Construction Materials and Techniques
Underground Construction Techniques
W. W. Staley. 1962. Timbering and Support of Underground Workings for Small Mines. Bulletin No. 21, Idaho Bureau of Mines and Geology. ID, US. Available from idahogeology.org/pub/Bulletins/B-21.pdf.
Mike Oehler. 1983. The Low Cost Underground House Workshop. Video Series. Mole Publishing Co., ID, US. Available from permies.com.
Mike Oehler. 1997. The Fifty Dollar and Up Underground House Book. Mole Publishing Co., ID, US. ISBN 0-442-27311-8. Available from undergroundhousing.com (paper) or permies.com (digital).
Mike Oehler. 2007. The Earth-Sheltered Solar Greenhouse Book. Mole Publishing Co., ID, US. ISBN 9780960446407. Available from undergroundhousing.com (paper) or permies.com (digital).
Extensions upon Oehler's Method
- Evaluate the extent to which a compost tea 'reticulation' system can be used to accelerate the growth of both fungus and grass roots on the earthen roof to accelerate its stabilisation
- Use Mechanically-stabilised Earth on the immediate outsides of the wall shoring
- Use cold wells as emergency water drains to provide 'surge capacity' during heavy rains (on top of their passive warming during winter)
- Bury, say, IBC tanks under the decking of the bottom-most 'uphill patio' level for capture more water
- Inside, use mechanically-raisable cylindrical 'racking' to provide more accessible cold-storage for food (e.g. a bit like this excerpt from Dirksen (2019))
Reinforced Earth
Mechanically Stabilised Earth
Practical Engineering. 2016. Sand Castle Holds Up A Car! Mechanically Stabilized Earth. Video. Retrieved from youtube.com/watch?v=0olpSN6_TCc.
This video provides a quick introduction to the concept of reinforced, or 'Mechanically Stabilised Earth', along with a couple of simple practical demonstrations of its load-bearing capacity.
Using fabric from an old t-shirt, an 8“ cube of sand is able to support the weight of the presenter; using 9 or 10 squares of fibreglass window screens, an 8” cube was able to support an approx. 250kg load with only negligible deformation. Under dynamic stress, the window screen-stabilised cube survived the impact of an 9kg dumbbell dropped from approx. 2m without too much damage.
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Myceliated Earth
In the context of earth-integrated construction with non-trivial thickness of living roofs, and given how deep the roots of common grasses can grow given the right kind of soil, can a compost-tea 'reticulation system' be used to apply — and accelerate — (a) the 'colonisation' of the roof layer with fungal hyphae that provides a kind of 'fibre reinforcement'; and (b) the development, on the macro-scale, of a rich web of roots to further stabilise the roof and protect it against heavier rains and the erosion which might otherwise occur?
Mycelium-based Materials
Construction Panels
Paul Wheaton. 2021. Podcast 518 - Insulation made from Mushrooms, from the permies.com Permaculture Podcast. Available from https://permies.com/wiki/150646/Podcast-Insulation-Mushrooms.
From the episode's description:
Wood and straw bales have an r-value of 1-2/inch – not that much, but quite a bit when a bale is 18” thick. Mycelium boards r-value depends on its density and how completely it consumes its substrate, but is usually comparable to rockwool which has an r-value of between seven and twelve, and up to 17 per inch. Rockwool has an r-value of 5/inch.
In order to keep the mycelium from trying to turn your house into a compost pile, it has to be baked. This presents a problem because you have to bake the inside of a thermal insulator. More problems come from trying to cut the stuff, with the best fungus for insulation so far also being very difficult to cut from a combination of simple toughness, its fibrous nature, and its tendency to gum up sawblades. Water jet cutting is out of the question, seeing as adding water to the insulation might make more mushrooms rather happy.
The substrate will need to be inoculated with spores, then kept warm and moist for about 10 weeks before being ready to cook. When done, it’s non-flammable, mice don’t like it, repels insects, and resists mould. Plus, the substrate produces mushrooms while it’s growing, which is just added value, although getting more than one crop will mean having to delay getting the insulation.
When ready to cook, the mycelium can be removed from their trays as they’re rigid, and cooking the insulation requires the temperature to reach 200F for about four hours to stop it from growing. Killing the spores requires the temperature to be higher, but they need water to grow, so unless there’s water seeping into your house, there’s not much chance of mushrooms sprouting from your walls, and if there is, there’s bigger problems.
See also the Mushroom Insulation thread in the 'Natural Building' forum at permies.com.
Also to review:
Mycelium Foam
See, for example, Is Mycelium Fungus the Plastic of the Future?