Integrative Bio-Systems Design.

Nautilus Earthbuilding


The nautilus was designed by Flo Kroll, architect Helene .v.d.Merwe, and Helena Wagener during the preparation of the Sustainable Built Environment conference 2005.

Synergetic integration of Earthbuilding and Ecological Design

The Nautilus integrates various earthbuilding methods, including sandbag, cob, adobe, and straw bale. Biomimicry - the application of evolutionary design intelligence to human needs, suggests that natural patterns can be usefully applied to the design of buildings and settlements.

The Nautilus design uses a universal natural pattern, the spiral, as its aesthetic and functional point of reference. The spiral allows wind catchment and climate control, optimal orientation, passive solar gain in winter, economic rainwater harvesting, and ergonomic flow of everyday activities using a minimum of building material.

nautilus plan

An artistic rendition of the ground floor plan.

The Nautius also applies evolutionary design intelligence by the use of different surface areas on different sides of the building. Where a large surface area is desired - in this case to maximise northern solar mass exposure during winter, crenellation is used to increase surface area. Where energy exchange is less desirable, a minimal surface area is presented.

The building and its inhabitants are designed to form a coherent bio-system that is to be largely autonomous in terms of its use of energy, water, and biomass by integrating a variety of renewable energy sources, water catchment and filtration systems, and waterless ecological sanitation systems with the immediate environment - the Synergy Gardens.

Site Preparation and Launch

Site preparation and training was assisted by Pete Savage. The first walls were raised in June 2005 as part of the 2005 Sustainable Built Environment conference, with the help of architect Etienne Bruwer, strawbale-expert Pete Mackintosh, and lime-expert Jill Hogan.

Work has continued slowly since the initial workshop, progressing as our private funding allowed.


Without a formal background in engineering or construction science, some of our initial ideas and assumptions were naively starry-eyed.

A first try at an earthen roof failed - trusses were far too weak, the spacing too wide, and the light-clay and cob roofing far too heavy. As a result, a large section of the roof had to be re-done. Thicker roof trusses were set in cob, spaced much closer together, in accordance with calculations for strength.

Resilience to African Rainy Season

Due to the extremely slow process of building, the structure has now been exposed to 4 rainy seasons. Amazingly, there is very little apparent damage - with the exception of some of the arches, which have suffered some erosion. So far, cob has performed better than strawbale, adobe or sandbag in terms of ease of building and durability.

Lightweight Roof

20090322-012To maintain a minimal roof weight, yet sculpt a monolithic roof structure that follows the quirky curves of the nautilus’ spiral, we had to develop innovative new applications of different technologies.

Currently, we are starting the final run of plastering the new roof, which consists of bundles of reeds tied transversely across the roof trusses. These bundles are being plastered with a light-weight mix of papercrete - paper pulp, cement, and builders’ lime.

So far the test sections plastered in this way show very little cracking, and almost no erosion. They are light, and due to their porous structure, seem to insulate fairly well. We are confident that we are onto something very useful here, judging by the ease with which it responds to the quirky geometry of the nautilus.

Moving forward

We are now raising the necessary funding to complete plastering the rest of the roof area. Once we have completed a water-tight roof, all the other sections of walling will be out of the rain. Then, we can begin work on the interior, and on fittings. We hope to be able to inhabit the Nautilus within the next few months.

The roof is almost done…just in time!

Only a small section of the northern roof remains to be finished. The papercrete is performing very well. Some cracks have appeared, but we will fill these with window-putty, to allow them to expand and flex to accommodate the structure’s movements (thermal, humidity-induced). Close inspection has revealed damage to some of the strawbales in the southern wall. These will need to be replaced carefully, after the trusses are buttressed externally with cob arches.

Once again, the slow pace and emergent nature of the nautilus require incremental adjustments and modifications - on the fly!

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