Design Overview


CyberHobbit Home Design
To get an overview of the design, we begin with the general plan for the house, including: The basic scheme is an earthsheltered tied-vault whose endwalls and main interior walls are rammed earth for its thermal, economic and solid strength. The shell of the vault is ferrocement on the concave/tension side and rammed earth above. Over that is the insulation umbrella, extending 20feet beyond the living space in all directions and sheltering the heatsinks that eliminate the need for hvac by harvesting the solar warmth in the summer months when its plentiful, storing it in the thermal mass to be drawn on when the winter months arrive.

The curve of the vault is to be a catenary, spreading 110´ end-to-end and rising 18´ at the center... it turns out that this is less than an inch different from 1/5th of a circle 93´ in radius, which is the compression part of the circle...

the length of the vault is 65´, reaching between the 2´ thick endwalls of rammed earth... each of the entrances is an airlock and the interior is lit by the 5 sunpipes rising through the vault...


Front Elevation
Facing East.
Back Elevation
Facing West.


The construction of the vault is planned to begin with stretching welded wire fencing between the endwalls´ bondbeams and wiretying expanded metal mesh to the underside... at the springline, the wwm is tied to the mesh embedded in the slab, running up through the footer-wedge which serves as a brace-containment for the bottom of the eventual rammed earth shell... after the first mortar is placed in the initial layers of mesh, it serves as a form, over which we can alternately pour layers of mortar and embed mesh to a thickness of about 2"... air-entrainer, superplasticizer and polypropylene fibers in a low-water mortar are intended...

This ferrocement shell should support the process, beginning at each springline, of building a 10" high rammed earth waffle-like structure, which in turn serves as the formwork for ramming the spaces in the waffle pattern to complete the rammed earth shell..

Over this double shell is placed layers of polyethylene foam sheeting (packaging material from a listing in the Hamilton county waste exchange) to a depth of 5"-6" and extending beyond the footprint of the house to the requisite 20´ from the living space in all directions... on the lotplan there´s a dashed curve for the edge of that insulation umbrella... the polyethylene can be laid shingle-like to shed water into the irrigation trenches... over the iu is placed 9" of topsoil...

on the lotplan is also shown the swaths of trenching where the soil for ramming is gotten and subsequently replaced with gravel to form the irrigation system and rainwater catchment to serve the orchard as well as drain the water away from the house... the soil is mixed 50-50 with sand before cement, and very little water, are added, tilled and ready for ramming...

The soil data is discussed separately in the section on soil science research...

The max 60 minute rainfall in Ohio was 6.25" which would have dropped about 3600 cf of water on the house but the trench around the house is 5´ wide and 3´ deep at least and almost 400´ long (with again as much watershed space on either side of the driveway), so the circum-house trench would accomodate most of that water, allowing 50% of the volume for the gravel, and since only the driveway sheds into the trenches alongside it (the lot slightly slopes to each side), that should leave ample space for the water to move around the orchard trenches... in addition, you have the factor that water would move more slowly down the grassy slopes of the green roof than off the more pavement-like surface of a traditional roof, giving the trenches time to carry the flow away better than simply filling the circum-house trench...



The self-loads, the soil and snow load generate about 4000lbs of thrust per linear foot at the springline, which is resisted by the tie to the slab, the footer-wedge and the weight of the large wedge heatsinks at the springlines (see the floorplan)... the live load will be a couple people and our loader which weighs a bit under a ton carrying a typical load...

The interior living space is divided into three east-to-west modules whose only enclosed areas (7´ room ceilings there) are the baths, the laundry, pantry and offices... end-to-end open airflow (except in the garage/sunpit module).. the modules are defined by floor-to-ceiling 2´ thick rammed earth walls running east-to-west with 2 buttresses on each side roughly equidistant apart...

(one inconsistency in the drawings is the location of the generator´s space, which is on the south side of the driveway in the elevation drawings but should be on the north like the lotplan so that its doors open south onto the driveway just at the garage door)...

See also the thermal performance spreadsheet to show month-by-month performance and the logic of passive annual heat storage to justify the omission of the hvac system...

plus other drawings for the movement of the water table, the greywater systems and whatever else we can supply you.. hopefully I've done them all by now, from economic stuff to workload... let me know if anything above or in the drawings is unclear...