The idea of using naturals materials as building materials is not new, for example adobe, cob, cordwood, rammed earth, and straw bales. Therefore instead of using blowing agents as insulating materials like foam, use growing agents, such as “mushroom materials”, in other words made of agricultural waste and fungi. The advantages are that it uses natural materials, doesn’t have the global warming issues associated with the blowing agents in foam insulation, and has much lower embodied energy (energy to produce the material).
The science behind this material is the use of something called “Mycelium”, which according to Wikipedia is the vegetative part of a fungus, consisting of a mass of branching, thread-like hyphae. Fungal colonies composed of mycelium are found in soil and on or within many other substrates. (Picture 1)
Picture 1. (Mycelium)
The company Ecovative Design plans at first to grow insulation that can be used in board form and as structural insulated panels (SIPs) (Picture 2 and 3). As part of their project they developed a model house called “Mushroom Tiny House”, which is basically a grown-in-place SIP. (Picture 4)
Picture 2 & 3. SIP with grow insulation
Picture 4. “Mushroom tiny house”
Here is a link of the company Ecovative Design about the principles of building the Mushroom tiny house.
R-Value and Indoor Air Quality
According to Ecovative Design designers, they are benchmarking their product against extruded polystyrene (XPS). But R-value of XPS is about 5 per inch, and mushroom insulation ranges from 1.8 to 4 per inch. That means that your walls are going to have to be thicker with mushroom insulation.
On the other hand, the substrates used as the filler material that the mycelium feeds on and weaves together are sterilized to prevent other organisms from growing. There won’t be any problems of having fungus and spores because they are only using mycelium. So no mushroom will grow from the walls. Then, once the mushroom insulation has finished growing, they hit it with steam to stop the growth.
In my opinion, it should be considered the smell of the use of the materials involved, especially during the growth, and after it has finished growing.
None of the mushroom insulation products is ready for market yet. Their longer-term plans include using it to replace as many environmentally harmful materials as possible: plastic foam, acoustical tiles, medium density fiberboard (MDF), particle board, adhesive, and engineered wood. One advantage of their materials is that the mycelium is their adhesive, so they don’t have to use the stuff with volatile organic compounds.
Finally, I hope to see this kind of material initiative on the market soon. There’s an article from the New Yorker Magazine called “Form and Fungus” that talks about the possibilities of mushroom for replacing foams, BUT you need to subscribe to get access to the full article.
Green Building Advisor. Article “ Grow your own green…Insulation. That is”
Mushroom Tiny House
The New Yorker