The Pros And Cons Of Using Hempcrete
Since the US Government legalized the cultivation of hemp for industrial purposes last year, companies have been scrambling to plant it, and builders have been scrambling to get their hands on it to use as a building material.
Hemp? A building material? That’s right. Hemp has been used to construct buildings, bridges, walls and more for thousands of years. In fact, there are extant hemp and mortar buildings and bridges sprinkled throughout Europe today. Some of which are more than 1,500 years old.
So why haven’t we heard of this before? Mostly because around 90 years ago, the US government prohibited hemp and eventually listed it as a controlled substance in 1970 when cultivation became a crime.
Once that occurred, builders moved on to materials that wouldn’t get them arrested. But now hemp is back in a big way. And Hempcrete (the mixture of hemp and a lime binder) is one of the hottest materials in the building trades and it’s going to grow massively in the USA in the next 10 years.
So Is Hempcrete a viable solution to Concrete?
It has a lot of potential and numerous advantages over concrete (some massive environmental ones), but in terms of the infrastructure/production, it’s going take some time to be able to compete.
The main problem is that it’s slow to cure, so for load bearing walls and foundations it’s not often used still.
that being said, there are a ton of companies starting to produce hempcrete blocks that are cured prior to sale though. It’s just a question of how the supply of them scales. With the amount of hemp grown currently in the US and the way it is increasing, it will be interesting to see.
Concrete is so readily available at the moment, like everywhere, and it’s hard to overcome that.
What Are the Advantages of Using Hempcrete?
The advantages of using hemp as a construction material are many. Let’s take a look at 15 of those advantages now.
1. Environmentally Friendly
Hemp is considered one of the most environmentally friendly building materials there is for a couple of reasons. First, no herbicides or pesticides are needed to grow it.
This means no harmful run-off. That’s important in farming communities that have often had to deal with groundwater contamination from pesticides. Second, you can bring a crop from seed to harvesting in just 5 or 6 months.
This means that annual yields can be doubled over other crops, and less land has to be dedicated to cultivation.
2. Low Carbon Footprint
During its growth cycle, hemp absorbs unusually large amounts of carbon from the air. This is crucial because of carbon’s role in exacerbating the greenhouse effect.
But for plant life to absorb CO2 is not unusual. What makes hemp stand out, is that it continues to absorb carbon even after being harvested and employed as a building material.
In fact, it’s one of the few building materials aside from thatch that has this ability. As a result, its future seems bright.
3. Excellent Insulation
Whether poured into molds or used in block form, hempcrete absorbs heat during the day and stores it in the thermal mass of the wall. Once the sun goes down, this heat is slowly released into the building.
The insulation characteristics of hempcrete stem from its ability to trap heat inside hollows within its structure. It’s not quite as effective as some synthetic insulations.
But it’s less expensive and will be more than adequate for most structures in non-extreme environments.
4. Absorbs Tons Of Carbon As It Grows – And It Grows Quick
Builders are like everyone else these days; working hard to find more sustainable ways of conducting business. Among other things that means examining where and how materials are sourced.
Among the many things that make hemp attractive to builders is that it absorbs a ton of carbon during its growth cycle.
And that cycle is short enough that the field can produce two crops per year. Thereby cutting down on the amount of land that’s required for large scale cultivation.
5. Non-Hazardous and Non-Toxic to Work With
Fiberglass makes a generally excellent insulation material for some of the same reasons as hemp or hempcrete. But, according to the National Toxicology Program it (fiberglass) is “reasonably anticipated to be a human carcinogen”. That means that while the evidence is not conclusive, there is sufficient reason to believe that regular exposure may cause cancer. There are no such worries with hemp or hempcrete.
6. Thermal Mass
Hempcrete, sometimes called “hemp lime” does a much better job than standard concrete, brick or other masonry construction at storing heat.
The thermal mass properties of hempcrete mean there is less need for aggressive heating or cooling strategies and appliances. And that it is likely to significantly reduce costs related to temperature maintenance.
And of course, less energy consumed to keep your home or business warm or cool, means fewer greenhouse gases.
7. Fully Recyclable
Because hempcrete is bio-based, it is recyclable. When a hempcrete wall or structure reaches the end of its useful life, it can be broken apart and used as a mulch.
Just sprinkle around the base of bushes or trees. In time, it will break down with the hemp and lime components becoming beneficial fertilizers.
Compare that to other construction materials like steel, aluminum or even straight concrete; which needs to be crushed and usually winds up in a landfill.
8. Natural Pest Resistance
Hempcrete is celebrated for being fireproof. It also does a good job repelling mold and mildew. But where it really has it all over wood, is in the fact that it is naturally termite resistant.
Because of its ability to repel rapacious termites, there is no need to treat hempcrete with formaldehyde or any other potentially dangerous chemicals that are commonly used to bolster pest resistance.
9. Absorbs Water
Hempcrete has the ability to absorb moisture and regulate humidity levels in the home or business. This is one of the most outstanding characteristics of hempcrete.
Air pockets created in the material actually pull moisture from the air when humidity is high, and then release it back into the environment when humidity is low.
This is another reason hempcrete structures save on HVAC costs. The low and stable humidity also fosters greater health in the building’s occupants.
10. Insect, Rat and Pest Resistant
While hempcrete can sometimes take on the appearance of fiberboard, it is far more robust than that lumber byproduct.
Like straight up concrete it cannot be compromised by rats, mice, insects or other types of pests.
And because it tends to maintain constant low moisture levels, it also resists the formation of mold and mildew and won’t play host to potentially dangerous bacteria.
11. Natural Disaster Resistant
Often the only buildings left largely intact in the aftermath of hurricanes are concrete ones.
While hempcrete does not provide the load-bearing capabilities of concrete, it nonetheless exhibits an impressive ability to bolster wood framing.
Strengthening that framing by three or four times. In earthquake prone areas, hempcrete is a better choice than concrete because it exhibits superior flexibility. Meaning your home or business will twist and bend without breaking.
Whereas a concrete structure would likely crack and perhaps collapse.
12. Strong and Durable with a Long Life Span
As we mentioned at the outset, there are hemp and mortar structures in Europe that date back to medieval times.
While your hemp house may not wind up lasting 1,500 years or more, it’s nice to know the potential is there for it to last every bit as long as or longer than your neighbors’ homes built using more conventional methods.
13. Can be Used to Create an Air-Tight Seal Around Your Home
There are a lot of potential benefits of having your home sealed against the elements.
Your HVAC system will run far more efficiently, air quality within the home will improve, you’ll enjoy fewer drafts, lower energy bills and won’t fall victim to potentially dangerous molds.
Hempcrete can be used to create an air-tight seal for your home. It forms a denser and more formidable seal than concrete or mortar.
14. Now Also Available as a Plaster or Block
As the hemp industry in America gets to its feet, hempcrete products are becoming available in a wider variety of forms.
Whereas until now, hempcrete blocks needed to be imported from places like the UK, building material companies in the US are now ramping up hempcrete block production.
The result being that prices are dropping across the board. In addition, hemp based plaster has recently appeared on the domestic market.
15. Perfect for Use in Extensions or Renovations
Hempcrete is fast becoming a favorite material for use in home renovations and additions.
Its versatility, affordability, fire-resistance, moisture stabilizing properties, and ability to keep pests at bay make it appealing to homeowners.
While it typically isn’t used alone in the construction of load-bearing walls, it can nonetheless, as we have seen, magnify the strength of wood framed walls. Thereby enhancing the potential longevity of the addition, and adding an extra level of structural integrity to the renovated portion of the house.
5 Disadvantages of Hempcrete
1. Lack of Knowledge With Builders
This is one of the major issues facing those who desire to use hempcrete in their new or renovated home. Hemp production was only legalized a little over a year ago after 9 decades in the legal wilderness.
As such, much of the old knowledge about building with hemp has been lost and needs to be relearned by construction companies.
So finding one that can accommodate your desire for a hempcrete house will likely be a challenge. At least in the near term.
2. Can Add To The Up Front Costs
Since the materials, particularly the hemp itself, are still not exactly common, you may have to look far afield to secure all you need. And this may increase the upfront cost of construction.
Over time, however, any excess costs should be more than covered by energy savings. In addition, you may wind up being eligible for savings on your homeowner’s insurance since hemcrete is fireproof, secure and will stand up to most natural disasters.
Not convinced hemp is fireproof? This video should put any doubts to rest.
3. Not As Readily Available As Concrete
Hempcrete is likely to add some upfront cost to the construction of your home, business or addition.
But that’s largely because you may have to look quite far to find a hemp supplier. Concrete on the other hand is available in every city and virtually every town in the US.
Not only that, but every construction company knows how to work with it. At the moment hempcrete simply can’t compete with that kind of convenience.
4. Not Usually Used as a Load Bearing Material
Leaving aside the fact that hemp is not yet widely available, hemp construction has one significant practical drawback.
Because it is slow to cure, it can’t really be used to pour into a mold to create load bearing walls.
However, as we mentioned above, more and more companies are beginning to produce hempcrete blocks. They are cured prior to sale, and can be used in place of cinderblocks.
5. Not Usually Used in Footings as it May Rot if Permanently Wet
Just as it is inadvisable to use hempcrete for load bearing walls, it is also inadvisable to use it for foundations and footings. First because, as we mentioned, it takes quite a while to cure.
And second because of its ability to absorb moisture. When used above ground, this is not an issue. In fact, it’s a benefit because it helps regulate humidity levels in the house.
Below ground, however, there will be no way for the hempcrete to release the moisture it absorbs. And so, over time, it will begin to break down.
After nearly 90 years in the legal wilderness hemp has finally been allowed to rejoin the family of building materials. It’s one of the most exciting and promising developments in construction in decades, and seems likely to change the face of home construction as we know it.
Whether you are building a new home from the ground up, renovating an existing home or building an addition, you owe it to yourself to investigate the possibilities of hempcrete construction.
Hemp has been a viable building material since before the days of the Roman Empire. And now that it’s finally come in out of the legal cold, it’s poised to change the way homes are constructed for the better.
Lightweight, incredibly durable, flexible, fireproof, pest proof and possessing outstanding insulative capabilities, hempcrete will help you create the home of your dreams, and insure that it will stand the test of time.
But don’t just take our word for it. Check out this video to see what others are saying about this amazing material, and to learn a bit about how hempcrete is used to create some of today’s most beautiful and most sustainable homes.