I am interested in these wofati hobit homes, but For me I have a few put offs!
the decay and rotting! Being the biggest!
So the stones, used, could they be swiched out to ingenous, with low porousness, or if porous rocks were required could one not soak the stones, in a mixture of diluted Glue. to plug up the pores.
Also grass, Not a fan, I do not like it because grass it the hydration machine its like a net that prevents errorision, slows down water and helps it to soak. not something I particularly want on my home, I would prefer moss! but even then I would like to make a roof before hand out of tiles, with the water flow moving away from the home.
I would also like to add drainage lines made from high angular hard rocks. with the tile roof leading to the drainage line, and moving all the water around the home to be collected elsewhere.
I would also like an ownings over ventilation windows, and multiple vents.
I would also like to a gravity fed water system for bathing using a savoy system. or solar,
and a wind mill, to power a grinding wheel and a lath.
I would like a septic system to lead away from the home into a Biogas tank,
I would also want to coat all the wood in tar!
and a willow arbour walk way, in between zone 1 and 2.
I would also want some sky lights and some solar lights!
I would want to compact that earth around the structures as much as possible and run some hoses to help improve the rate of CBR, as well as take multiple soil samples to determine it the particle size distribution was good enough to compact in the first place!
I would also try and work on more angular joints, methods. with wooden pins, switching to wood is better because metal will expedite issues to wood!
An I would make virtual tours, using scanning software, so people could look at them online, and I would stage the structure because your trying to sell people on the idea!
Rotting wood: if built properly, there should be little to no wood in contact with soil or water. Assuming your site doesn't have a high water table (which can vary throughout the year), posts in holes should do well if sitting on top of several inches of gravel, with gravel filling in the sides as well. You could also layer those post holes with landscape fabric or something else to reduce the chance of soil reaching the wood. The outer walls should have a layer of waterproof material between the wood and the soil as well. The outer walls will be protected by the several feet of roof overhang.
As far as coating wood with tar, I'm not sure if the house would be very livable afterwards, tar seems like pretty nasty stuff to have around your home. There are other options for protecting wood, searching for "natural wood preservatives" will give you various options, based on what the web page considers natural.
You mention grass, do you mean for the living roof? Does moss require more consistent water/moisture? A well-draining roof might be too dry for moss but I'm not sure. I was thinking of sedum personally, since the roof soil is likely to be very dry relative to the rest of the site. Sedum is a common option for green roofs as it can handle less water. But you could plant a variety of plants based on how much soil you put over the roof and how much rain your site gets, and see what survives. You could put a conventional roof on as well like tile or metal, although such a roof would certainly stand out from overhead (if that matters to you). But such a roof could feed into a gutter that sits on top of the earth berm and collect all the rain to store for later use that way.
Since the wofati design has the waterproof umbrella extending out, there's nothing stopping you from having the edge of that umbrella turn up to create a water-tight channel with gravel and/or drain pipe leading water away to a collection point. As far as gravity fed water, you can locate a water storage tank at some point higher than your faucets. I was thinking of a 200-300 gallon tank built into the earthen berm under the insulating umbrella for mine, which would be touch higher than the sink but not high enough for a shower head.
If you follow Mike Oehler's design principles for light, you should have plenty of light without the complexity/issues of skylights. Keeping the roof water-tight is really important, even more when you're working with a thick, heavy, green roof. But some of Mike's designs are essentially skylights, check out this which has at least one in his ridge house:
The wofati design is based off of Mike's design principles so there's plenty of overlap.
The power systems and gray/black water treatment you use can certainly include a septic system if that's what you prefer.
I'm not quite a lumberjack, but that's OK, I sleep all night and I dream all day; I'll coppice trees, I'll grow my food, and compost poo and pee! With a well and off-grid solar, it's a permies life for me! https://www.youtube.com/watch?v=FshU58nI0Ts
I feel that this thread is not going to be productive, I do really appreciate you significant amount of time and energy you put into your Post!
I have 23 years of renovating, 100 yr old homes with my dad, so I have significant experience dealing with these issues!
I also have experience as an engineer, and have studied, Soil mechanics, Hydrology, Structural engineering, Geology, Road design etc.
I feel that this thread will require me to spend significant portions of time explaining the science and explaining how to calculate these things.
The other issue is that each person discussing this may make various assumptions without mentioning these assumptions, this will cause miss communication, as this forum is Global. This discussion will likely be More time consuming than, beneficial.
I end this discussion, and finish with a history of a word,
Advise come from the Latin, Ad meaning Before,
And videre meaning to see.
I thinkMike Oehler's designs and creations were brilliant. He solved a problem using the materials available to him and a lot of physical labour. Paul expressed his admiration for Mike by applying his own creativity to the original design and coming up with what appears to be a significantly advanced design. Your desire to take Wofati to the next level is intriguing. I hope you'll share your results.
“Uncertainty is an uncomfortable position. But certainty is an absurd one.”
You have a number of ideas that could make a wofati more durable or efficient, at significantly higher cost than the original concept (which counts on a lot of recycled or repurposed or site-derived material). There are also a lot of ideas that are additional to the basic wofati concept and could be equally applied to any building method.
I think concentrating on things you think would work better to achieve the original purpose would be a productive discussion. I do agree that the dry Montana climate where softwood posts can be buried without rotting quickly (even gravel-encased) is not applicable to large parts of the world, and makes the original construction method not universally feasible. I would concentrate on methods that could separate wood from moisture in damper climates without expensive or noxious or high-tech materials, for one thing.
Using wood-to-wood joints would definitely be more sustainable than metal pegs and connectors; that gets into timber-framing techniques which are wonderful but also require skill and training, while the metal pins are a fast and low-skill method, thus accessible to more people.
A tile roof surface (instead of a plastic layer) would work only if it had a porous layer on top of it to permit fast free drainage; otherwise water could back up and flow into tile joints. Large well-sorted gravel might work, or a second tile layer to keep a tiny air space above the first layer.
Moss (or sedum or other xeric vegetation for sunny locations) would be fine as long as the ground surface is low-slope enough to not risk erosion. For steeper areas, grass would be safer, and holding moisture into steeper-sloped areas should not be such an issue. If you want to collect water from a living roof, that is another issue which can be dealt with in creative ways worth discussing.
Compacting the soil under the umbrella would make it more dense and have more heat capacity, but also more conducting... perhaps compacting several feet around the walls and leaving the rest of the umbrella area uncompacted would give the best results? Adding earth tubes in loops or something to more effectively get heat to and from the umbrella area is another topic that could be worth discussing. We haven't really had a full test of the wofati concept for passive annual heat storage, to find out if summer heat really can be gotten into the umbrella mass. I have no doubt that once stored, it could reliably warm the space for some part of the winter.
Screaming fools! It's nothing more than a tiny ad:
"Permaculture Now! - Desert or Paradise?" movie by Sepp Holzer