Simple Solar Homesteading

Off-Grid Cabin and Tiny House Designs and Supplies
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Joshua Dolan Micro-Max Tire wall House

Posted on June 7, 2014 at 8:05 PM

The Micro-max tries to take the idea of a single occupant/couple living unit to its maximum by providing modern living conveniences with minimal impact using highly sustainable construction and a tiny footprint.

The basic construction uses dozens of old worn out tires, packed with dirt, until they are a solid “brick” that are stacked to form the exterior structural walls of the unit. Nails are then hammered in to form a web for concrete to be troweled onto and smoothed for form the basic interior wall surface. Around the outside of the tires a ~4 foot deep dirt berm is filled in which is then wrapped in segments of insulating foam (to increase heat retention) and then the berm is extended out to the natural level of the ground around the home.

A center structural beam runs across the width of the house which supports the roof trusses (in this design wooden pre-fab i-beams) over which a standard decking and metal roof is applied. At the back of the sloped roof a gutter channels all of the collected rainwater into one or more cisterns that sit behind the building and within the berm. Within the space standard 2x4 framing (or 2x3 to save precious inches) with drywall forms the interior walls separating the living area, bathroom, and bedroom. All of the internal fixtures and layout can be adjusted by the owner to fit their needs but this design uses a tiny ~20 square foot bathroom utilizing concepts from RVs and a friends description of bathrooms seen in the Philippines where the toilet is part of the shower unit (to maximize hygienic use by it constantly getting washed) to minimize space requirements.

At the back of the living room and bedroom two 4 inch ABS or PVC ducts run out through the tire wall and through the berm until they are exposed to the air. The open ends outside are covered with a mesh grille and screen to keep critters out but allow air into the home. To the front of the unit over the windows two vents are positioned behind the solar PV cells that are opened or closed as needed to allow air to flow through the home. Convection of warm / hot air during the summer draws cool air through the air ducts, through the berm, further cooling it by transferring heat into the berm, and thus cooling the home. The living space also includes a small wood burning stove near the front door for added warmth if desired during the winter months. (However, Earthships have proven over 40 years the ability to maintain a 60 - 70 def F living space with no additional heating except for the sun and stored thermal energy.)

The front of the building is comprised of several large panel windows (in my design they are meant to be recovered from a commercial property I work at that is scheduled for major renovations, and the height of the home is scaled appropriately). These windows serve to allow ample light in for heating the home during winter. In this design the traditionally included grey water treatment system of a indoor grow bed has been moved out front into a loop greenhouse.

Above the windows sit a row of solar panels for generating electricity which is transferred to a bank of batteries and the 120v inverter placed at the back of the home in the galley kitchen. 12v is used directly in the interior lighting of the home provided by recessed LED lamps to efficiently use electricity. 120v runs to several outlets located in the kitchen, bathroom, and bedroom for powering standard devices.

The collected rainwater in the cisterns is pumped on demand as in an RV and filtered through several filters before splitting off to tankless heater for showering and sinks. Flexible hosing is run throughout to carry water where needed. Drains from the shower and sink run under the floor slab to the grow bed where the water is filtered by rocks, sand, and plants before either settling at the bottom low end “grey-water” pit of the grow bed or over flowing to a junction that feeds into the black-water waste to a conventional septic tank. The grey-water has an on demand loop that feeds back to the toilet for flushing, which connects to the dedicated black-water line out to the septic. The septic tank drains to a standard drainage field.


Categories: 2014 Contest Submissions

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1 Comment

Reply Knot-Kupid
8:39 PM on July 17, 2014 
Looks like you opted for the Earthship Biotecture approach here. Personally, I've used rammed earth for a similar approach in the past and as long as you provide a good solution for water proofing your external berm walls your interior stays liveable or you only build it in dry desert climes. This bermed design also works well in conditioning the living space between daily and seasonal temperature extremes. Sorry, but I just noticed you sort of skipped the water penetration aspect in your text note and wondered about it.


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