often used dense, old-growth wood with natural durability. Post-war homes shifted to fast-grown, younger trees—softer, weaker, and more susceptible to rot and pests.
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Synthetic & Disposable Materials: More plastics, OSB, MDF, vinyl, and petrochemical-based products replaced natural, durable materials like solid wood, stone, or lime plaster.
Design Life & Planned Obsolescence
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Modern stick-frame homes are often designed for a 30–50 year lifespan, not for centuries like vernacular or timber-framed structures.
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Code Minimums replaced craft—builders do what’s required to pass inspection, not necessarily what’s best for long-term performance.
Craftsmanship vs. Mass Production
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Traditional Buildings (vernacular, timber frame, adobe, etc.) were built with local materials and climate knowledge—by hand, with joinery, and skills passed down generations.
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Post-war homes were mass-produced using tract housing techniques—assembly-line style—with minimal individual attention to detail or site conditions.​​
The building industry is undergoing a slow but meaningful transformation in response to environmental pressures, health concerns, resource scarcity, and climate change. There is increasing momentum behind a shift away from fossil fuel–derived, highly processed materials (e.g., rigid foams, vinyls, synthetic resins) toward natural, renewable, and carbon-sequestering alternatives like earthen and bio-based materials.
Here’s a breakdown of how the industry is adapting, and where it’s headed:
Key Drivers of Change
Climate Change & Carbon Accounting
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Buildings are responsible for 39% of global COâ‚‚ emissions (operational + embodied carbon).
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There's a growing push to reduce embodied carbon, i.e., the emissions from material production and construction.
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This favors low-energy materials like hempcrete, straw bale, earthen plaster, and mass timber.
Health & Indoor Air Quality
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Concerns about VOCs, formaldehyde, and mold in modern buildings are increasing demand for non-toxic, breathable materials like clay, lime, and wood.
Circular Economy & Waste Reduction
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Materials that can be reused, composted, or reintegrated into the earth (e.g., mycelium, earth blocks) align with circular economy goals.
Code & Policy Changes
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New ICC codes are slowly legitimizing natural materials
(e.g., Appendix U for Cobb, Appendix BL for Hemp/Lime (Hempcrete) Insulation, Appendix R for Light Clay Straw Insulation, Appendix S for Strawbale Insulation, Appendix Q for Tiny Home Construction, . -
Cities and states are adopting low-carbon material procurement policies.
Consumer Awareness & Market Demand
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Homeowners, particularly millennials and Gen Z, are seeking sustainable homes with lower energy bills, healthier interiors, and climate resilience.
The Rise of Earthen & Bio-Based Materials
Examples of materials gaining traction:
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Hempcrete: Carbon-sequestering, vapor-permeable, fire-resistant
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Straw bale: High insulation, locally available, low embodied energy
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Clay and lime plasters: Breathable, non-toxic, regulate humidity
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Mass timber - Renewable, stores carbon, replaces concrete/steel
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Mycelium composites: Used for insulation and non-structural panels
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Wood fiberboard & cellulose: Insulation made from waste wood or recycled paper
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Compressed Earth Blocks (CEBs) and rammed earth: Durable, low energy, local soil-based
Trends in the Construction & Housing Market
Prefabrication of Natural Components
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Panelized hempcrete, straw bale SIPs, and prefabricated mass timber systems are helping natural materials enter the mainstream by lowering labor costs and simplifying code compliance.
Institutional Adoption
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Commercial-scale projects (like schools and offices) are beginning to specify low-carbon materials.
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Universities and public buildings are experimenting with bio-based insulation, lime plaster, and mass timber.
Regenerative Building Approaches
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Moving beyond “sustainability” toward regenerative design: buildings that restore ecosystems, sequester carbon, and support local economies.
Where the Market is Headed
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2025–2030: Rapid growth in carbon accounting, embodied carbon disclosure, and use of natural insulation materials (especially in Europe and parts of the U.S. West and Northeast).
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2030–2040: Mainstreaming of carbon-storing construction, potentially driven by policy (e.g., carbon taxes, green building mandates).
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Construction Tech: Continued emergence of bio-fabrication, 3D printing with earthen materials, and digital design tools supporting climate-conscious design.
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Market Shift: Natural materials still niche (<5% of market), but poised for double-digit growth annually, especially in retrofit and small-scale residential.
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In Summary:
The building industry is gradually evolving toward a post-petroleum architecture, where natural, low-carbon, and health-promoting materials are increasingly prioritized. Although traditional construction still dominates, policy shifts, climate urgency, and consumer demand are carving space for a regenerative, bio-based building future.
BUILDING COMPONENTS
Hempcrete
Hempcrete is a bio-composite made of the inner-woody-core of the hemp plant mixed with a lime-based binder. Hemp cores are called Shivs or Hurds and have a high silica content, which allows it to bind well with lime. The result is a lightweight cementitious and insulating material. A fully cured hempcrete block can actually float in a bucket of water. Although hempcrete application and methods are evolving, it is not currently used as a structural element, only as insulating infill between the frame members though it does tend to reduce racking. The structural loads are still carried by internal framing.
There are a few different applications - panelized, block based, and spray. There are also other hemp/ Bio Fiber batt insulation, hemp wool, etc. The performance, I've been told by an installer that they were able to achieve a panelized hempcrete wall system with an R-30 at 10.5 inches.
The ecological and agricultural benefits of hemp as a raw material (legalized by the 2018 farm bill in the US). Lots to say there. Beyond that, its grow cycle is nuts - a tree takes up to 28 years to become a usable construction product, whereas hemp can take as little as 6 months to become a usable construction product. The curative process is also a carbon sequestration process. All around a fascinating product.
Hempcrete Insulation
The Hempcrete insulation material composed of hemp hurd coated in a hydraulic lime binder. This material blown into wall cavities with Ereasy spray application system at a density < 200 kg/m. Once dry, the insulation is coated with a two-coat lime plaster as a finish. Several tests for the R-value of plastered hempcrete walls with a density in the range of 200 kg/m have been conducted with a range of results from 0.06- 0.08 w/mK (R-1.8 to 2.4 per inch) The steady-state R-value performance of hempcrete insulation has been shown to highly underestimate the in-situ performance of the insulation. The unique hygrothermal properties of the insulation result in a level of actual performance that is up to 45% better than insulation materials with comparable steady-state R-values. Hempcrete has two components to provide air tightness. The insulation material itself provides an exception degree of air control, with one test building exhibiting less than 0.6 ACH/50 without any additional air control layer. The continuous plaster skin applied directly to the hempcrete insulation, along with taping of seams at ceiling, floor and penetrations, can similarly provide air control that exceeds code requirements. Hempcrete insulation contains no toxins and does not off gas. The lime binder and lime plaster are inherently anti-microbial and anti-fungal due to their high PH levels and is a natural fungicide preventing mold growth. Hempcrete insulation stores more atmospheric carbon in the hemp hurd material than is emitted during the harvesting and production of the ingredients, making it a net-negative carbon material that is a climate change draw down rather than a net emitter of GHGs. Hempcrete insulation is straightforward to remove from wall cavities, and can be 100% recycled back into new insulation. A building with hempcrete walls will be straightforward to renovate and modify with little or no waste or damage to structural components.
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Humidity Control / Moisture Management
Humidity control of hempcrete insulation is one of the most advantageous elements of this material when compared to other insulation products. Hempcrete is vapor permeable which allows vapor to diffuse through it & increases the drying potential of the building envelope. In addition, Hempcrete is able to absorb up to 20% of its weight in water before losing its insulating values. This results in better thermal performance in your structures while also minimizing the risk of mold developing from moisture related issues.
Thermal Inertia or Phase Shift
Thermal inertia is the ability of a material to store heat or cold. The more dense a material is, the higher its thermal absorption capacity. Cast in place hempcrete is a relatively dense material & therefore has a higher inertia than other conventional insulation materials. Hempcrete should be thought of as a system, not a product. It is a wholistic approach to building a thermal envelope.
Closely related to thermal inertia, is the phase shift capacity of a material. This determines the temperature fluctuations in a building, from external temperature fluctuations. Hempcrete has a significant impact on maintaing a stable indoor temperature, despite external temperature fluctuation. This results in a reduction of heating costs in cooler seasons & climates, but also air conditioning, in warmer weather.
Hempcrete, as a biobased, thermally insulating wall system, produces and displaces multiple materials in one. In summary, the use of hempcrete eliminates the need for drywall, it serves as the thermal insulation, and eliminates all thermal bridging in the envelope. This is because cast in place hempcrete encapsulates structural members. This encapsulation also protects wood
based structural framing materials. Beyond producing multiple materials in one, additional benefits include being better protected against common pests & rodents, preserving the efficiency of the thermal envelope & structural integrity.
Hempcrete is naturally sound absorbing. It increases interior acoustic comfort, while also achieving thermal comfort. By achieving both factors of comfort with a single material, the resulting enclosed thermal envelope offers a multitude of benefits. Hempcrete is not new across the world. It is however a newer building approach in the United States. This means that most contractors are generally unfamiliar with the nuances of installing hempcrete. Despite that, it is a novel approach to building homes that will last over 100 years. Industrial hemp contributes to soil regeneration & requires little water, fertilizer or pesticides.
During it’s growth, industrial hemp is estimated to absorb 9.8 tons of co2 per acre, thus reducing the carbon footprint of hempcrete & the structures that use it. Additionally, the limestone based binder will calcify over time, actively pulling carbon dioxide out of the atmosphere until the wall is fully cured.
Made 100% of natural biobased materials, hempcrete is a healthy building approach because it contains no VOC’s (Volatile Organic Compounds) and is red-list ingredient free.
Straw Bale
Ecological
Enough straw is produced in North America to satisfy all of our residential building needs. Straw offers an alternative and sustainable means to house our growing population while diminishing our impact on forests.
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Energy Efficient
Testing has shown the insulating performance of straw bale walls to be between R35 and R50, or roughly twice to three times the real life performance of typical frame wall systems. This significantly reduces heating and cooling bills and the life-cycle cost of a straw bale home.
Affordable
Sourcing biologically based local materials means eliminating the middle man and and the expense the fossil fuel highly mechanized global Economy is . investing in natural building means more of your dollar can be spent on craftmenship towards buildings that will last many lifetimes
Healthy
Organically grown straw and earthen clay or lime based plasters provide a potential solution for the health-threatening paints, glues and toxins embedded in manufactured building materials. Straw bale homes have been built and praised by asthma and allergy sufferers and individuals with acute environmental sensitivities.
Although you may not smell, see or taste it, construction materials emit various gasses and other compounds into our homes, many of which are highly toxic. This is part of the reason why the Environmental Protection Agency says that indoor air can be two to five times (and even up to 100 times) more polluted than outdoor air. Considering Americans on average spend 90% of there lives indoors, having a healthy space is an essential ingredient in cultivating good health. Natural Building emphasizes healthy material selection and is a primary consideration when designing our spaces.
Hands On
Straw bale building permits the average person to actively take part in creating their home and incorporating their own ideas and values into the process. A large number of women are managing their own straw bale projects. It’s proving to be an equal opportunity material!
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Architectural beauty
Straw bale building is easily adapted to suit traditional designs. It also allows for new and creative custom designs. Sweeping curves, rounded edges, deep sills and built-in window benches are just some of the features commonly seen in straw bale homes. It makes for a unique aesthetic to every building.
Breathability in Construction
This is sometimes confused with air permeability, but it’s important to appreciate that breathability and air permeability are two entirely separate things. As noted above, breathability is the result of a complex interaction between vapour permeability, hygroscopicity and capillarity. Air permeability, on the other hand, is the uncontrolled passage of air through joints and gaps – i.e. leakage. Standards of air leakage in new buildings are carefully regulated and tested, as they should be, since poor air tightness can lead to a significant drop in thermal efficiency.
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Surprisingly, given its importance, breathability is largely ignored by building codes and regulations across the globe. But perhaps this is not altogether surprising, since the market for thermal insulation is dominated (at over 98% of sales) by mineral wool and foamed plastic insulation products, which have very poor hygroscopicity and capillarity. To get around this, the thermal envelopes of new buildings are often specified to include a vapour barrier, which stops any breathability whatsoever, but creates other problems.
Our system made possible by the use of Hempsil and other hygroscopic natural materials. But why is a demountable, breathable thermal envelope better than the alternatives?
“Breathability in buildings is not really about air. It is about water: water as a gas and water as a liquid; water inside the building, water outside the building, and water in the walls, floors and roofs themselves (though not about water in pipes!). It is not only about how water moves through structures (water vapour permeability), but also about the ability of materials to absorb and release water as vapour (hygroscopicity) and about the ability of materials to absorb and release water as liquid (capillarity). Water affects everything in building from the health or decay of building fabric, through to the thermal performance of the building and to the health of occupants. Particularly as we try to increase the airtightness, thermal performance and indoor air quality of our buildings, breathability has become a critical issue, affecting all areas both of new build and of renovation.”
— NEIL MAY, 'BREATHABILITY: THE KEY TO BUILDING PERFORMANCE
Durability
“Except for structural errors, about 90 percent of all building construction problems are associated with water in some way.”
— ASTM E 241-77, RECOMMENDED PRACTICES FOR INCREASING DURABILITY OF BUILDING CONSTRUCTIONS AGAINST WATER-INDUCED DAMAGE.
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Biogenic construction materials are intentionally biodegradable, but this is not the same as lacking durability or longevity. Indeed, cellulose based natural materials such as timber and hemp shiv have a service life measured in centuries, providing the moisture content of the material is maintained at less than 20%.
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The problem with a vapour ‘closed’ thermal envelope, is that a vapour barrier is required on the ‘warm’ side of the wall or ceiling. While this approach is usually (but not always!) effective when the building is new, over time the membrane can easily become damaged, through alterations to the electrics and plumbing, or by simply hammering a nail in to hang a picture. Once damaged, water vapour condenses onto cold surfaces within the fabric of the wall or roof, causing loss of thermal performance, decay and mould, which is harmful to the building and its occupants.
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Other water related problems arise from rain penetration. In conventional construction there are typically two ways of preventing this; either by means of capillary closed finishes (such as render and paint systems), or by allowing outward facing materials to absorb and desorb moisture in cycles. The problem with the former approach is that it is highly susceptible to defects (such as cracking over time) and poor detailing. The latter only works well if the thermal envelope has good breathability, which as noted is not easily achieved with the majority of insulation materials.
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We use a demountable ventilated rain screen cladding system which protects the thermal envelope from water ingress while allowing it to breathe. This ensures that even in extreme weather conditions, the materials within the wall always remain at below 20% moisture content.
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The control of moisture is central to how our system maintains stable indoor temperatures and comfortable levels of humidity. Successive layers of Hempsil and other natural fibre insulations allow water vapour to diffuse through the wall or roof build up and condense (at a microscopic level) within the pores of the material. In severe cold weather the dew point temperature of the interior air (within the thermal envelope) is always below that of the structural elements by virtue of the graduated layers of hygroscopic insulation. Moreover, the capillarity of the natural insulation acts to wick moisture away from the structure.
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Air Quality
The remarkable ability of hemp to passively regulate indoor levels of humidity to between 40-60% relative humidity has been shown to inhibit the spread of viral and bacterial infections. It does this by absorbing moisture into the material during times of high relative humidity and then releasing it again when the humidity drops, which means that condensation cannot form on interior surfaces, for example during cooking, or at night from occupants breathing. Without moisture, bacteria and mould cannot form, greatly improving air quality. By avoiding petrochemical derived building products and utilising only plant-based materials, our system removes the risk posed by a proliferation of harmful chemicals found in many modern construction products.
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​​​Instead of using harmful preservatives, you can choose hardier woods (such as cedar, Black Locust, White oak) that don’t weather as easily and have your wood surfaces sealed with a simple water repellent. If you do use treated wood ensure that the wood you use is arsenic free. The supplier selling you your wood should know about the processes used to treat if. If they don’t then the probably aren’t too concerned about best practices being followed. Find a supplier who knows where your wood comes from and how it’s treated.
