[Strawbale] Cob Core Building proposal for Haiti

Caroline Meyer White hojtpaastraa at gmail...
Mon Mar 15 10:58:35 CET 2010

Hi Max,

If you have any documentation for the earthquake resistance to +9 on the
richter scale, I would be VERY interested to see it.


2010/3/15 Max Vittrup Jensen <max at permalot...>

>  Dear all,
> I'm close to done with the cob-core building proposal; my recommendation
> over SB, earthships, superadobe, bamboo huts etc. Please feel free to use it
> in anyway you may see fit if you're involved in relief work. (And I'd
> appreciate suggestions for improvements.)  I'll gradually fill in the blanks
> in the budget, and adjust if I've made any mistakes. Apart from that I'm off
> Haiti, devoting my spring to more local issues...such as finalizing our
> straw bale house and co-facilitating our internships.
> This is the first introduction. Please enjoy the full text with numerous
> links and illustrations on: http://nbnetwork.org/nb/haiticob
> Max Vittrup Jensen
> Director, Events and Marketing
> Natural Building Network
>    Important Disclaimer:
> NBN is only a network. Our role in this plan has been to connect the people
> with expertise in Natural Building, as well as advice an effective approach
> in view of the local available local material, economy, climate challenges
> and historical/cultural preferences of Haitians. These parameters has
> eliminated a series of more exotic building designs and techniques.
> NBN does not have the funding and resources to proceed with implementation
> of the plan, this is up to whoever wants to make use of it. The plan is
> written in a pro-active tone by Max Vittrup Jensen, (NBN board member),
> enabling it to be downloaded and used for submission. Please do not
> interpret this as if the project is already being implemented. It is
> important to emphasize that this is a plan open for everyone to adapt and
> use, just make sure you’ll contact the relevant experts/sub contractors if
> you plan to include them in your application.
>     ———–00O00————
> The aim of this project is to construct 4000 simple 4×5 meter earthquake
> proven (9+) core-shelters out of bamboo re-enforced cob, which residents
> easily can expand into family houses in the future. Our emphasis is to work
> with future residents in design of their community and structures: The
> process is based on training Haitian low-income owner-builder teams, who’ll
> afterward be in charge of small mobile commercial equipment, establishing
> local skills and enterprises. We outline how three sustainable
> micro-businesses will be established as part of the process.
> A central element in organizing the community is a planning process with
> future inhabitants, facilitated by experienced experts in permaculture and
> urban design. This process will result in sustainable neighborhood groups,
> which commits to jointly build a cluster of dwellings; approximately 10-20
> families per group. Key features of the project will be enhancement of
> community facilities, rainwater catchments, local waste-water treatment, and
> garden allotments.
> We will then construct 10′ x 16′ Core homes that are earthquake proven
> (9+). They will be built out of bamboo re-enforced cob (a mixture of earth
> and straw), which residents easily can expand into family houses in the
> future. Building together with both Haitians and international volunteers,
> after an extensive training and guidance the foreign builders will gradually
> withdraw to an advisory role, while repeating the process for other groups.
> Our aim is to build structures which residents easily can expand into family
> houses in the future. The process is based on importing simple mobile earth
> and straw mixing machines from Czech Republic, in order to expedite the
> building process.
> Image of cob shed in Oregon; thicker walls and different roof. This is
> without bamboo re-enforcement. Click here for quake test of such structure
>    Addressing the Challenge: Cob Core Housing
> Requirements
> Thanks to extensive networking contacts and reports from Haiti relief
> workers,  along with the recommendation from the Haiti UN housing Cluster,
> it has been concluded that addressing the housing shortage in Haiti for the
> short-term means having a solution that meets the following key
> requirements:
>     * Feeling of safety and comfort for inhabitants relative to seismic
> activity
>     * Hurricane-ready
>     * Heat and flood management
>     * Durability
>     * High effectiveness in construction; utilize simple tools and trained
> teams of assembly technicians working with untrained local labor
>     * Scalable production
>     * Low cost
>     * Low environmental impact
> The cob-core units presents a solution to all of those challenges, while
> predominantly utilizing local materials, and allowing for future expansion
> of the units.
> The use of Earthen construction allows for inclusion of minimum trained
> labor of all genders and ages. It serve to regulate the interior heat, and
> is freely available.  Apparently Haitians are not very likely to adapt to
> non-traditional shapes of housing, and hence our model is proposed as a
> simple rectangle with a sloped roof: In due time other rooms can be attached
> and the roof become a saddle roof. Earthen construction is usual in Haiti as
> in the wattle and daub technique; Our technique is somewhat the same,
> however further improved for seismic activity and floods: We make a
> foundation out of old chunks of concrete, secure plastic ties under the
> concrete which gets embedded in the walls and are used to tie the
> light-weight bamboo roof construction to the foundation. The four wall
> sections are made of split bamboo woven into a 6 inch grid, and with
> diagonal split bamboo included, in effect making a hexagon pattern in the
> grid. This techniques was developed by J. Becker during relief work in Banda
> Aceh, Indonesia.
> The cob machines are specially designed to fast and effectively mix earth
> with long fibers, while remaining of a quite simple and sturdy mobile
> design. The cob mixture is applied from both sides in about 4 inch
> thickness, while making sure that the long fibres (straw or local grasses)
> are inserted through the holes of the bamboo grid into the mixture on the
> other side. This way the cob core in effect becomes a monolithic structure,
> which (once dry) is virtually non-destructible. As bamboo is a grass, and
> the split pieces treated by boiling and kiln dried, they are of no interest
> to termites.
> Despite the high humidity the cob walls will dry relatively fast due to
> breeze and the high average temperatures. Both the external sides of the
> structure will get a lime plaster, which prevents damage from driving rain.
> The resulting structure is more sturdy than the phase 2 structures proposed
> by the Haiti UN housing Cluster, hence resisting hurricanes better,  yet
> there is very limited possibility of the roof or walls doing any harm to the
> inhabitants, should an extreme magnitude earthquake manage to damage the
> walls or roof.
> The light weight concrete roof tiles represent a much lower degree of
> embodied energy and cost, than the typical corrugated metal roofs, it does
> not transfer heat to the interior in same way as metal, and it dulls the
> sound of the torrential rainfall, while allowing for suitable clean water to
> be captured and reused.
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