Hempcrete Stool
Design and photography by Ian Anderson
Published in Fall 2019
In making this stool, you will be producing an unconventional yet efficient building material with both insulation and thermal mass properties. Made up of hemp hurd, lime, and a binder material, hempcrete (as a single material) is a natural and carbon negative alternative to the abundant layers of insulation, drywall, cladding, etc… that cover the walls of our homes today. In some ways, the simple instructions for this stool are the same as instructions for building a wall of your home with this material. More on hempcrete here. The simple assembly process takes up to 1 hour to complete.
Assembly
Index
Parts
Hydrated Lime
Quantity required: 20lb (9kg)
Portland Cement
Quantity required: 5lb (2.3kg)
All Purpose Flour
Quantity required: A small hand full
Tools
Cardboard
Packaging Tape
Mixing Bucket
Protective Plastic or Rubber Gloves
Disposable Cup
Alternative Parts
Metakaolin
*This material is much harder to obtain, but it is a by-product of some glass production, so less ecologically destructive to use than portland cement.
Replaces: Portland Cement
Quantity required: 10lb (4.5kg)
Help Each Other
Hi there,
I’m trying to build a table and need a sturdy, heavy pillar base that I’d love to DIY instead of buy. Any ideas for firmly joining this stool to a slab of wood to make it serve this function?
Hi Andrew,
This could definitely be done! You would need to insert a sturdy piece of wood in the core of the stool (basically in place of the cylinder in step 9. Then you can attach a flat piece of wood to the top of that wood core, then attach the table to the flat piece of wood (this extra flat piece of wood in the middle is so that you can attach the table top with screws from the underside. If it is a large table top, be sure that this hempcrete cylinder diameter is an inch or two wider than these dimensions. Also, this will be very heavy, and not indestructible, so keep that in mind for when you are moving it around.
Is it possible to create something without the concrete, just hemp and lime?
You could, but it would be a bit more brittle for a longer period of time. The concrete helps to stabilize the mixture while the lime hardens over a period of a year or so. An alternative for concrete is listed in the parts section, which will help stabilize the lime more quickly. Good Luck!
Hello good morning! I am doing a final project for the university, it is related to vertical gardens, for my structure I need a moldable material like this, only that it will be in contact with a humid material all day and every day of the year, could it be ruined? Is there any way to make it waterproof? at least on the inner surface
I don’t think this will be the best material for your project as it will get waterlogged and deteriorate with soil up against it. I would recommend a brick of some sort and mortar.