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Hempcrete

Plumb-bob

Registered User
Joined
Aug 31, 2022
Messages
214
Location
BC
I have been approached by a local native band that is exploring the possibility of using hempcrete for local construction projects. They are conducting a feasibility study now.

Building Codes on indian reserve lands in Canada gets very complicated, but basically they are not subject to building codes as is the rest of the country.

I see the ICC is doing some work with hempcrete. Has anybody here had a hand in this?

I would be interested in getting information from anybody that has dealt with hempcrete from a building code perspective, or really any information at all.

Thanks!
 
Nicely done website, lots of good information. Appears to be a french product. They claim no insulation is needed, but i didn’t see an R value. Looks like it’s designed to give an adobe-type house.
 
Basically like an updated version of adobe or cob, but somewhat lighter weight so it has more insulating value. Hempcrete is considered insulating infill, but it has structural support due to its bending and compressive strength - which isn't great but it feels hard and continues to strengthen over time. The best way to describe its application is Bones + Body + Skin, where wood framing is the bones of the structure, hempcrete becomes the whole body around the framing and it gets finished with a skin of plaster, stucco or some other protective finishing product (generally, although some people choose to leave it unrendered.) R-value is 2 to 2.5/in. and walls are generally 12" thick, so roughly a R24 - R30 wall, with better performance recorded than the R-value due to its thermal mass and humidity regulating benefits. Originally "rediscovered" in France in the late 80's but being used all over the world now.
As for building codes, there is nothing in the Canadian code specifically, and the IRC is looking to include in as an addendum, but there are many projects built in North America with this material, so it is possible (just not in urban areas yet.) Would be happy to speak with anyone that is looking for more information @Plumb-bob if you want to send me a message.
 
There's s lot more than the one I posted link to. Hemp as building material big draw seems to be environmental. The few times Ive poked my nose into it the price is not really competitive with other building materials and systems. There are lots of things to like though.
 
Yes there is lots of different information on the internet, as well as many different videos. We started this site, which has some helpful info and videos to start: www.hempcretewalls.com.
Pricing for hempcrete is generally higher due to the fact that the industry is in its infancy, and it doesn't get the subsidies and support that conventional building materials and supply chains do. As the industry grows, it will become competitively priced, especially when comparing products that have the same highly comprehensive performance as hempcrete. It's best when these things are viewed through an WBLCCA (Whole Building Life Cycle Cost Analysis) as opposed just looking at the initial building cost. Of course, when carbon taxes are put at the level needed for sustainability, then hempcrete will seem cheap, especially considering how long it lasts for.
 
(stepping up on my soapbox)

I had a friend way-back-when (a licensed CPA working for a large national firm) who told me he was having a house built. I asked why he didn't ask me to design it for him, to which he replied that the builder was giving him the plans "for free". I told him - point blank - that he was NOT getting the plans "for free" - they were simply building the cost into the total cost of the house, and he would be paying for the plans *for the life of the loan* - which was WAY more than what I would charge for the drawings. He kept insisting that no, I was wrong .. he was getting the plans for free!! No matter how you try to spin it, when you have to sell the cost (be it hempcrete, solar, or "we'll design your house for free") as a "life cycle cost" the only one making money is the original contractor.

Personally, I see this the same way that I see the "Net Zero Carbon" issue - "NZC" building is about showing a mathematical formula that claims you are not contributing to global warming (either through paying for "carbon credits" or smoke-and-mirrors that you are utilizing "carbon-neutral" materials). When I was in college, in one of my algebra courses I couldn't make one of our assignments match the formulas match the "textbook" example, but I could show (by hand!) that I could get the right answer. I spent a half-hour with my professor going over my formula, and in the end he stated "I don't know how you did it - because it shouldn't - but your formula works!" That was when I learned that you can make ANYTHING pencil if you throw the right "formula" at it.

(stepping off of my soapbox .. for now. Sorry for the negativity, but I've finally reached that age, too.)
 
I have been approached by a local native band that is exploring the possibility of using hempcrete for local construction projects. They are conducting a feasibility study now.

Building Codes on indian reserve lands in Canada gets very complicated, but basically they are not subject to building codes as is the rest of the country.

I see the ICC is doing some work with hempcrete. Has anybody here had a hand in this?

I would be interested in getting information from anybody that has dealt with hempcrete from a building code perspective, or really any information at all.

Thanks!

FYI: There's a company out of Alberta (https://justbiofiber.com/) that's been delving into a hempcrete block product, and the company has undertaken engineering studies as well as CSA certification for things like vapour permeance.

If the housing is federally funded, it's possible the feds have attached conditions such as Code and CSA standards.....

PS : For those (especially Americans) wondering why First Nations would be exempt from Code, in Canada, the provinces establish the building code, but First Nation communities are considered wards of the federal government, and since there's no over-arching federal decree on Codes ... plus Canadian First Nations also have (depending on the area/location) some degree of independent sovereignty, esp from provincial regulations.) It's quite messy.
 
then hempcrete will seem cheap, especially considering how long it lasts for.
Didn’t your 5th grade teacher tell you not to end a sentence with a preposition? (Sorry, couldn’t resist)

On point … the whole life theory has some merit, but not a lot. The roof, windows, doors, plumbing, hvac share the same lifespan as a traditional house, so the only variable is the walls. Thinking about that, not many houses have exterior wall failure by itself. Usually it’s a domino effect from a leaking roof, or improperly flashed windows.
 
Thanks all for the feedback.

The person putting this proposal together is not a construction industry professional, so from the outside something like this seems to make sense. One of the big selling points they list in the proposal is the hemp can be grown locally, so it would reduce or eliminate supply chain issues. And local nation members can grow the hemp and construct the buildings, growing the industry to the point where it can be sold to other communities.

However, if hempcrete is used for wall construction, it will only replace several materials: Lumber, plywood, insulation, poly, gwb, etc. We have plenty of lumber and plywood locally, so the list of materials that it would replace is very small. All of the other materials and systems like electrical, plumbing, mechanical, roofing etc etc will still be required. Add in that they will now need a timber frame (very specialized tools and knowledge) to support the vertical loads and the proposal starts to look pretty far fetched.

Cool product and system, but not for the application it is proposed.
 
Add in that they will now need a timber frame (very specialized tools and knowledge) to support the vertical loads and the proposal starts to look pretty far fetched.
The hemp blocks aren’t strong enough for that?
 
Some of this depends on the expected level of performance too. The hemp might be strong enough to prevent the house from falling down but may have expansion and contraction issues where you would still want timber frame around it to minimize interior joint cracking.
 
FYI: There's a company out of Alberta (https://justbiofiber.com/) that's been delving into a hempcrete block product, and the company has undertaken engineering studies as well as CSA certification for things like vapour permeance.

If the housing is federally funded, it's possible the feds have attached conditions such as Code and CSA standards.....

PS : For those (especially Americans) wondering why First Nations would be exempt from Code, in Canada, the provinces establish the building code, but First Nation communities are considered wards of the federal government, and since there's no over-arching federal decree on Codes ... plus Canadian First Nations also have (depending on the area/location) some degree of independent sovereignty, esp from provincial regulations.) It's quite messy.
It is similar in the US. Same issues with military bases. They even have this issue with federal buildings.
 
Proposal RB 316-22 for the 2024 IRC was for a hemp-lime construction appendix. It was approved as modified by the committee and there were no public comments. I do believe this will be in the 2024 IRC. I am not knowledgeable of the technical details.

You can read the new appendix proposal at this link. It's second to last. RB-316: https://www.iccsafe.org/wp-content/uploads/IRC-Building_compressed-GROUP-B-2022.pdf
 
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