When hemp has been made into a hemp-lime composite it is extremely fire resistant. If fact, hempcrete scored a perfect 0 in analysis carried out by ASTM, the international standards organization. It didn’t catch fire under any ASTM fire tests.
Hemp, prior to processing is a raw agricultural commodity. It should be stored like hay and other farm commodities. “Organic material with low moisture content in a large unmonitored pile with limited air exchange is a prescription for spontaneous combustion,” according to Agri-Facts, Alberta, Canada.
Two Recent Fires are Cautionary Tales
Hemp mulch bundles stored tightly wrapped and stacked caused a fire in Sauget, IL. The stacks of hemp mulch met all the conditions for spontaneous combustion. The heat from the natural decomposition of the material was unable to be released due to tight storage.
This is a common problem with hay, large municipal compost piles, and livestock bedding materials if left unmonitored.
An outdoor fire at IND Hemp was spotted by the owner Morgan Tweet and Director of Operations Patrick Rose. With the help of the local fire department the fire was quickly brought under control.
IND Hemp has had a warm steady rain, just enough to create hot spots in the hemp mulch piles. This is the same kind of spontaneous combustion that occurs in compost piles.
How Should Hemp be Stored to Avoid These Issues
Hemp is an agricultural commodity and should be treated the same as hay or straw until processed. If it has to be stored the bales should be monitored for hot spots, especially in the summer.
The recipe for spontaneous combustion is:
- Relatively dry material
- Dry pockets
- Large well insulated piles
- Limited air flow
All of these ingredients are present in stored hemp. Time and lack of monitoring are the critical ingredients that can spell trouble.
Morgan Tweet of IND Hemp stated, “Let this be a lesson for those in the industry that may be stock piling old, out of spec, or compostable product.” Under the right conditions hemp is combustible just like hay.