How Is Hempcrete Used In Construction?

How Is Hempcrete Used In Construction
Moreover, hempcrete can be used in combination with other building materials to form both floors and roofs, providing an insulating layer. of concrete. Hempcrete can be used to construct walls, floors and roofs; or molded (monolithic), sprayed or precast (e.g. hemp bricks or panels)4.

How do you cast Hempcrete?

Scoop hempcrete into the casting chamber with your hands, and tamp with your fingers or a blunt tool. Compaction is key. Use your fingers to work the hempcrete, especially around edges, corners, and insertions. Work one layer at a time, in 1′ – 2′ layers.

Can hempcrete be load bearing?

Are hemp blocks load-bearing? – No, hemp blocks are not load-bearing*. They must be associated with a supporting structure. Several construction systems can be considered: the Hempro system, wooden frame, post-beam system, or supporting masonry, * However, it is self-supporting up to 10 metres high depending on its thickness.

What happens if hempcrete catches fire?

What Happens If Hempcrete Catches Fire? How Is Hempcrete Used In Construction Flat House / Practice Architecture + Material Cultures. Image © Oskar Proctor Every time we publish an article about Hempcrete, we get a lot of comments on social media – with a certain level of irony – about what would happen if the material caught fire.

This is actually a legitimate question, as there is still a lot of confusion about the differences between marijuana and hemp, both of which come from the same plant species ( Cannabis Sativa ). But while marijuana has psychoactive effects due to tetrahydrocannabinol (THC), mainly present in the flowers of the plant, hemp-based building materials are produced from its stem, which contains small amounts of THC.

To quickly answer the title question: no, the building won’t be destroyed in the event of a fire. In fact, some tests have shown that these materials have excellent behavior against fire, dissipate flames, maintain structural integrity, and don’t emit toxic smoke.

  • The use of hemp in civil construction is a fairly old practice and several studies have shown how beneficial this plant can be for the future of the industry.
  • It is a material with a negative carbon footprint, meaning that it absorbs more carbon than it emits in its production and, at the end of its useful life, it can be returned to the environment, degrading naturally.

In concrete mixers, hemp, powdered limestone and water are mixed to obtain a thick paste, which through chemical reactions petrifies and becomes a light but very resistant block. For wall construction, the mix can be laid out as non-structural blocks, sprayed, or poured into linear shapes, in the same way as mud walls. How Is Hempcrete Used In Construction Cortesia de BC architects Unlike what you might imagine, hemp-based materials work very well when exposed to fire. In order to measure the characteristics of each material, tests are carried out following specific rules. In the United States, for example, ASTM E 84-19B test results for hemp concrete showed impressive performance, reaching top marks for “flame spread” and “smoke production” ratings. How Is Hempcrete Used In Construction Regional House Edeghem / BC architects. Image © Thomas Noceto Similar results were verified in this collection of experiments with hemp concrete, where it is observed that hemp concrete forms a barrier between the building structure and the fire. As a non-flammable material, hemp concrete doesn’t allow flames to dissipate. How Is Hempcrete Used In Construction Cortesia de GoHemp When it comes to forces of nature like fire, all necessary precautions are important to preserve lives and resources. That is why so many researchers are focusing on the subject, investigating the behavior of each material in a fire,

  • In short, hemp-based materials provide adequate fire resistance so residents can evacuate in time, reducing the spread of the fire and the risk of inhalation of smoke as it burns locally.
  • In other words, burning a wall of hempcrete will be very difficult and will not have any psychoactive effects.
  • Jokes aside, hemp is still an extremely stigmatized material in many countries but it needs to be addressed seriously.

Its many applications for various industries carry the enormous potential to replace other polluting materials that are harmful to the environment and may become the protagonists of a change in the civil construction industry. About this author How Is Hempcrete Used In Construction Cite: Souza, Eduardo. “What Happens If Hempcrete Catches Fire?” 31 Aug 2021. ArchDaily, (Trans. Franco, José Tomás) Accessed, ISSN 0719-8884

Can hempcrete mold?

Know that hempcrete is NOT structural – Therefore, structural sheathing such as plywood or OSB will need to be replaced with alternative lateral bracing. Hempcrete cannot support any loads from gravity, a roof, snow, wind or a second floor. Wood/timber framing is recommended to carry loads and provide lateral bracing to prevent racking and collapse.

  1. Steel studs and a steel moment frame are also another option.
  2. Hempcrete is actually very similar to wood in many characteristics, except that wood can be structural.
  3. The sustainability of growing hemp quickly and easily is a major benefit.
  4. The hemp plant is apparently resistant to mold, although it is highly absorbent of water.

Mold can grow on the surface of hempcrete, just like other materials, when the conditions are right as the food source can be dirt or dust, but due to the lime component and natural fungal resistance of the hemp, mold will not feed on the hempcrete itself.

Do termites eat hempcrete?

Safety – Most importantly, hempcrete is recognized for its safety features – It is mold, fire, crack, and termite resistant. Mold Resistant: As mentioned previously, vapor permeability reduces the risk of mold, improving the safety of a structure. Once in the home, mold can lead to varying health problems ranging from itching eyes, sneezing, and coughing to severe allergic reactions, asthma attacks, and even permanent lung damage.

  1. Furthermore, once the mold is in the home, it can be challenging and expensive to remove.
  2. The best solution to reducing the risk of exposure is to use a material that prevents mold in the first place.
  3. Fire Resistant: Hempcrete is fire-resistant, an especially important feature for California residents.

Following tests conducted by the American Society for Testing and Materials (ATSM), the researchers determined that the material had a profound ability to resist fire. According to Hempitecture, a construction company that specializes in the utilization of hemp fiber, “the flame spread index and the smoke index developed are two scales used to measure the amount of flame spread and the amount of smoke that is generated.

  • It’s a scale from 0 to 450.
  • Hempcrete got 0, the highest possible rating.” Crack Resistant: Due to the material’s low density, it is more resistant to cracking under movement.
  • In areas at risk of earthquakes, hempcrete can reduce the hazard of potential damage. The U.S.
  • Geological Survey predicts that there is a 72 percent chance in the San Francisco Bay area within the next thirty years and a 60 percent chance in Southern California that an earthquake of a magnitude 6.7 or larger will strike.

If retrofits and renovations were to utilize hempcrete, could we reduce the number of damaged structures? Termite Resistant: Termites destroy approximately 600,000 homes in the U.S. each year, costing Americans over $5 billion annually to control and repair the damage.

Does hempcrete float in water?

Fully cured hempcrete blocks float in a bucket of water. It is not used as a structural element, only as insulating infill between the frame members though it does tend to reduce racking. All loads are carried by internal framing.

What is the lifespan of hempcrete?

FUTURE PROOF – Hempcrete homes are long lasting. The average home is estimated to last 50-100 years. Hempcrete, on the other hand, has the incredible life span of at least 300-500 years, if not longer and is recyclable. It is truly the ultimate building material! To build an even more future proof house, we will also be using bio-technology.

  1. We will put in an off-grid electricity system, solar and wind powered, and use an eco-friendly hot water system.
  2. The septic tank will be providing us with a grey water system, where the filtered water can be re-used for irrigation.
  3. Whenever possible, we would choose an eco-friendly option over non-environmentally friendly option.

In this way we will be able to maintain our zero-carbon footprint once we live there.

Does hempcrete need a vapor barrier?

You need to avoid vapor-impermeable materials in any hempcrete assembly. This is because hempcrete relies on the property of vapor diffusion through an assembly for its thermal performance.

Is hempcrete earthquake proof?

Is Hempcrete earthquake-proof? While hempcrete is not officially recognized as earthquake-proof, it is very durable and up to 3 times more resistant to cracking than concrete. It also helps keep framing studs well supported under load and movement.

How thick does a hempcrete wall need to be?

Hempcrete buildings – thermal performance and costs The thermal properties of hempcrete are extraordinary. It provides insulation because of pockets of air trapped within the material; both in the spaces between particles of hemp shiv, and in microscopic pores in the hemp shiv itself.

  • Compared to synthetic insulation materials, hempcrete is a less-effective insulator, For example 240mm thickness of hempcrete meets current UK building regulations for insulation (compared to around 80 mm of polyurethane insulation board).
  • However because hempcrete is cheaper than synthetic insulation materials, and is used to form a monolithic wall, the usual thickness of hempcrete applied in a new building is 300-400mm for a wall.

The typical thermal conductivity of hempcrete is typically 0.06 to 0.07 W/mK. U-values for hempcrete vary depending on the thickness, the type of binder used, the exact specification, application techniques and the skill of the contractor, however a typical u-value (for a 350mm thick hempcrete wall) is 0.17 W/m2K.

  • Hempcrete also provides thermal mass, as well as insulation, due to density of the lime binder once it has set.
  • This means that hempcrete is able to store heat within the fabric of the material itself (like a giant storage heater).
  • In this respect it is unlike lightweight insulations which only store heat within the air trapped inside the material.

The ability of hempcrete to store heat in this way as well as insulating has two important advantages. Firstly, it allows for natural ventilation of the building. Whereas modern highly insulated buildings rely on airtightness alone to trap the air within the lightweight insulation layer (leading to the use of closed windows – to preserve the heat – with trickle vents and mechanical heat recovery systems to ensure indoor air quality), hempcrete stores heat (from the sun, or from internal heating) in the thermal mass of its walls, to be released slowly as the building cools down.

  1. This means that in a hempcrete home you can open the window if it gets a bit stuffy; safe in the knowledge that all your expensive heat is not going to flow straight out and be lost.
  2. Secondly the slow speed at which a typical hempcrete wall stores and releases heat has the effect of “buffering” natural changes in internal and external temperatures, e.g.

night and day temperature fluctuations, so that with very little heating or cooling a constant internal temperature is maintained. Hempcrete keeps your home cool in the summer and warm in the winter, with a dramatic reduction in fuel bills. Hempcrete is unique in this mixture of insulation and thermal mass.

It can be thought of (in terms of natural materials) as halfway between straw bale (which has loads of insulation, but very little thermal mass) and cob (which has loads of thermal mass and very little insulation). The combination of the two gives hempcrete an extraordinary thermal performance which works dynamically to maintain comfortable indoor temperatures with very little need for mechanical heating, cooling or ventilation.

During in-situ testing, hempcrete consistently out-performs expectations based on laboratory tests and computer modelling.

Does hempcrete require sand?

Hempcrete or hemplime is biocomposite material, a mixture of hemp hurds (shives) and lime, sand, or pozzolans, which is used as a material for construction and insulation.

How long does it take for hempcrete to dry?

Drying Time Rule of Thumb for Cast-in-Place Hempcrete – The rule of thumb in moderate temperature and reasonably dry conditions is one week of drying time per inch of wall thickness. If the wall is exposed on both sides and allowed to dry from each side, the drying occurs from both faces.

Therefore, a 12″ hempcrete cast-in-place wall left exposed on both sides can be dry enough for plaster in 6 weeks, assuming optimal conditions. If the hempcrete is cast against a permanent form, then the cast-in-place drying time doubles to 12 weeks in optimal conditions. This home is an 11″ cast-in-place wall, and our summer thus far has been hot and humid.

However, during the past week, we’ve experienced a great deal of rain and damp conditions.

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Is hempcrete flammable?

The same authors note that testing undertaken by the French manufacturer Isochanvre produced results that indicated that hempcrete is a ‘ non-flammable material ‘, with fire-resistance performance improving over time as the binder continues to carbonate (this time factor depends on the composition of the binder: see

What happens when hempcrete gets wet?

Too much water can increase the length of drying the hempcrete and affect the setting of the lime binder. Studies also indicate that the Physico-chemical incompatibility between the binder and vegetal hemp aggregates can lead to inadequate mechanical hydration.

Is hempcrete toxic?

The Benefits Of Using Hempcrete in Your Construction Projects › › The Benefits Of Using Hempcrete in Your Construction Projects Chris Magwood has been using hempcrete to build since 1998. Hempcrete, or hemp-line as it is referred to in Europe, is a promising sustainable building material.

It is a green alternative to composites such as concrete, mortar and plaster. Today, we take an excerpt from Essential Hempcrete Construction: The Complete Step-by-Step Guide, where Chris outlines some of the benefits of using hempcrete in construction. The building industry does not see very many “new” materials.

The materials used to insulate residential and commercial buildings have remained the same for decades, and most have serious environmental and/or health impacts. As we collectively begin to add more insulation to buildings to lower their energy requirements, the volume of insulating material we use is going to rise dramatically.

  • It makes ecological and financial sense to fill this volume with materials that are annually renewable, low-impact and, ideally, sourced from waste streams or from by-products from other processes.
  • Hempcrete meets all of these important criteria, and compares favorably with conventional insulation materials in many ways.

The ingredients for making hempcrete are not common building materials, and as such they do not benefit from the volume price breaks of other insulation options. Still, even prior to wide market availability and the cost reductions this will bring, the cost of hempcrete is comparable with other insulation options, while bringing advantages over those options in other ways.

  1. The variability in hempcrete pricing is reflected in the chart below, showing that proper attention must be paid to sourcing affordable materials.
  2. Hemp sourced from Canadian producers is considerably less expensive than that imported from Europe.
  3. Hempcrete is unique among the plant-fiber insulation materials (cellulose, wood fiber, straw bale, straw/clay, cotton) in its ability to maintain integrity in humid conditions.

Like all of the plant-fiber insulation options, hemp hurds are able to store a great deal of moisture because of their porous structure; the moisture is adsorbed onto the large internal surface area of the plant fibers and absorbed into the cellular structure.

  1. This storage capacity is very helpful in allowing the material to take on moisture when it exists and to release it when conditions allow.
  2. A study performed in France found that up to 596 kilograms (1314 pounds) of water vapor could be stored in 1 cubic meter (35.3 ft3) of hempcrete, providing storage capacity for a sustained elevated relative humidity of 93% without overwhelming the capacity of the material to adsorb moisture.

The advantage of hempcrete over other plant-fiber materials and conventional insulation types is found in the properties of the lime binder. Lime has a high pH and is inherently antimicrobial and antifungal, and the lime coating around each piece of hemp hurd in the mix creates a surface that resists the development of mold even when the humidity and temperature conditions would cause mold to occur on other insulation materials.

This resilience in the presence of humidity or even liquid moisture makes hempcrete unique among insulation materials and a desirable choice in both cold and hot climates and anywhere where humidity levels are high. Good structural qualities Hempcrete has a density that allows it to play a minor structural role in the building — unlike batt, loose fill and spray insulation materials in the cost chart above.

Hempcrete insulation does not have the structural capacity to fully support roof loads, but cast around conventional wall framing or double-stud framing, it can help restrain the studs from bending or buckling under loads, thereby increasing the load that can be carried by each framing member.

  • Testing at Queen’s University in Canada showed that a 2×6 wood stud with 313 kg/m3 (19.5 lb/ft3) hempcrete infill could support three to four times the compressive loading of a standard stud wall due to the support the hempcrete provides to the wood stud in weak axis bending.
  • The rigidity of hempcrete insulation and the textured surface it presents on the face of the wall makes an excellent substrate for plaster finishes without any need for mesh or other bonding agents.

Hemp is an agricultural crop that has particularly high yields. A study by the US Department of Agriculture found worldwide yields ranged between 2.5 to 8.7 tons of dry straw per acre. This compares favorably to yields for wheat straw of 1.25 to 2.5 tons per acre.

  1. In terms of the amount of biomass available for use from a single crop, no other plant provides as much volume as hemp.
  2. The hemp plant is typically grown for either the strong fiber it produces or for seed (rarely for both at the same time).
  3. In either type of hemp production, the hurd is not the primary use and is considered a by-product.

It has some market value as animal bedding and can be compressed into fuel pellets, but large-scale hemp production can generate tons of hurd for the insulation market as producers supply fiber or seed to their primary markets. According to a 2003 study, 716.6 pounds (325 kg) of CO2 are stored in one tonne of dried hemp.

  1. Tradical, a hempcrete manufacturer in the UK, cites a study showing that their hempcrete product sequesters 110 kg of CO2 for every cubic meter of material (6.88 pounds per cubic foot)6 when the carbon emissions from producing the lime binder are taken into account.
  2. In Canada, about 200,000 new homes are built each year, with an average footprint of 2,000 square feet (185 m2).

If they were all insulated to code minimum requirements with hempcrete, a total of 990,718 tons of carbon could be sequestered annually. If the same homes had walls with fiberglass insulation, 207,345 tons of carbon would be emitted to create that insulation, so the total net carbon savings for the planet is significant.

  • Hempcrete is quite a benign material.
  • The farming process uses far fewer pesticides and herbicides than other grain or fiber crops, creating much less environmental damage due to the use of toxins on the fields.
  • The crop does, however, require liberal use of fertilizer, which can have negative ecosystem impacts.

Harvesting and processing take place without the input of heat or chemicals. The dry, powdered lime binder can generate a lot of dust during mixing, and is highly caustic. Adequate breathing protection must be worn by anybody handling the dry ingredients and working around the mixing station.

When wet, the lime binder is mildly caustic to skin, so rubber gloves and fully covered skin are required. Once placed in the wall and fully cured and dry, hempcrete does not off gas or release any toxins into the indoor environment. The lime is antimicrobial and antifungal, and the material is generally thought to have no ill effects on the indoor environment.

The excellent moisture-handling abilities of the material can reduce the chances of a poor indoor environment due to excessively moist or dry air in the building. Hempcrete is an insulation material, and as such its thermal performance is important. One of the primary difficulties in introducing hempcrete to the building industry is the vagary that currently exists around quantifying the thermal performance values of the material.

A thorough literature review turns up 19 thermal tests on hempcrete conducted at research facilities around the world. The insulation ratings found by these tests vary widely, from R-1.25 per inch to R-2.3 per inch for low- (200 kg/m3) to medium- (400 kg/m3) density wall insulation mixes. Even mixes with the same density vary in the test results.

To meet minimum code requirements of R-24 in much of Canada, these results could make the difference between needing a wall that is over 19 inches deep (488 mm) to one that is a more reasonable 10.5 inches (266 mm). To compound the issue, several in situ tests have shown that the actual thermal performance of hempcrete walls is considerably better than the R-values would indicate.

  • Hempcrete has some properties that are unique among insulation materials.
  • As one very comprehensive test of hygrothermal properties of hempcrete states: “The reasonably low thermal conductivity of hemp lime, combined with phase shift, phase change effects, high internal thermal comfort, low initial energy transfer rates, passive humidity control and lower energy requirement for ventilation, all contribute to the reduction of,” These aspects of hempcrete thermal performance will be explored in the Building Science Notes chapter of this book.

An average of all the test results of mixes in the 275 to 350 kg/m3 range gives a value of R-1.9 per inch (requiring a 12.5-inch wall to reach R-24). The only North American tests performed to date have been at Ryerson University, and are summarized in the table shown here.

We build our hempcrete walls in the range of 12 to 16 inches (300 to 400 mm) wide for northern climate use (climate zone 6), and achieve actual performance results that exceed code expectations. Although the Internet is full of videos of people aiming blowtorches at hempcrete samples, there is not a great deal of certified testing done on the fire resistance of hempcrete walls.

As the homemade videos indicate, the mineral coating of the lime binder around each piece of hemp hurd adds a high degree of flame resistance to the plant material. A 2009 fire test was conducted by BRE Global in the UK to meet the BS EN1365– 1:1999 standard.10 This test subjected a 3×3 meter (10×10 feet) wall of hempcrete that was 300 mm thick (12 inches) to temperatures of 800 to 1,000° Celsius (1800° Fahrenheit), while also subjecting it to a vertical load of 135kN (30,349 lb).

  1. The test showed that the wall met all requirements for integrity, insulation and loadbearing capacity for 73 minutes.
  2. During this test, the mean temperature on the side of the wall unexposed to the flames stayed under 60°C (140°F), and for the first 15 minutes stayed under 30°C (86°F).
  3. This test was performed on a hempcrete wall with no plaster or other finish on the insulation, so real-world performance would be enhanced by protective plaster or other wallboard.

A Canadian fire test was undertaken in 2015 to ASTM E119-14 and CAN/ULC S101-07 standards. The test report concludes that “The test specimen successfully met the conditions of acceptance for a 68-minute Fire Resistance rating,” and included a successful hose stream test.

  • It is worth noting that the lack of chemical content in hempcrete means that the small amount of smoke generated has none of the highly toxic compounds generated when petrochemical wall insulation and components burn.
  • There has not been a great deal of testing of hempcrete’s ability to dampen sound transmission from outside the house or between rooms.

In 2002, a test in the UK was performed on a pair of 6-inch (150 mm) walls with a 3-inch (75 mm) cavity between them, which is a standard arrangement for walls separating units within a building. The hempcrete walls offered sound reduction of 57 to 58 dB, exceeding the 53 dB code requirement.

Low- or zero-carbon footprint Nontoxic materials and high indoor air quality Excellent moisture-handling properties Durability Fire resistance Good thermal performance and very stable indoor temperatures

In exchange for these positive qualities, the builder will face slightly higher initial material costs and additional effort to source the materials from non-standard channels. Current trends in North America are toward carbon reductions, less toxic materials, moisture resilience and durability; a builder who establishes an early foothold in the hempcrete market is likely to be rewarded as more people make choices based on the qualities that hempcrete has to offer.

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One of the key advantages of hempcrete over other natural insulation materials is that it fits well with conventional framing techniques, so although it requires a different installation process than conventional insulation, it does not necessarily require experienced builders to change their approach to framing.

And the formwork used for installing hempcrete is a lightweight version of the formwork familiar to any builder who has worked with poured concrete. Forming hempcrete in a frame-walled building results in perfectly straight and flat walls, so that the aesthetic result also closely matches mainstream expectations.

  1. In particular, hempcrete is a good choice for those who live in extreme climates, either cold or hot, and in places where humidity levels are high for sustained periods of time.
  2. The antimicrobial and antifungal qualities of hempcrete make it very stable and safe when highly loaded with moisture, and can help to prevent mold and deterioration in such conditions.

There is an underlying tension among hempcrete advocates between those with a do-it-yourself philosophy and those aligned with the companies that have proprietary formulations for hempcrete.There are some real advantages to working with materials that have been tested and developed by a company with some history and knowledge and customer support.

At the same time, the materials are simple, straightforward and accessible to those who have a desire to formulate and mix their own hempcrete. There is no right or wrong tactic to take, and it is the aim of this book to cover both options fairly and thoroughly. As the hemp industry begins to take hold in North America, there will be improved supply chains and reductions in cost that will make hempcrete even more attractive.

Early adopters using the material today are helping to set the stage for an increase in the use of hempcrete in the near future. ← → : The Benefits Of Using Hempcrete in Your Construction Projects

Is hempcrete expensive?

Cons of using hempcrete – The largest drawback to using hempcrete to build a house is that it’s still relatively rare and costly to procure, which can increase the building price substantially. “It could increase the cost by up to $100,000 overall, depending on home size,” Keahey Lanier notes.

“Generally, whatever the standard price is for build per square foot, add a minimum of $60 to that. So where it may cost an average of $120 per square foot on a traditional build, a hempcrete structure may cost $180 per square foot or more.” That said, heating and cooling costs may well be lowered thanks to the thermal insulation properties of hempcrete, Knutsen notes.

“So the upfront costs can be a little higher, or the same, but over time you’ll be saving money every time the heater or AC turns on,” he says. And the more hempcrete houses that are built, the larger the demand to create more hempcrete, which the experts say should help reduce both the issues with availability and cost down the line.

  • One final drawback is plain old public perception.
  • Some jurisdictions may make permitting a challenge due to the politically fabricated stigmas surrounding the word ‘hemp,'” Knutsen says.
  • The good news? “The laws are changing for the better, and quickly,” according to Knutsen.
  • In fact, the farm bill signed into law by President Donald Trump in late December specifically removes hemp from the Controlled Substances Act and out of the jurisdiction of the Drug Enforcement Administration.

According to Keahey Lanier, this bill clearly makes hemp a legal agricultural commodity in the U.S.—which could pave the way to hemp being used in all sorts of products, including more houses.

Can hempcrete be used for roads?

Hemp MythBusters — Can hempcrete replace concrete? The Myth Hempcrete can replace standard concrete. The Background Hempcrete is a material that has been around for a long time. The most common mix that we have seen and heard about is made by the combination of hemp hurd (woody inner core), lime and water. It looks like American Hemp, LLC confirms this.

According to, the mix is purported to be a strong insulator, flame resistant, pest resistant, moisture balancing and biodegradable (when exposed to water). Further, it is said to be more sustainable than concrete and a carbon sink. Hempcrete can also be reused through milling and rehydration.

Standard concrete is a mix of sand, aggregate (gravel) and Portland Cement. Concrete works, through a process called hydration where water reacts with the Portland Cement to harden (Popular Mechanics). Concrete is the most common building material in use around the world (Chemistry Society).

Footings (part of the foundation)Stem walls (part of the foundation and sit on the footings)Foundation slabsElevated slabsSidewalkCurbBridgesDamsSeptic tanks

Hemp has been deemed by many as a miracle crop with “25,000” uses and that it “can save the world.” One particular use of hemp, often touted, is the potential to replace, standard concrete. The crop has been reported as better for the environment, easier to grow and “has been suppressed for decades by corporate interests.” “Now is the time for hemp to regain its rightful place,” is a common statement we hear from many people. Concrete Bridge The Data For this myth, we will focus on a few primary data points including:

The cost differentials of hempcrete vs standard concretePerformance limitations of hempcrete

The cost of a yard Concrete is a very inexpensive material, relative to other materials. Here are some data points for concrete:

Concrete is sold by the yardOur examined batch (according to data on our batch ticket) weighs 3,690 pounds per yardA yard is equal to 27 cubic feetOur examined batch (according to data on our batch ticket) weighs 137 pounds per cubic footThe average cost of a yard of concrete is $108 or 10,800 cents (NRMCA)

With that data we can see that the average selling price per concrete is $0.0293 per pound. We’ll model a 40% gross profit margin which equates to a cost of goods sold (COGS) $0.018 per pound. Now this is for the entire concrete mix. Hemp isn’t able to replace everything.

Water — 216 lbCement — 4,065 lbAggregate (¾”) — 10,460 lbAggregate (⅜”) — 2,810 lbAggregate (sand) — 11,970 lbTotal weight — 29,521 lbTotal yards — 8Weight per yard — 3,690 lb

So we can see a lot of weight goes into making concrete. The point here is to break down the concrete mix and see where we can add hemp and what that cost structure would have to look like. We obviously can’t replace the water with hemp nor the cement.

Water — 216 lbCement — 4,065 lbHemp — 25,240 lbTotal weight — 29,251 lbTotal yards — 8Weight per yard — 3,690 lb

Great, we have a mix design. Now to be cost competitive and be able to “replace concrete” we would have to maintain a similar price point of $108 per yard or $0.0293 per pound. That is the selling price, the purchase price to make that would be 40% less (assuming the manufacturer makes a 40% margin).

  • With that the COGS is $0.018 per pound.
  • To keep things simple, let’s assume that the costs are evenly distributed across all the mix components (this is not the real case as the cement is significantly more expensive than the aggregate or water).
  • The value of hemp would be $0.018 per pound.
  • If irrigated land can produce 8 tons of hemp material and 50% of that material is hurd that we will use in our hempcrete, then each acre can produce 8,000 lb of hurd for our hempcrete.

At that production rate and price point, the farmer can expect to gross $140 per acre. The cost of seed alone is going to be $105 (using HGI pricing and seeding at 30 lb per acre). With the cost of seed accounted for, the farmer can expect to gross no more than $35 per acre and that is before the seed is even put into the ground! The real problem is the material must be decorticated, separated and shipped in order to be incorporated into hempcrete.

At the current rates for concrete, it is not economical for farmers to grow hemp for hempcrete. On the supply side, the numbers aren’t looking too good either. What about the demand side, the cost difference of the aggregate or sand compared to hemp? Based on our mix design above, we can see that sand is a major component of the concrete mix.

We found sand pricing at $15 to $40 per yard according to Let’s give hemp the best chance we can and use the higher, $40 per yard, price. The weight of that yard is 2,750 pounds according to DownEaster MFG. With this data the price per sand is $0.015 per pound. Concrete Component Cost Comparison We can see that significant price compression is needed to make hemp a viable replacement for sand. Since sand is classified as aggregate (based on our batch ticket) it is reasonable to assume that other aggregates will share a similar cost differential.

BUT What if this is a waste product? What if the farmer actually grew for CBD or textile fiber or grain or something else? What effect would that have on our hempcrete? Well, in that scenario, we can say that the cost of production is $0 since all the production costs can be applied to the other products.

However, the decortication cost would have to be applied to the hurd unless the target product is fiber, which would be able to cover the decortication expense. We’ll assume that decortication costs are covered by fiber. Now things are starting to look good, right? We have 8,000 lb of hemp hurd per acre ready to be turned into hempcrete.

But here is the problem, that hemp hurd needs to get to the batch plant to be turned into concrete. The last shipping we had to deal with was $1,300 to transport 80,000 pounds of hemp (whole plan) about 144 miles. That is a transport cost per pound of $0.01625 per pound or about 92.7% of the value of the hemp.

We can now see that the cost structure of hempcrete will not allow it to replace concrete unless farmers are willing to net $0.00127 per pound of hemp (assuming all other costs are recorded elsewhere). At that rate, that makes hemp hurd worth $10.16 per acre to the farmer.

  1. With all of that information, making a concrete replacement from hemp would not pencil out.
  2. The economics, whether you look at the supply side (farmer willingness to grow and profit) or the demand side (cost difference of the batch plant switching to hemp) simply doesn’t support this myth.
  3. That being said, there will always be smaller, niche applications of this material.

But the context of the myth is the “Hempcrete can replace concrete”, so we are looking at the potential for that scenario to play out. Thus far, it is not looking good. Hempcrete — Performance We can see the pricing of hempcrete is not competitive but let’s say we want hempcrete for all of the benefits and don’t care much about the cost.

  1. Here we are going to run into more problems.
  2. Again, we are looking at hemp replacing concrete within the construction sector which requires hempcrete to maintain target specifications inherent in concrete.
  3. Concrete is an incredible construction material.
  4. It is inexpensive, non toxic when cured, can last for thousands of years, fire resistant, pest resistant, maintains very good compressive strength and is easy to work with.

It is also water tolerant as we can see in its use of septic tanks, water holding tanks, dams and many more. Hemp in contrast is also non toxic when cured, fire resistant, pest resistant, mold resistant, can last a long time (unless it gets soaked with water which causes it to degrade) but maintains minimum compressive strength.

The primary performance indicator for concrete is compressive strength. During placement, concrete is tested in the field for a few different attributes including, slump, air content, weight and temperature. Concrete cylinders are cast in the field and then cured. The cured samples are tested for compressive strength on Day 7 and Day 28.

To test compressive strength, a hydraulic piston is used to apply consistent pressure until the cylinder cracks or otherwise breaks. Now most concrete must hit a compressive strength of 3,000 psi to 4,000 psi and most concrete (given they are not high in air content) can easily hit this.

  • Hempcrete, on the other hand would not hit this specification.
  • According to, hempcrete has a compressive strength of 0.5 MPa to 3.5 MPa or 72.5 psi to 507.6 psi.
  • At best that is 16.9% the strength of standard concrete.
  • To put that in perspective, according to the Wikipedia page regarding Ground Pressure, a stiletto heel can exert up to 471 psi.
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Imagine seeing someone walk down the sidewalk and their heels penetrating and poking holes in the sidewalk with each step. The reasoning behind this is quite simple. Hempcrete is composed of very little dense material (Hemptopia says the bulk density is 0.152 g/cm3 or 9.5 lb/ft3) whereas concrete contains, sand and multiple sizes of aggregate (with a bulk batch density of 137 lb/ft3 based on our batch ticket).

  • These ingredients each add considerable compressive strength due to their density.
  • No matter where you go, there will be a public work specification which will outline the compressive strength of concrete.
  • This specification must be met or the concrete will be rejected and whatever was made with it removed.

Hempcrete can provide some tensile strength, if the fibers are utilized. This helps reduce surface cracking but does not increase the compressive strength. At this time, we are unaware of any specification for tensile strength. Further, there are many other types of fibers that can be added to concrete to increase the tensile strength including steel and nylon.

So with this we can see that in one, if not, the most critical areas (depending on who you ask, contractor vs inspector), hempcrete just doesn’t provide the same performance as standard concrete and will be unable to without the addition of more dense materials. Also, when exposed to excess water, hempcrete can biodegrade whereas standard concrete can hold up to large amounts of water (think dams that are over 100 years old) for a very long time with minimal degradation.

The Myth — BUSTED As we can see the myth of “Hemcrete can replace standard concrete” simply isn’t feasible. We are not saying hempcrete has no practical use. Many people are interested in incorporating it into their buildings, remodels, etc. In the context of the myth though, hempcrete just doesn’t offer the same critical performance as standard concrete nor is it cost competitive.

  • The cost part is a primary issue both from the concrete producers side of minimizing production costs and the opportunity cost to farmers.
  • In the case of the farmer, all of the costs would need to be shifted before it makes any sense and once transport is factored in, the revenue from hemp for hempcrete is not worth the amount of effort.

Hempcrete may have increased environmental benefits, sure, but when building structures, the most important aspect is safety and ensuring the structure will actually support itself, something hempcrete cannot guarantee (when looking to replace standard concrete given the current accepted mix design).

Can you build a house out of hempcrete?

Hemp Homes: A New Sustainable Building Trend How Is Hempcrete Used In Construction An efficient, economical substitute for nearly all building materials does exist Anyone building or remodeling this past year has seen lumber, steel, and concrete prices skyrocket. Lumber has tripled and other building materials have increased similarly.

  • How can investors who already have tight margins handle the increased prices? How can we continue to build and not outstrip the capacity of buyers to buy or renters to rent? The answer might be, hemp.
  • First let’s distinguish between hemp and its evil twin marijuana.
  • Technically they are both referred to as cannabis.

But they are different species of plants. You can’t get high from smoking hemp. And hemp has a long history of multiple uses. It was one of the first textiles and one of the first types of paper (30 Gutenberg Bibles were printed on hemp paper). It is used in rope and sails (the origin of the word canvas is cannabis).

  • It can be a good food source, has useful oils (known as CBD oils) that are currently marketed for many health uses, and can be made into meal or milk.
  • It can be used for animal feed and bedding.
  • In more modern times, hemp is a good alternative to corn for biofuels.
  • Hemp pellets can also be burned for fuel.

Hemp plastic is biodegradable but cheaper and stronger than the more common petroleum-based plastics. And hemp plastic reduces reliance on fossil fuels. Also, hemp has incredible potential uses in construction. Hemp can be used for insulation. It provides higher ratings, lighter weight, and is easier to use.

Hempcrete can be used in the form of blocks, panels or 3D printed specialty shapes for walls and floors (but not load-bearing walls). Hemp adobe can be used for load-bearing walls, foundations, and floors, and is as strong or stronger than concrete (3,000 – 6,000 psi depending on the formulation where concrete is at around 3,000 psi).

Hemp can be extruded in much the same way as MDF lumber to make plywood, boards, wood blanks, and other lumber replacement products. When made this way, hemp hardness is similar to oak. To renew lumber takes 40 years. To renew hemp takes 90 days. It grows similarly to bamboo when grown for fiber and in some areas of the country you can get three growing seasons each year.

  1. Hemp is also great for the environment since it sequesters more carbon from the atmosphere than most crops.
  2. Building with hemp could be a carbon-negative activity if the agriculture is done right and the materials are appropriately used.
  3. In short, hemp can be used as a primary material for foundations, floors, roofs, walls, cabinets, insulation, shingles, brick or block work, and sheeting.

Hemp is breathable, mold and mildew resistant, a great insulator, naturally pest (termite) resistant, and fire retardant. So why isn’t hemp material readily available across the country and able to fill the gap as lumber and steel shortages (and high prices) continue to slow construction? For 85 years, hemp was unfairly grouped with marijuana as a drug, and it was illegal in the U.S.

  1. And many other areas of the world to grow it.
  2. This changed in the U.S.
  3. In 2018 when hemp was officially and legally separated from marijuana and made legal across the country.
  4. But it’s hard to grow an industry from scratch and most of the hemp growers focused on the high per acre profit potential of CBD oil rather than industrial fiber.

Today, there is no fully supported hemp supply chain to go from farm to hemp lumber or hempcrete manufacturer. Smaller providers have popped up, however, and the long and arduous process of getting hemp products rated for the various construction purposes is underway.

Within the next few years, you will begin to see hemp homes (there are about 50 in the U.S. right now) and hemp alternatives for lumber, concrete, and steel. When a product is better, cheaper, and faster, as well as far more environmentally friendly, it can’t be held down for long now that it’s legal and the rules for growing it have been developed.

There are groups right now who are focused on building this supply chain infrastructure, enabling the creation at scale of hemp building material, and using the materials to develop affordable green housing across the U.S. One of those groups, Empower Unity, is finalizing plans for their initial communities.

  1. They will be leveraging novel 3D printing and modular housing approaches using hemp-based materials to rapidly and cheaply create beautiful well-constructed options.
  2. Be on the lookout for hemp products and learn how you can substitute this green option for lumber, steel, and/or concrete in your own development and renovation work.

This is a trend that is – literally – growing rapidly. Steve Streetman is a real estate consultant specializing in deal structuring and the use of cryptocurrency. Look for his book, “Cryptocurrency and Real Estate: how to profit as Bitcoin and Blockchain transform real estate investing” available now on Amazon in paperback and ebook formats.

Can I make my own hempcrete?

Four parts hemp hurd, one part lime binder, and one part water is all you need to make hempcrete, a durable building material similar to pressboard or adobe. Just fill up the form with hempcrete, tamp it down, and once it’s set, you’re set! How Is Hempcrete Used In Construction Ben Christensen of Oregon Hemp Works and Joy Beckerman of Hemp Ace International explain : Get 15 great people there from you community, you empower them on how to build their own home, much like the Amish barn raising, and you get your building done in a day depending on how big it is.

  • Mix, cast, and tamp.
  • At the end of your hempcrete home’s life, that structure’s life, you can actually take the hempcrete home apart, crack that hempcrete up, and put it into your next hempcrete mix and/or you can use it as some type of a soil amendment.
  • We’re talking about reusable, recyclable, and durable.

It just doesn’t get any better than that. FYI, hemp hurd looks more smokeable than the crappy weed we had in middle school. • How to Make a Hempcrete Wall ( SmuggleVision via Core 77 )

Does hempcrete need to be rendered?

Finishes and aesthetics – The default finish for hempcrete is render, and this is a must externally, to provide a rain skin. The render must also be breathable, so as not to inhibit the inner workings of the hemp. Normal cement render must not be used – it is too brittle, non-breathable, and will peel off very quickly.

Suitable lime-based renders, which are fully waterproof yet breathable, are available from suppliers such as Australian Hemp Masonry Company, Ozhemp and Rockcote. The texture can be varied to suit taste, as can colour. However, many people fall in love with the rich organic colour and texture of the hemp masonry as it comes ‘off form’.

It has a subtle naturally variegated pattern that follows the layers of placement, which can be enhanced with the addition of mineral oxides in the mix. Other objects can also be placed in the wall against the formwork, to be revealed when it is stripped, with spectacular results.

The minor reduction in R values can be forgiven when looking at such things! Off-form is generally sealed to prevent surface crumbling or minor damage using a breathable product like Waterglass. It is worth noting that one of the most spectacular renders is commonly called Moroccan or Venetian (as made by Rockcote).

It’s smooth like glass with beautiful variegated subtle colour swathes and speckles and is entirely suitable for finishing hemp walls in wet areas. It requires an artisan renderer, and is thus a bit more expensive per square metre, but in limited areas may still fit the budget. How Is Hempcrete Used In Construction Many people like to leave the natural, textured finish of hemp.

Is it cheaper to build with hempcrete?

Cons of using hempcrete – The largest drawback to using hempcrete to build a house is that it’s still relatively rare and costly to procure, which can increase the building price substantially. “It could increase the cost by up to $100,000 overall, depending on home size,” Keahey Lanier notes.

Generally, whatever the standard price is for build per square foot, add a minimum of $60 to that. So where it may cost an average of $120 per square foot on a traditional build, a hempcrete structure may cost $180 per square foot or more.” That said, heating and cooling costs may well be lowered thanks to the thermal insulation properties of hempcrete, Knutsen notes.

“So the upfront costs can be a little higher, or the same, but over time you’ll be saving money every time the heater or AC turns on,” he says. And the more hempcrete houses that are built, the larger the demand to create more hempcrete, which the experts say should help reduce both the issues with availability and cost down the line.

  1. One final drawback is plain old public perception.
  2. Some jurisdictions may make permitting a challenge due to the politically fabricated stigmas surrounding the word ‘hemp,'” Knutsen says.
  3. The good news? “The laws are changing for the better, and quickly,” according to Knutsen.
  4. In fact, the farm bill signed into law by President Donald Trump in late December specifically removes hemp from the Controlled Substances Act and out of the jurisdiction of the Drug Enforcement Administration.

According to Keahey Lanier, this bill clearly makes hemp a legal agricultural commodity in the U.S.—which could pave the way to hemp being used in all sorts of products, including more houses.